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Scholl A, Ndoja I, Dhakal N, Morante D, Ivan A, Newman D, Mossington T, Clemans C, Surapaneni S, Powers M, Jiang L. The Osiris family genes function as novel regulators of the tube maturation process in the Drosophila trachea. PLoS Genet 2023; 19:e1010571. [PMID: 36689473 PMCID: PMC9870157 DOI: 10.1371/journal.pgen.1010571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 12/14/2022] [Indexed: 01/24/2023] Open
Abstract
Drosophila trachea is a premier model to study tube morphogenesis. After the formation of continuous tubes, tube maturation follows. Tracheal tube maturation starts with an apical secretion pulse that deposits extracellular matrix components to form a chitin-based apical luminal matrix (aECM). This aECM is then cleared and followed by the maturation of taenidial folds. Finally, air fills the tubes. Meanwhile, the cellular junctions are maintained to ensure tube integrity. Previous research has identified several key components (ER, Golgi, several endosomes) of protein trafficking pathways that regulate the secretion and clearance of aECM, and the maintenance of cellular junctions. The Osiris (Osi) gene family is located at the Triplo-lethal (Tpl) locus on chromosome 3R 83D4-E3 and exhibits dosage sensitivity. Here, we show that three Osi genes (Osi9, Osi15, Osi19), function redundantly to regulate adherens junction (AJ) maintenance, luminal clearance, taenidial fold formation, tube morphology, and air filling during tube maturation. The localization of Osi proteins in endosomes (Rab7-containing late endosomes, Rab11-containing recycling endosomes, Lamp-containing lysosomes) and the reduction of these endosomes in Osi mutants suggest the possible role of Osi genes in tube maturation through endosome-mediated trafficking. We analyzed tube maturation in zygotic rab11 and rab7 mutants, respectively, to determine whether endosome-mediated trafficking is required. Interestingly, similar tube maturation defects were observed in rab11 but not in rab7 mutants, suggesting the involvement of Rab11-mediated trafficking, but not Rab7-mediated trafficking, in this process. To investigate whether Osi genes regulate tube maturation primarily through the maintenance of Rab11-containing endosomes, we overexpressed rab11 in Osi mutant trachea. Surprisingly, no obvious rescue was observed. Thus, increasing endosome numbers is not sufficient to rescue tube maturation defects in Osi mutants. These results suggest that Osi genes regulate other aspects of endosome-mediated trafficking, or regulate an unknown mechanism that converges or acts in parallel with Rab11-mediated trafficking during tube maturation.
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Affiliation(s)
- Aaron Scholl
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Istri Ndoja
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Niraj Dhakal
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Doria Morante
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Abigail Ivan
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Darren Newman
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Thomas Mossington
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Christian Clemans
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Sruthi Surapaneni
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Michael Powers
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
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2
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Scholl A, Chen J, Cardona D. Synovial Sarcoma Isn’t Supposed to To This! Am J Clin Pathol 2022. [DOI: 10.1093/ajcp/aqac126.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Abstract
Introduction/Objective
NA.
Methods/Case Report
A 35 year old male construction worker with no significant medical history presented with left posterior knee pain, weakness and numbness. Onset of symptoms coincided with an acute gout attack three months prior. Imaging revealed a 6.3 x 6.4 x 6.2 cm intraarticular, multicystic mass arising from the anterior cruciate ligament and extending posteriorly to displace the popliteal artery and vein. It was heterogenous, partially enhancing and aggressive appearing with associated bone erosion of the femoral condyle. Needle core biopsy showed a biphasic synovial sarcoma (SS), confirmed by SS18 gene rearrangement by fluorescence in situ hybridization. The patient underwent an above the knee amputation. Histologic examination of the resected tumor revealed a heterogenous histology. There were areas characteristic of a biphasic SS, hyperchromatic spindle cells, intermixed epithelial clusters and calcifications, and solid areas of round cells with necrosis and staghorn vessels, consistent with poorly differentiated SS. Additionally, a third histologic appearance with large pleomorphic tumor cells, markedly atypical mitotic figures and what appears to be matrix production was noted. These latter findings are not well described in SS but is suggestive of dedifferentiation. Next generation sequencing was performed, focused on the dedifferentiated appearing area, which confirmed the presence of SS18-SSX1 fusion. Additional findings included PDGFRA amplification and p53 mutation. We present this interesting case in order to demonstrate a previously undescribed variant of synovial sarcoma which could be a potential pitfall, especially had this been the area initially sampled in the biopsy.
Results (if a Case Study enter NA)
NA.
Conclusion
NA.
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Affiliation(s)
- A Scholl
- Pathology, Duke , Durham, North Carolina , United States
| | - J Chen
- Pathology, Duke , Durham, North Carolina , United States
| | - D Cardona
- Pathology, Duke , Durham, North Carolina , United States
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3
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Scholl A, De S. Epigenetic Regulation by Polycomb Complexes from Drosophila to Human and Its Relation to Communicable Disease Pathogenesis. Int J Mol Sci 2022; 23:ijms232012285. [PMID: 36293135 PMCID: PMC9603650 DOI: 10.3390/ijms232012285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 10/04/2022] [Accepted: 10/10/2022] [Indexed: 12/05/2022] Open
Abstract
Although all cells in the human body are made of the same DNA, these cells undergo differentiation and behave differently during development, through integration of external and internal stimuli via 'specific mechanisms.' Epigenetics is one such mechanism that comprises DNA/RNA, histone modifications, and non-coding RNAs that regulate transcription without changing the genetic code. The discovery of the first Polycomb mutant phenotype in Drosophila started the study of epigenetics more than 80 years ago. Since then, a considerable number of Polycomb Group (PcG) genes in Drosophila have been discovered to be preserved in mammals, including humans. PcG proteins exert their influence through gene repression by acting in complexes, modifying histones, and compacting the chromatin within the nucleus. In this article, we discuss how our knowledge of the PcG repression mechanism in Drosophila translates to human communicable disease research.
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4
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Abstract
COPD, a chronic obstructive pulmonary disease, is one of the leading causes of death worldwide. Clinical studies and research in rodent models demonstrated that failure of repair mechanisms to cope with increased ROS and inflammation in the lung leads to COPD. Despite this progress, the molecular mechanisms underlying the development of COPD remain poorly understood, resulting in a lack of effective treatments. Thus, an informative, simple model is highly valued and desired. Recently, the cigarette smoke-induced Drosophila COPD model showed a complex set of pathological phenotypes that resemble those seen in human COPD patients. The Drosophila trachea has been used as a premier model to reveal the mechanisms of tube morphogenesis. The association of these mechanisms to structural changes in COPD can be analyzed by using Drosophila trachea. Additionally, the timeline of structural damage, ROS, and inflammation can be studied in live organisms using fluorescently-tagged proteins. The related function of human COPD genes identified by GWAS can be screened using respective fly homologs. Finally, the Drosophila trachea can be used as a high-throughput drug screening platform to identify novel treatments for COPD. Therefore, Drosophila trachea is an excellent model that is complementary to rodent COPD models.
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5
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Díaz J, Gargiani P, Quirós C, Redondo C, Morales R, Álvarez-Prado LM, Martín JI, Scholl A, Ferrer S, Vélez M, Valvidares SM. Chiral asymmetry detected in a 2D array of permalloy square nanomagnets using circularly polarized x-ray resonant magnetic scattering. Nanotechnology 2020; 31:025702. [PMID: 31546237 DOI: 10.1088/1361-6528/ab46d7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The sensitivity of circularly polarized x-ray resonant magnetic scattering (CXRMS) to chiral asymmetry has been demonstrated. The study was performed on a 2D array of Permalloy (Py) square nanomagnets of 700 nm lateral size arranged in a chess pattern, in a square lattice of 1000 nm lattice parameter. Previous x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) images on this sample showed the formation of vortices at remanence and a preference in their chiral state. The magnetic hysteresis loops of the array along the diagonal axis of the squares indicate a non-negligible and anisotropic interaction between vortices. The intensity of the magnetic scattering using circularly polarized light along one of the diagonal axes of the square magnets becomes asymmetric in intensity in the direction transversal to the incident plane at fields where the vortex states are formed. The asymmetry sign is inverted when the direction of the applied magnetic field is inverted. The result is the expected in the presence of an unbalanced chiral distribution. The effect is observed by CXRMS due to the interference between the charge scattering and the magnetic scattering.
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Affiliation(s)
- J Díaz
- Depto. Física, Universidad de Oviedo, E-33007 Oviedo, Spain. CINN (CSIC-Univ. de Oviedo), E-33940 El Entrego, Spain
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Chen XM, Farmer B, Woods JS, Dhuey S, Hu W, Mazzoli C, Wilkins SB, Chopdekar RV, Scholl A, Robinson IK, De Long LE, Roy S, Hastings JT. Spontaneous Magnetic Superdomain Wall Fluctuations in an Artificial Antiferromagnet. Phys Rev Lett 2019; 123:197202. [PMID: 31765174 DOI: 10.1103/physrevlett.123.197202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Collective dynamics often play an important role in determining the stability of ground states for both naturally occurring materials and metamaterials. We studied the temperature dependent dynamics of antiferromagnetically ordered superdomains in a square artificial spin lattice using soft x-ray photon correlation spectroscopy. We observed an exponential slowing down of superdomain wall motion below the antiferromagnetic onset temperature, similar to the behavior of typical bulk antiferromagnets. Using a continuous time random walk model we show that these superdomain walls undergo low-temperature ballistic and high-temperature diffusive motions.
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Affiliation(s)
- X M Chen
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
| | - B Farmer
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - J S Woods
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - S Dhuey
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - W Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - R V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - I K Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- London Centre for Nanotechnology, University College, Gower Street, London WC1E 6BT, United Kingdom
| | - L E De Long
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - S Roy
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J T Hastings
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
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7
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Scholl A, O'Brien MJ, Chandran RR, Jiang L. The novel gene
apnoia
regulates
Drosophila
tracheal tube size. Dev Dyn 2019; 248:477-487. [DOI: 10.1002/dvdy.29] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 03/06/2019] [Accepted: 03/09/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Aaron Scholl
- Department of Biological SciencesOakland University Rochester Michigan
| | | | | | - Lan Jiang
- Department of Biological SciencesOakland University Rochester Michigan
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8
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Abstract
The Drosophila embryonic tracheal network is an excellent model to study tube size. The chitin-based apical luminal matrix and cell polarity are well known to regulate tube size in Drosophila trachea. Defects in luminal matrix and cell polarity lead to tube overexpansion. Here, we address the novel function of the rebuff (reb) gene, which encodes an evolutionarily conserved Smad-like protein. In reb mutants, tracheal tubes are moderately over-elongated. Despite the establishment of normal cell polarity, we observed significantly reduced apical luminal matrix in reb mutants. Among various luminal components, luminal Obstructor-A (ObstA) is drastically reduced. Interestingly, ObstA is localized in vesicle-like structures that are apically concentrated in reb mutants. To investigate the possibility that reb is involved in the endocytosis of ObstA, we analyzed the co-localization of ObstA and endocytic markers in reb mutants. We observed that ObstA is localized in late endosomes and recycling endosomes. This suggests that in reb mutant trachea, endocytosed ObstA is degraded or recycled back to the apical region. However, ObstA vesicles are retained in the apical region and are failed to be secreted to the lumen. Taken together, these results suggest one function of reb is regulating the endocytosis of luminal matrix components. Summary: Novel function of Smad-like protein Rebuff in regulating tube size of Drosophila trachea through endocytosis of luminal matrix components.
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Affiliation(s)
- Rachana R Chandran
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Aaron Scholl
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Yuyang Yang
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
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9
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Scholl A, Marcus MA, Doran A, Nasiatka JR, Young AT, MacDowell AA, Streubel R, Kent N, Feng J, Wan W, Padmore HA. Hartmann characterization of the PEEM-3 aberration-corrected X-ray photoemission electron microscope. Ultramicroscopy 2018; 188:77-84. [PMID: 29554489 DOI: 10.1016/j.ultramic.2018.03.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 11/24/2022]
Abstract
Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when using x-rays. We demonstrate this improved performance by imaging test patterns employing element and magnetic contrast.
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Affiliation(s)
- A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA.
| | - M A Marcus
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - A Doran
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - J R Nasiatka
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - A T Young
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - A A MacDowell
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - R Streubel
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - N Kent
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA; Department of Physics, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - J Feng
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - W Wan
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
| | - H A Padmore
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA
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10
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Scholl A, Yang Y, McBride P, Irwin K, Jiang L. Tracheal expression of Osiris gene family in Drosophila. Gene Expr Patterns 2018; 28:87-94. [PMID: 29548969 DOI: 10.1016/j.gep.2018.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/25/2018] [Accepted: 03/02/2018] [Indexed: 11/25/2022]
Abstract
The Drosophila trachea is a premier genetic system to investigate the fundamental mechanisms of tubular organ formation. Development of the trachea consists of the well understood early branch specification and migration processes, and the less clear later branch maturation process including the apical membrane expansion, cytoskeleton rearrangement, luminal matrix clearance, and air-filling. We identified seven members of the Osiris (Osi) gene family with obvious tracheal expression in Drosophila. In addition, HA-tagged Osi proteins are highly concentrated in vesicle-like structures at and near the apical membrane. Osi proteins are predicted to contain endocytic signals and transmembrane domains. The localization of Osi proteins is consistent with these predictions. Interestingly, the Drosophila tracheal tube maturation process also occurs at the apical membrane. Taken together, the localization of Osi proteins suggest that these proteins are likely involved in tube maturation through vesicular trafficking or interacting with other apical membrane proteins.
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Affiliation(s)
- Aaron Scholl
- Department of Biological Sciences, Oakland University, USA
| | - Yuyang Yang
- Department of Biological Sciences, Oakland University, USA
| | | | - Kelly Irwin
- Department of Biological Sciences, Oakland University, USA
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, USA.
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11
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Damodaran AR, Clarkson JD, Hong Z, Liu H, Yadav AK, Nelson CT, Hsu SL, McCarter MR, Park KD, Kravtsov V, Farhan A, Dong Y, Cai Z, Zhou H, Aguado-Puente P, García-Fernández P, Íñiguez J, Junquera J, Scholl A, Raschke MB, Chen LQ, Fong DD, Ramesh R, Martin LW. Phase coexistence and electric-field control of toroidal order in oxide superlattices. Nat Mater 2017; 16:1003-1009. [PMID: 28783161 DOI: 10.1038/nmat4951] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 06/28/2017] [Indexed: 06/07/2023]
Abstract
Systems that exhibit phase competition, order parameter coexistence, and emergent order parameter topologies constitute a major part of modern condensed-matter physics. Here, by applying a range of characterization techniques, and simulations, we observe that in PbTiO3/SrTiO3 superlattices all of these effects can be found. By exploring superlattice period-, temperature- and field-dependent evolution of these structures, we observe several new features. First, it is possible to engineer phase coexistence mediated by a first-order phase transition between an emergent, low-temperature vortex phase with electric toroidal order and a high-temperature ferroelectric a1/a2 phase. At room temperature, the coexisting vortex and ferroelectric phases form a mesoscale, fibre-textured hierarchical superstructure. The vortex phase possesses an axial polarization, set by the net polarization of the surrounding ferroelectric domains, such that it possesses a multi-order-parameter state and belongs to a class of gyrotropic electrotoroidal compounds. Finally, application of electric fields to this mixed-phase system permits interconversion between the vortex and the ferroelectric phases concomitant with order-of-magnitude changes in piezoelectric and nonlinear optical responses. Our findings suggest new cross-coupled functionalities.
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Affiliation(s)
- A R Damodaran
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J D Clarkson
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Z Hong
- Department of Materials Science and Engineering, Pennsylvania State University, State College, Pennsylvania 16802, USA
| | - H Liu
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - A K Yadav
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- School of Electrical Engineering and Computer Science, UC Berkeley, Berkeley, California 94720, USA
| | - C T Nelson
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S-L Hsu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - M R McCarter
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA
| | - K-D Park
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA
| | - V Kravtsov
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA
| | - A Farhan
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Y Dong
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Z Cai
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - H Zhou
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - P Aguado-Puente
- Centro de Física de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain
- Donostia International Physics Center, 20018 San Sebastián, Spain
| | - P García-Fernández
- Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, avenida de los Castros s/n, 39005 Santander, Spain
| | - J Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxembourg
| | - J Junquera
- Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, avenida de los Castros s/n, 39005 Santander, Spain
| | - A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - M B Raschke
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA
| | - L-Q Chen
- Department of Materials Science and Engineering, Pennsylvania State University, State College, Pennsylvania 16802, USA
| | - D D Fong
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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12
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Gray AX, Jeong J, Aetukuri NP, Granitzka P, Chen Z, Kukreja R, Higley D, Chase T, Reid AH, Ohldag H, Marcus MA, Scholl A, Young AT, Doran A, Jenkins CA, Shafer P, Arenholz E, Samant MG, Parkin SSP, Dürr HA. Correlation-Driven Insulator-Metal Transition in Near-Ideal Vanadium Dioxide Films. Phys Rev Lett 2016; 116:116403. [PMID: 27035314 DOI: 10.1103/physrevlett.116.116403] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 06/05/2023]
Abstract
We use polarization- and temperature-dependent x-ray absorption spectroscopy, in combination with photoelectron microscopy, x-ray diffraction, and electronic transport measurements, to study the driving force behind the insulator-metal transition in VO_{2}. We show that both the collapse of the insulating gap and the concomitant change in crystal symmetry in homogeneously strained single-crystalline VO_{2} films are preceded by the purely electronic softening of Coulomb correlations within V-V singlet dimers. This process starts 7 K (±0.3 K) below the transition temperature, as conventionally defined by electronic transport and x-ray diffraction measurements, and sets the energy scale for driving the near-room-temperature insulator-metal transition in this technologically promising material.
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Affiliation(s)
- A X Gray
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19130, USA
| | - J Jeong
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - N P Aetukuri
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - P Granitzka
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Van der Waals-Zeeman Institute, University of Amsterdam, 1018XE Amsterdam, The Netherlands
| | - Z Chen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - R Kukreja
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - D Higley
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - T Chase
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - A H Reid
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - H Ohldag
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - M A Marcus
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A T Young
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A Doran
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - C A Jenkins
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - P Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - M G Samant
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - S S P Parkin
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - H A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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13
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Baldasseroni C, Bordel C, Antonakos C, Scholl A, Stone KH, Kortright JB, Hellman F. Temperature-driven growth of antiferromagnetic domains in thin-film FeRh. J Phys Condens Matter 2015; 27:256001. [PMID: 26043719 DOI: 10.1088/0953-8984/27/25/256001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The evolution of the antiferromagnetic phase across the temperature-driven ferromagnetic (FM) to antiferromagnetic (AF) phase transition in epitaxial FeRh thin films was studied by x-ray magnetic linear and circular dichroism (XMLD and XMCD) and photoemission electron microscopy. By comparing XMLD and XMCD images recorded at the same temperature, the AF phase was identified, its structure directly imaged, and its evolution studied across the transition. A quantitative analysis of the correlation length of the images shows differences between the characteristic length scale of the two phases with the AF phase having a finer feature size. The asymmetry of the transition from FM to AF upon cooling and AF-FM upon heating is evidenced: upon cooling the formation of AF phase is dominated by nucleation at defects, with little subsequent growth, resulting in a small and non-random final AF domain structure, while upon heating, heterogeneous nucleation at different sites followed by significant domain size growth of the FM phase is observed, resulting in a non-reproducible final FM large domain structure.
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Affiliation(s)
- C Baldasseroni
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
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14
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Hertlein MP, Scholl A, Cordones AA, Lee JH, Engelhorn K, Glover TE, Barbrel B, Sun C, Steier C, Portmann G, Robin DS. X-rays only when you want them: optimized pump-probe experiments using pseudo-single-bunch operation. J Synchrotron Radiat 2015; 22:729-35. [PMID: 25931090 PMCID: PMC4416684 DOI: 10.1107/s1600577515001770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 01/27/2015] [Indexed: 06/04/2023]
Abstract
Laser pump-X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser excitation pulse rates. Suppressing undesired X-ray pulses considerably reduces detector noise and improves signal to noise in time-resolved experiments. In addition, dose-induced sample damage is considerably reduced, easing experimental setup and allowing the investigation of less robust samples. Single-shot X-ray exposures of a streak camera detector using a conventional non-gated charge-coupled device (CCD) camera are also demonstrated.
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Affiliation(s)
- M. P. Hertlein
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - A. Scholl
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - A. A. Cordones
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - J. H. Lee
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - K. Engelhorn
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - T. E. Glover
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - B. Barbrel
- Department of Physics, University of California, 366 LeConte Hall, MC 7300, Berkeley, CA 94720, USA
| | - C. Sun
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - C. Steier
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - G. Portmann
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - D. S. Robin
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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15
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Hu XF, Wu J, Niu DX, Chen L, Morton SA, Scholl A, Huang ZC, Zhai Y, Zhang W, Will I, Xu YB, Zhang R, van der Laan G. Discontinuous properties of current-induced magnetic domain wall depinning. Sci Rep 2013; 3:3080. [PMID: 24170087 PMCID: PMC3812652 DOI: 10.1038/srep03080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 09/24/2013] [Indexed: 11/09/2022] Open
Abstract
The current-induced motion of magnetic domain walls (DWs) confined to nanostructures is of great interest for fundamental studies as well as for technological applications in spintronic devices. Here, we present magnetic images showing the depinning properties of pulse-current-driven domain walls in well-shaped Permalloy nanowires obtained using photoemission electron microscopy combined with x-ray magnetic circular dichroism. In the vicinity of the threshold current density (Jth = 4.2 × 1011 A.m−2) for the DW motion, discontinuous DW depinning and motion have been observed as a sequence of “Barkhausen jumps”. A one-dimensional analytical model with a piecewise parabolic pinning potential has been introduced to reproduce the DW hopping between two nearest neighbour sites, which reveals the dynamical nature of the current-driven DW motion in the depinning regime.
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Affiliation(s)
- X F Hu
- 1] Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD, UK [2] Nanjing-York International Center of Spintronics, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
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16
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Farhan A, Derlet PM, Kleibert A, Balan A, Chopdekar RV, Wyss M, Perron J, Scholl A, Nolting F, Heyderman LJ. Direct observation of thermal relaxation in artificial spin ice. Phys Rev Lett 2013; 111:057204. [PMID: 23952441 DOI: 10.1103/physrevlett.111.057204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/02/2013] [Indexed: 06/02/2023]
Abstract
We study the thermal relaxation of artificial spin ice with photoemission electron microscopy, and are able to directly observe how such a system finds its way from an energetically excited state to the ground state. On plotting vertex-type populations as a function of time, we can characterize the relaxation, which occurs in two stages, namely a string and a domain regime. Kinetic Monte Carlo simulations agree well with the temporal evolution of the magnetic state when including disorder, and the experimental results can be explained by considering the effective interaction energy associated with the separation of pairs of vertex excitations.
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Affiliation(s)
- A Farhan
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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17
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Polisetty S, Zhou J, Karthik J, Damodaran AR, Chen D, Scholl A, Martin LW, Holcomb M. X-ray linear dichroism dependence on ferroelectric polarization. J Phys Condens Matter 2012; 24:245902. [PMID: 22627181 DOI: 10.1088/0953-8984/24/24/245902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
X-ray absorption spectroscopy and photoemission electron microscopy are techniques commonly used to determine the magnetic properties of thin films, crystals, and heterostructures. Recently, these methods have been used in the study of magnetoelectrics and multiferroics. The analysis of such materials has been compromised by the presence of multiple order parameters and the lack of information on how to separate these coupled properties. In this work, we shed light on the manifestation of dichroism from ferroelectric polarization and atomic structure using photoemission electron microscopy and x-ray absorption spectroscopy. Linear dichroism arising from the ferroelectric order in the PbZr0:2Ti0:8O3 thin films was studied as a function of incident x-ray polarization and geometry to unambiguously determine the angular dependence of the ferroelectric contribution to the dichroism. These measurements allow us to examine the contribution of surface charges and ferroelectric polarization as potential mechanisms for linear dichroism. The x-ray linear dichroism from ferroelectric order revealed an angular dependence based on the angle between the ferroelectric polarization direction and the x-ray polarization axis, allowing a formula for linear dichroism in ferroelectric samples to be defined.
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Affiliation(s)
- S Polisetty
- Department of Physics, West Virginia University, Morgantown, WV 26506, USA.
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18
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Burkhardt MH, Hossain MA, Sarkar S, Chuang YD, Cruz Gonzalez AG, Doran A, Scholl A, Young AT, Tahir N, Choi YJ, Cheong SW, Dürr HA, Stöhr J. Imaging the first-order magnetic transition in La0.35Pr0.275Ca0.375MnO3. Phys Rev Lett 2012; 108:237202. [PMID: 23003984 DOI: 10.1103/physrevlett.108.237202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Indexed: 05/23/2023]
Abstract
The nature of the ferromagnetic, charge, orbital, and antiferromagnetic order in La0.35Pr0.275Ca0.375MnO3 on the nano- and microscale was investigated by photoemission electron microscopy (PEEM) and resonant elastic soft x-ray scattering (RSXS). The structure of the ferromagnetic domains around the Curie temperature T(C) indicates that they nucleate under a high degree of lattice strain, which is brought about by the charge, orbital, and antiferromagnetic order. The combined temperature-dependent PEEM and RSXS measurements suggest that the lattice distortions associated with charge and orbital order are glassy in nature and that phase separation is driven by the interplay between it and the more itinerant charge carriers associated with ferromagnetic metallic order, even well below T(C).
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Affiliation(s)
- Mark H Burkhardt
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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19
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Wu J, Carlton D, Oelker E, Park JS, Jin E, Arenholz E, Scholl A, Hwang C, Bokor J, Qiu ZQ. Switching a magnetic vortex by interlayer coupling in epitaxially grown Co/Cu/Py/Cu(001) trilayer disks. J Phys Condens Matter 2010; 22:342001. [PMID: 21403243 DOI: 10.1088/0953-8984/22/34/342001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Epitaxial Py/Cu/Co/Cu(001) trilayers were patterned into micron sized disks and imaged using element-specific photoemission electron microscopy. By varying the Cu spacer layer thickness, we study how the coupling between the two magnetic layers influences the formation of magnetic vortex states. We find that while the Py and Co disks form magnetic vortex domains when the interlayer coupling is ferromagnetic, the magnetic vortex domains of the Py and Co disks break into anti-parallel aligned multidomains when the interlayer coupling is antiferromagnetic. We explain this result in terms of magnetic flux closure between the Py and Co layers for the antiferromagnetic coupling case.
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Affiliation(s)
- J Wu
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
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20
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Kade A, Kummer K, Vyalikh DV, Danzenbächer S, Blüher A, Mertig M, Lanzara A, Scholl A, Doran A, Molodtsov SL. X-ray Damage in Protein−Metal Hybrid Structures: A Photoemission Electron Microscopy Study. J Phys Chem B 2010; 114:8284-9. [DOI: 10.1021/jp1040585] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Kade
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - K. Kummer
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - D. V. Vyalikh
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - S. Danzenbächer
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - A. Blüher
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - M. Mertig
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - A. Lanzara
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - A. Scholl
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - A. Doran
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - Serguei L. Molodtsov
- Institute of Solid State Physics, Technische Universität Dresden, 01062 Dresden, Germany, Institute of Air Handling and Refrigeration Dresden, 01309 Dresden, Germany, BioNanotechnology and Structure Formation Group, Max Bergmann Center of Biomaterials and Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany, Department of Physics, University of California, Berkeley, California 94720, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
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21
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Ceccone G, Leung BO, Perez-Roldan MJ, Valsesia A, Colpo P, Rossi F, Hitchcock AP, Scholl A. X-ray spectromicroscopy study of ubiquitin adsorption to plasma polymerized microstructures. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Wu J, Park JS, Kim W, Arenholz E, Liberati M, Scholl A, Wu YZ, Hwang C, Qiu ZQ. Direct measurement of rotatable and frozen CoO spins in exchange bias system of CoO/Fe/Ag(001). Phys Rev Lett 2010; 104:217204. [PMID: 20867133 DOI: 10.1103/physrevlett.104.217204] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Indexed: 05/29/2023]
Abstract
The exchange bias of epitaxially grown CoO/Fe/Ag(001) was investigated using x-ray magnetic circular dichroism and x-ray magnetic linear dichroism (XMLD) techniques. A direct XMLD measurement on the CoO layer during the Fe magnetization reversal shows that the CoO compensated spins are rotatable at thinner thickness and frozen at larger thickness. By a quantitative determination of the rotatable and frozen CoO spins as a function of the CoO film thickness, we find the remarkable result that the exchange bias is well established before frozen spins are detectable in the CoO film. We further show that the rotatable and frozen CoO spins are uniformly distributed in the CoO film.
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Affiliation(s)
- J Wu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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23
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Opachich YP, Comin A, Bartelt AF, Young AT, Scholl A, Feng J, Schmalhorst J, Shin HJ, Engelhorn K, Risbud SH, Reiss G, Padmore HA. Time-resolved demagnetization of Co2MnSi observed using x-ray magnetic circular dichroism and an ultrafast streak camera. J Phys Condens Matter 2010; 22:156003. [PMID: 21389561 DOI: 10.1088/0953-8984/22/15/156003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The demagnetization dynamics of the Heusler alloy Co(2)MnSi was studied using picosecond time-resolved x-ray magnetic circular dichroism. The sample was excited using femtosecond laser pulses. In contrast to the sub-picosecond demagnetization of the metal ferromagnet Ni, substantially slower demagnetization with a time constant of 3.5 ± 0.5 ps was measured. This could be explained by a spin-dependent band gap inhibiting the spin-flip scattering of hot electrons in Co(2)MnSi, which is predicted to be half-metallic. A universal demagnetization time constant was measured across a range of pump power levels.
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Affiliation(s)
- Y P Opachich
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA.
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24
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Goltz JP, Scholl A, Ritter CO, Klein D, Wittenberg G, Hahn D, Kickuth R. Minimal-invasive perkutane Implantation von Port-a-Cath-Systemen am Unterarm: klinische Erfahrungen bei 750 Patienten. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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Seo JW, Fullerton EE, Nolting F, Scholl A, Fompeyrine J, Locquet JP. Antiferromagnetic LaFeO(3) thin films and their effect on exchange bias. J Phys Condens Matter 2008; 20:264014. [PMID: 21694348 DOI: 10.1088/0953-8984/20/26/264014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Antiferromagnetic (AFM) orthoferrites are interesting model systems for exploring the correlation between their crystalline and AFM domains and the resulting exchange bias when coupled to a ferromagnetic layer. In particular, LaFeO(3) (LFO) has a Néel temperature, T(N) = 740 K, which is the highest in the orthoferrite family. The recent developments of synchrotron radiation-based photoelectron emission microscopy (PEEM) have provided the possibility of studying AFM domain structures as well as the magnetic coupling between the AFM and the adjacent ferromagnetic (FM) layer, domain by domain. Thin films of LFO have proved excellent candidates for such studies because their AFM domains are well defined and large enough to be readily imaged by PEEM. This paper reviews the growth, structural and magnetic properties of LFO thin films as well as exchange coupling to a FM layer. The strong correlation between structural and AFM domains in this material allows us to investigate the exchange coupling as a function of the domain configuration, which can be changed by using different substrate material and substrate orientation. A significant increase of the exchange bias field by a factor of about 10 was obtained when LFO was diluted with Ni atoms in the volume part. In this sample, the structural domain boundary became corrugated due to substitutional defects. Our results indicate that the details of the precise domain boundary configuration strongly affect the exchange coupling.
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Affiliation(s)
- J W Seo
- Department Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44-bus 2450, B-3001 Heverlee, Belgium
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26
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Dhein S, Duerrschmidt N, Scholl A, Boldt A, Schulte JS, Pfannmüller B, Rojas-Gomez D, Scheffler A, Haefliger JA, Doll N, Mohr FW. A new role for extracellular Ca2+ in gap-junction remodeling: studies in humans and rats. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:125-38. [PMID: 18278481 DOI: 10.1007/s00210-008-0265-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 01/20/2008] [Indexed: 10/22/2022]
Abstract
We wanted to elucidate whether extracellular calcium may regulate the expression of the cardiac gap-junction proteins connexin 40 and connexin43. In the free wall of the left atria of 126 cardiac surgery patients with either sinus rhythm (SR) or chronic atrial fibrillation (AF), we determined the expression of the cardiac gap-junction proteins Cx43 and Cx40 by Western blot and immunohistology. For deeper investigation, we incubated cultured neonatal rat cardiomyocytes at 2 or 4 mM Ca(++) for 24 h and determined intercellular coupling, Cx40, Cx43 protein and mRNA expression, protein trafficking and sensitivity to verapamil (10-100 nM), cyclosporin A (1 microM),and BMS605401 (100 nM), a specific inhibitor of Ca(2+)-sensing receptor (CaSR). We found in patients that both Cx are up-regulated in AF in the left atrium (by 100-200%). Interestingly, Cx40 was mainly up-regulated, if total serum calcium was >or=2.2 mM, while Cx43 was independent from extracellular [Ca(++)]. In cultured cells, 4 mM Ca(++)-exposure lead to up-regulation of Cx40, but not Cx43. We found enhanced Cx40 in the plasma membrane and reduced Cx40 in the Golgi apparatus. The membrane Cx40 up-regulation resulted in enhanced gap-junction intercellular coupling with a shift in the Boltzmann fit of voltage-dependent inactivation indicating a higher contribution of Cx40 as revealed by dual whole cell voltage clamp experiments. BMS605401 could prevent all Ca(2+)-induced changes. Moreover, cyclosporin A completely abolished the Ca(2+)-induced changes, while verapamil was ineffective. We conclude that extracellular calcium (24 h exposure) seems to up-regulate Cx40 but not Cx43.
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Affiliation(s)
- S Dhein
- Klinik für Herzchirurgie, Herzzentrum, Leipzig, Germany.
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27
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Litnovsky A, Rudakov D, De Temmerman G, Wienhold P, Philipps V, Samm U, McLean A, West W, Wong C, Brooks N, Watkins J, Wampler W, Stangeby P, Boedo J, Moyer R, Allen S, Fenstermacher M, Groth M, Lasnier C, Boivin R, Leonard A, Romanyuk A, Hirai T, Pintsuk G, Breuer U, Scholl A. First tests of diagnostic mirrors in a tokamak divertor: An overview of experiments in DIII-D. Fusion Engineering and Design 2008. [DOI: 10.1016/j.fusengdes.2007.06.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Choi J, Wu J, Won C, Wu YZ, Scholl A, Doran A, Owens T, Qiu ZQ. Magnetic bubble domain phase at the spin reorientation transition of ultrathin Fe/Ni/Cu(001) film. Phys Rev Lett 2007; 98:207205. [PMID: 17677736 DOI: 10.1103/physrevlett.98.207205] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 03/01/2007] [Indexed: 05/16/2023]
Abstract
Magnetic domain phases of ultrathin Fe/Ni/Cu(001) are studied using photoemission electron microscopy at the spin reorientation transition (SRT). We observe a new magnetic phase of bubble domains within a narrow SRT region after applying a nearly in-plane magnetic field pulse to the sample. By applying the magnetic field pulse along different directions, we find that the bubble domain phase exists only if the magnetic field direction is less than approximately 10 degrees relative to the sample surface. A temperature dependent measurement shows that the bubble domain phase becomes unstable above 370 K.
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Affiliation(s)
- J Choi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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Dhein S, Scholl A, Schulte J, Glawe I, Rojas-Gomez D, Salameh A, Doll N, Mohr FW. Betablockers can up-regulate cardiac intercellular communication channels: a new antiarrhythmic mechanism for an old therapy? Thorac Cardiovasc Surg 2007. [DOI: 10.1055/s-2007-967497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zhao T, Scholl A, Zavaliche F, Lee K, Barry M, Doran A, Cruz MP, Chu YH, Ederer C, Spaldin NA, Das RR, Kim DM, Baek SH, Eom CB, Ramesh R. Electrical control of antiferromagnetic domains in multiferroic BiFeO3 films at room temperature. Nat Mater 2006; 5:823-9. [PMID: 16951676 DOI: 10.1038/nmat1731] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 07/27/2006] [Indexed: 05/11/2023]
Abstract
Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. In this work, we demonstrate the first observation of electrical control of antiferromagnetic domain structure in a single-phase multiferroic material at room temperature. High-resolution images of both antiferromagnetic and ferroelectric domain structures of (001)-oriented multiferroic BiFeO3 films revealed a clear domain correlation, indicating a strong coupling between the two types of order. The ferroelectric structure was measured using piezo force microscopy, whereas X-ray photoemission electron microscopy as well as its temperature dependence was used to detect the antiferromagnetic configuration. Antiferromagnetic domain switching induced by ferroelectric polarization switching was observed, in agreement with theoretical predictions.
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Affiliation(s)
- T Zhao
- Department of Physics, University of California, Berkeley, California 94720, USA.
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Finazzi M, Brambilla A, Biagioni P, Graf J, Gweon GH, Scholl A, Lanzara A, Duò L. Interface coupling transition in a thin epitaxial antiferromagnetic film interacting with a ferromagnetic substrate. Phys Rev Lett 2006; 97:097202. [PMID: 17026395 DOI: 10.1103/physrevlett.97.097202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Indexed: 05/12/2023]
Abstract
We report experimental evidence for a transition in the interface coupling between an antiferromagnetic film and a ferromagnetic substrate. The transition is observed in a thin epitaxial NiO film grown on top of Fe(001) as the film thickness is increased. Photoemission electron microscopy excited with linearly polarized x rays shows that the NiO film is antiferromagnetic at room temperature with in-plane uniaxial magnetic anisotropy. The anisotropy axis is perpendicular to the Fe substrate magnetization when the NiO thickness is less than about 15 A, but rapidly becomes parallel to the Fe magnetization for a NiO coverage higher than 25 A.
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Affiliation(s)
- M Finazzi
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
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Boldt A, Scholl A, Garbade J, Resetar ME, Mohr FW, Dhein S, Gummert JF. ACE-inhibitor treatment attenuates atrial structural remodeling in patients with lone chronic atrial fibrillation. Thorac Cardiovasc Surg 2006. [DOI: 10.1055/s-2006-925754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Boldt A, Scholl A, Garbade J, Resetar ME, Mohr FW, Gummert JF, Dhein S. ACE-inhibitor treatment attenuates atrial structural remodeling in patients with lone chronic atrial fibrillation. Basic Res Cardiol 2005; 101:261-7. [PMID: 16382287 DOI: 10.1007/s00395-005-0571-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 10/20/2005] [Accepted: 10/21/2005] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Chronic atrial fibrillation (AF) is characterized by a remodeling process which involves the development of fibrosis. Since angiotensin II has been suspected to be involved in this process, the aim of our study was to investigate a possible influence of an ACE-I therapy in patients with chronic AF regarding the occurrence of left atrial structural remodeling. METHODS Atrial tissue samples were obtained from patients with lone chronic AF or sinus rhythm (SR). Collagen I, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) protein expression were measured by quantitative Western Blotting techniques and calculated as mean +/- SEM. Histological tissue samples were used for calculating microvessel density (microvessel/mm(2) +/- SEM). RESULTS In AF, the collagen amount was higher (1.78 +/- 0.21; p = 0.01) vs. SR (0.37 +/- 0.07) accompanied by declining microcapillary density (AF: 145 +/- 13 vs. SR: 202 +/- 9; p = 0.01). Additionally, a negative correlation (p = 0.01) between collagen content and microcapillary density was observed. To investigate the influence of an ACE-I therapy on this remodeling process, patient groups were divided into AF and SR both with or without ACE-I. Interestingly, there was a significantly lower expression of collagen I in AF with ACE-I (1.04 +/- 0.26) vs. AF without ACE-I treatment (2.07 +/- 0.24, p = 0.02). The microcapillaries were not diminished in AF with ACE-I (180 +/- 15) vs. SR with ACE-I (196 +/- 9), but there was a significant rarification in AF without ACE-I (123 +/- 18; p = 0.03). The expression of VEGF and bFGF did not reveal any significant differences. CONCLUSION In patients undergoing ACE-I treatment: atrial structural remodeling was attenuated and the loss of atrial microcapillaries was prevented.
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Affiliation(s)
- A Boldt
- University of Leipzig-Heart Center, Department of Cardiac Surgery, Strümpellstrasse 19, 04289 Leipzig, Germany.
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Lyon J, Alder S, Stone M, Anspaugh L, Holubkov R, Hoffman O, Hegmann K, Meikle W, Reading J, Scholl A, Sheng X, Simon S, Thomas B, White G. 409: Thyroid Disease Associated with Exposure to the Nevada Test Site Radiation – A Reevaluation Based on Corrected Dosimetry and Examination Data. Am J Epidemiol 2005. [DOI: 10.1093/aje/161.supplement_1.s103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J. Lyon
- University of Utah, Salt Lake City, UT 84108
| | - S Alder
- University of Utah, Salt Lake City, UT 84108
| | - M Stone
- University of Utah, Salt Lake City, UT 84108
| | - L Anspaugh
- University of Utah, Salt Lake City, UT 84108
| | - R Holubkov
- University of Utah, Salt Lake City, UT 84108
| | - O Hoffman
- University of Utah, Salt Lake City, UT 84108
| | - K Hegmann
- University of Utah, Salt Lake City, UT 84108
| | - W Meikle
- University of Utah, Salt Lake City, UT 84108
| | - J Reading
- University of Utah, Salt Lake City, UT 84108
| | - A Scholl
- University of Utah, Salt Lake City, UT 84108
| | - X Sheng
- University of Utah, Salt Lake City, UT 84108
| | - S Simon
- University of Utah, Salt Lake City, UT 84108
| | - B Thomas
- University of Utah, Salt Lake City, UT 84108
| | - G White
- University of Utah, Salt Lake City, UT 84108
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Zharnikov M, Shaporenko A, Paul A, Gölzhäuser A, Scholl A. X-ray Absorption Spectromicroscopy Studies for the Development of Lithography with a Monomolecular Resist. J Phys Chem B 2005; 109:5168-74. [PMID: 16863181 DOI: 10.1021/jp040649g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Soft X-ray absorption microscopy was applied to image and characterize molecular patterns produced by electron irradiation of aliphatic and aromatic thiol-derived self-assembled monolayers (SAMs) on Au substrates. The measurements were performed at all relevant absorption edges. The fabricated patterns could be clearly imaged with a lateral resolution better than 150 nm, which, for example, allowed us to distinguish a fine structure of 1 microm features. The X-ray absorption microspot spectra derived from different areas of the SAM patterns provided specific chemical information on pristine and irradiated areas and unexpected features in these patterns. The quality of the microspot spectra is comparable with that of the analogous X-ray absorption spectra acquired with standard equipment from homogeneous SAMs. In particular, a chemical transformation of the functional tail groups within the irradiated areas of the patterned aromatic SAMs could be directly monitored.
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Affiliation(s)
- M Zharnikov
- Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
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Wang J, Scholl A, Zheng H, Ogale SB, Viehland D, Schlom DG, Spaldin NA, Rabe KM, Wuttig M, Mohaddes L, Neaton J, Waghmare U, Zhao T, Ramesh R. Response to Comment on "Epitaxial BiFeO
3
Multiferroic Thin Film Heterostructures". Science 2005. [DOI: 10.1126/science.1103959] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- J. Wang
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - A. Scholl
- Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley CA, 94720, USA
| | - H. Zheng
- Department of Materials Science and Engineering, University of Maryland, College Park
| | - S. B. Ogale
- Department of Physics, University of Maryland, College Park
| | - D. Viehland
- Department of Materials Science and Engineering, Virginia Polytechnic Institute, Blacksburg, VA 24061, USA
| | - D. G. Schlom
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802–5055, USA
| | - N. A. Spaldin
- Materials Department, University of California, Santa Barbara, CA 93106–5050, USA
| | - K. M. Rabe
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - M. Wuttig
- Department of Materials Science and Engineering, University of Maryland, College Park
| | - L. Mohaddes
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, CA 94720
| | - J. Neaton
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley
| | | | - T. Zhao
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley
| | - R. Ramesh
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley
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38
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Wu YZ, Won C, Scholl A, Doran A, Zhao HW, Jin XF, Qiu ZQ. Magnetic stripe domains in coupled magnetic sandwiches. Phys Rev Lett 2004; 93:117205. [PMID: 15447377 DOI: 10.1103/physrevlett.93.117205] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Indexed: 05/24/2023]
Abstract
Magnetic stripe domains in the spin reorientation transition region are investigated in (Fe/Ni)/Cu(001) and Co/Cu/(Fe/Ni)/Cu(001) using photoemission electron microscopy. For (Fe/Ni)/Cu(001), the stripe domain width decreases exponentially as the Fe/Ni film approaches the spin reorientation transition point. For Co/Cu/(Fe/Ni)/Cu(001), the Fe/Ni stripe orientation is aligned with the Co in-plane magnetization, and the stripe domain width decreases exponentially with increasing the interlayer coupling between the Fe/Ni and Co films. By considering magnetic stripes within an in-plane magnetic field, we reveal a universal dependence of the stripe domain width on the magnetic anisotropy and on the interlayer coupling.
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Affiliation(s)
- Y Z Wu
- Department of Physics, University of California Berkeley, Berkeley California 94720, USA
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39
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Abstract
We present evidence for the creation of an exchange spring in an antiferromagnet due to exchange coupling to a ferromagnet. X-ray magnetic linear dichroism spectroscopy on single crystal Co/NiO(001) shows that a partial domain wall is wound up at the surface of the antiferromagnet when the adjacent ferromagnet is rotated by a magnetic field. We determine the interface exchange stiffness and the antiferromagnetic domain wall energy from the field dependence of the direction of the antiferromagnetic axis, the antiferromagnetic pendant to a ferromagnetic hysteresis loop. The existence of a planar antiferromagnetic domain wall, proven by our measurement, is a key assumption of most exchange bias models.
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Affiliation(s)
- A Scholl
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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40
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Abstract
Time-resolved x-ray imaging shows that the magnetization dynamics of a micron-sized pattern containing a ferromagnetic vortex is determined by its handedness, or chirality. The out-of-plane magnetization in the nanometer-scale vortex core induces a three-dimensional handedness in the planar magnetic structure, leading to a precessional motion of the core parallel to a subnanosecond field pulse. The core velocity was an order of magnitude higher than expected from the static susceptibility. These results demonstrate that handedness, already well known to be important in biological systems, plays an important role in the dynamics of microscopic magnets.
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Affiliation(s)
- S B Choe
- Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720, USA.
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41
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Zharnikov M, Ouchi Y, Hasegawa M, Scholl A. X-ray Absorption Spectromicroscopy Study of UV-Photoinduced Surface Modification and Anisotropy in Polyimide Films. J Phys Chem B 2003. [DOI: 10.1021/jp030782t] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Zharnikov
- Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany, Department of Chemistry, Nagoya University, Nagoya, 464-8602 Japan, IBM Research, Tokyo Research Laboratory, Yamato, Kanagawa 242-8502, Japan, and Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720
| | - Y. Ouchi
- Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany, Department of Chemistry, Nagoya University, Nagoya, 464-8602 Japan, IBM Research, Tokyo Research Laboratory, Yamato, Kanagawa 242-8502, Japan, and Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720
| | - M. Hasegawa
- Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany, Department of Chemistry, Nagoya University, Nagoya, 464-8602 Japan, IBM Research, Tokyo Research Laboratory, Yamato, Kanagawa 242-8502, Japan, and Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720
| | - A. Scholl
- Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany, Department of Chemistry, Nagoya University, Nagoya, 464-8602 Japan, IBM Research, Tokyo Research Laboratory, Yamato, Kanagawa 242-8502, Japan, and Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720
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42
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Won C, Wu YZ, Scholl A, Doran A, Kurahashi N, Zhao HW, Qiu ZQ. Magnetic phase transition in Co/Cu/Ni/Cu(100) and Co/Fe/Ni/Cu(100). Phys Rev Lett 2003; 91:147202. [PMID: 14611550 DOI: 10.1103/physrevlett.91.147202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2002] [Revised: 07/10/2003] [Indexed: 05/24/2023]
Abstract
Magnetic phase transitions in coupled magnetic sandwiches of Cu/Co/Cu/Ni/Cu(100) and Cu/Co/Fe/Ni/Cu(100) are investigated by photoemission electron microscopy. Element-specific magnetic domains are taken at room temperature to reveal the critical thickness at which the magnetic phase transition occurs. The results show that a coupled magnetic sandwich undergoes three types of magnetic phase transitions depending on the two ferromagnetic films' thickness. A phase diagram is constructed and explained in the process of constructing Monte Carlo simulations, which corroborate the experimental results.
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Affiliation(s)
- C Won
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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43
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Ohldag H, Scholl A, Nolting F, Arenholz E, Maat S, Young AT, Carey M, Stöhr J. Correlation between exchange bias and pinned interfacial spins. Phys Rev Lett 2003; 91:017203. [PMID: 12906569 DOI: 10.1103/physrevlett.91.017203] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2002] [Indexed: 05/24/2023]
Abstract
Using x-ray magnetic circular dichroism, we have detected the very interfacial spins that are responsible for the horizontal loop shift in three different exchange bias sandwiches, chosen because of their potential for device applications. The "pinned" uncompensated interfacial spins constitute only a fraction of a monolayer and do not rotate in an external magnetic field since they are tightly locked to the antiferromagnetic lattice. A simple extension of the Meiklejohn and Bean model is proposed to account quantitatively for the exchange bias fields in the three studied systems from the experimentally determined number of pinned moments and their sizes.
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Affiliation(s)
- H Ohldag
- Stanford Synchrotron Radiation Laboratory, P.O. Box 20450, Stanford, California 94309, USA.
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Minko S, Müller M, Usov D, Scholl A, Froeck C, Stamm M. Lateral versus perpendicular segregation in mixed polymer brushes. Phys Rev Lett 2002; 88:035502. [PMID: 11801069 DOI: 10.1103/physrevlett.88.035502] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2001] [Indexed: 05/23/2023]
Abstract
Grafting of incompatible polymers on a substrate prevents macrophase separation and the chains self-assemble laterally. Mixed brushes are exposed to different solvents and the morphology is observed via atomic force and x-ray photoemission microscopy. In a nonselective solvent the different species segregate into parallel cylinders ("ripple structure"). Upon exposure to a selective solvent, we encounter a transition to a "dimple" structure, in which the unfavored component forms clusters. Simultaneously, we observe an enhanced perpendicular segregation. The experimental observations are compared to self-consistent field calculations, where qualitative agreement is found.
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Affiliation(s)
- S Minko
- Institut für Polymerforschung Dresden e.V., Postfach 12 04 11, D-01005 Dresden, Germany
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45
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Ohldag H, Regan TJ, Stöhr J, Scholl A, Nolting F, Lüning J, Stamm C, Anders S, White RL. Spectroscopic identification and direct imaging of interfacial magnetic spins. Phys Rev Lett 2001; 87:247201. [PMID: 11736537 DOI: 10.1103/physrevlett.87.247201] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2001] [Indexed: 05/23/2023]
Abstract
Using x-ray absorption spectromicroscopy we have imaged the uncompensated spins induced at the surface of antiferromagnetic (AFM) NiO(100) by deposition of ferromagnetic (FM) Co. These spins align parallel to the AFM spins in NiO(100) and align the FM spins in Co. The uncompensated interfacial spins arise from an ultrathin CoNiOx layer that is formed upon Co deposition through reduction of the NiO surface. The interfacial Ni spins are discussed in terms of the "uncompensated spins" at AFM/FM interfaces long held responsible for coercivity increases and exchange bias. We find a direct correlation between their number and the size of the coercivity.
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Affiliation(s)
- H Ohldag
- Stanford Synchrotron Radiation Laboratory, P.O. Box 20450 Stanford, California 94309, USA
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46
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Ohldag H, Scholl A, Nolting F, Anders S, Hillebrecht FU, Stöhr J. Spin reorientation at the antiferromagnetic NiO(001) surface in response to an adjacent ferromagnet. Phys Rev Lett 2001; 86:2878-2881. [PMID: 11290062 DOI: 10.1103/physrevlett.86.2878] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2000] [Indexed: 05/23/2023]
Abstract
Polarization dependent x-ray photoemission electron microscopy was used to investigate the spin structure near the surface of an antiferromagnetic NiO(001) single crystal in response to the deposition of a thin ferromagnetic Co film. For the cleaved NiO surface we observe only a subset of bulklike antiferromagnetic domains which is attributed to minimization of dipolar energies. Upon Co deposition a spin reorientation near the NiO interface occurs, with the antiferromagnetic spins rotating in plane, parallel to the spins of the Co layer. Our results demonstrate that the spin configuration in an antiferromagnet near its interface with a ferromagnet may significantly deviate from that in the bulk antiferromagnet.
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Affiliation(s)
- H Ohldag
- Stanford Synchrotron Radiation Laboratory, P.O. Box 20450, Stanford, CA 94309, USA
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47
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Scholl A, Nolting F, Stöhr J, Lüning J, Seo JW, Locquet JP, Fompeyrine J, Anders S, Ohldag H, Padmore HA. Studies of the magnetic structure at the ferromagnet-antiferromagnet interface. J Synchrotron Radiat 2001; 8:101-104. [PMID: 11512704 DOI: 10.1107/s0909049500016460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2000] [Accepted: 11/07/2000] [Indexed: 05/23/2023]
Abstract
Antiferromagnetic layers are a scientifically challenging component in magnetoelectronic devices, such as magnetic sensors in hard-disk heads, or magnetic random-access memory (RAM) elements. In this paper, it is shown that photoelectron emission microscopy (PEEM) is capable of determining the magnetic structure at the interface of ferromagnets and antiferromagnets with high spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized soft X-rays from a synchrotron source, give rise to a magnetic image contrast. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO3, microscopically resolving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO3 and an adjacent Co layer results in a complete correlation of their magnetic domain structures. From field-dependent measurements, a unidirectional anisotropy resulting in a local exchange bias of up to 30 Oe in single domains could be deduced. The elemental specificity and the quantitative magnetic sensitivity render PEEM a perfect tool to study magnetic coupling effects in multilayered thin-film samples.
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Affiliation(s)
- A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, CA 94720, USA.
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Abstract
The drive to smaller and smaller computational devices demands control over the structure, composition, and magnetic properties of materials on a sub-100-nanometer scale. In his Perspective, Scholl highlights a report by Heinze et al., who have been able to image an antiferromagnetic Mn monolayer at atomic resolution using a technique called spin-polarized scanning tunneling microscopy. Because of its unrivaled resolution, this technique is likely to provide insights into magnetic interactions that are of fundamental importance to magnetic devices.
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49
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Thomas L, Luning J, Scholl A, Nolting F, Anders S, Stohr J, Parkin SS. Oscillatory decay of magnetization induced by domain-wall stray fields. Phys Rev Lett 2000; 84:3462-3465. [PMID: 11019115 DOI: 10.1103/physrevlett.84.3462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/1999] [Indexed: 05/23/2023]
Abstract
The demagnetization of a hard ferromagnetic layer via the fringing fields of domain walls created by reversing the moment of a neighboring soft ferromagnetic layer is explored experimentally. An unusual oscillatory decay of the magnetic moment of the hard layer is observed using structures in which the demagnetization occurs after a few hundred cycles. This surprising observation is confirmed on a microscopic scale by detailed imaging of the magnetization of the hard layer using high resolution photoemission electron microscopy and by micromagnetic simulations.
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Affiliation(s)
- L Thomas
- IBM Research Division, Almaden Research Center, San Jose, California 95120-6099, USA
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Scholl A, Stohr J, Luning J, Seo JW, Fompeyrine J, Siegwart H, Locquet J, Nolting F, Anders S, Fullerton EE, Scheinfein MR, Padmore HA. Observation of antiferromagnetic domains in epitaxial thin films. Science 2000; 287:1014-6. [PMID: 10669407 DOI: 10.1126/science.287.5455.1014] [Citation(s) in RCA: 277] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Antiferromagnetic domains in an epitaxial thin film, LaFeO(3) on SrTiO(3)(100), were observed using a high-spatial-resolution photoelectron emission microscope with contrast generated by the large x-ray magnetic linear dichroism effect at the multiplet-split L edge of Fe. The antiferromagnetic domains are linked to 90 degrees twinned crystallographic regions in the film. The Neel temperature of the thin film is reduced by 70 kelvin relative to the bulk material, and this reduction is attributed to epitaxial strain. These studies open the door for a microscopic understanding of the magnetic coupling across antiferromagnetic-ferromagnetic interfaces.
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Affiliation(s)
- A Scholl
- Advanced Light Source, 1 Cyclotron Road, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. IBM Research Division, Zurich Research Laboratory
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