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De Souza LR, Berger H, Retnakaran R, Vlachou PA, Maguire JL, Nathens AB, Connelly PW, Ray JG. Hepatic fat and abdominal adiposity in early pregnancy together predict impaired glucose homeostasis in mid-pregnancy. Nutr Diabetes 2016; 6:e229. [PMID: 27643724 PMCID: PMC5048015 DOI: 10.1038/nutd.2016.39] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 06/06/2016] [Accepted: 07/04/2016] [Indexed: 12/20/2022] Open
Abstract
Hepatic fat and abdominal adiposity individually reflect insulin resistance, but their combined effect on glucose homeostasis in mid-pregnancy is unknown. A cohort of 476 pregnant women prospectively underwent sonographic assessment of hepatic fat and visceral (VAT) and total (TAT) adipose tissue at 11–14 weeks' gestation. Logistic regression was used to assess the relation between the presence of maternal hepatic fat and/or the upper quartile (Q) of either VAT or TAT and the odds of developing the composite outcome of impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or gestational diabetes mellitus at 24–28 weeks' gestation, based on a 75 g OGTT. Upon adjusting for maternal age, ethnicity, family history of DM and body mass index (BMI), the co-presence of hepatic fat and quartile 4 (Q4) of VAT (adjusted odds ratio (aOR) 6.5, 95% CI: 2.3–18.5) or hepatic fat and Q4 of TAT (aOR 7.8 95% CI 2.8–21.7) were each associated with the composite outcome, relative to women with neither sonographic feature. First-trimester sonographic evidence of maternal hepatic fat and abdominal adiposity may independently predict the development of impaired glucose homeostasis and GDM in mid-pregnancy.
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Bapat P, Pinto LSR, Lubetsky A, Aleksa K, Berger H, Koren G, Ito S. Examining the transplacental passage of apixaban using the dually perfused human placenta. J Thromb Haemost 2016; 14:1436-41. [PMID: 27149680 DOI: 10.1111/jth.13353] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/18/2016] [Indexed: 12/16/2022]
Abstract
UNLABELLED Essentials Apixaban is a novel oral anticoagulant that has not been studied in pregnant patients. Our objective was to determine the rate and extent of the placental transfer of apixaban. Apixaban rapidly crosses the ex vivo term human placenta from maternal to fetal circulation. Fetal apixaban levels in vivo are estimated to be 35-90% of the corresponding maternal levels. SUMMARY Background Apixaban is a novel oral anticoagulant that is increasingly being prescribed to women of reproductive age. However, information regarding its placental transfer is non-existent. Objective To determine the rate and extent of placental transfer of apixaban, using the human placenta ex vivo. Methods Placentae collected after Caesarean or vaginal delivery of healthy term infants were perfused in the respective maternal and fetal circulation. At the start of the experiment, apixaban was added to the maternal circulation at a concentration of 150 ng mL(-1) , and samples from maternal and fetal reservoirs were collected over 3 h. Results There was a rapid decline of apixaban in the maternal compartment, followed by emergence in the fetal compartment with a median fetal-to-maternal drug concentration ratio of 0.77 (interquartile range [IQR], 0.76-0.81) and fetal concentration of 39.0 ng mL(-1) (IQR, 36.8-40.6) after 3 h (n = 5). The perfusion results were subsequently adjusted to account for differences in the concentration of plasma proteins in maternal and fetal blood, as apixaban remains highly bound to albumin and alpha-1 acid glycoprotein. After the adjustment, the predicted fetal-to-maternal ratio of total (bound plus unbound) apixaban concentrations in vivo ranged from 0.35 to 0.90. Conclusions We conclude that unbound apixaban rapidly crosses from the maternal to fetal circulation. We further predict that total apixaban concentrations in cord blood in vivo are 35-90% of the corresponding maternal levels, suggesting that apixaban could have a possible adverse effect on fetal and neonatal coagulation.
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Zhang SL, Bauer A, Burn DM, Milde P, Neuber E, Eng LM, Berger H, Pfleiderer C, van der Laan G, Hesjedal T. Multidomain Skyrmion Lattice State in Cu2OSeO3. NANO LETTERS 2016; 16:3285-3291. [PMID: 27070961 DOI: 10.1021/acs.nanolett.6b00845] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Magnetic skyrmions in chiral magnets are nanoscale, topologically protected magnetization swirls that are promising candidates for spintronics memory carriers. Therefore, observing and manipulating the skyrmion state on the surface level of the materials are of great importance for future applications. Here, we report a controlled way of creating a multidomain skyrmion state near the surface of a Cu2OSeO3 single crystal, observed by soft resonant elastic X-ray scattering. This technique is an ideal tool to probe the magnetic order at the L3 edge of 3d metal compounds giving an average depth sensitivity of ∼50 nm. The single-domain 6-fold-symmetric skyrmion lattice can be broken up into domains, overcoming the propagation directions imposed by the cubic anisotropy by applying the magnetic field in directions deviating from the major cubic axes. Our findings open the door to a new way to manipulate and engineer the skyrmion state locally on the surface or on the level of individual skyrmions, which will enable applications in the future.
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Manzoni G, Sterzi A, Crepaldi A, Diego M, Cilento F, Zacchigna M, Bugnon P, Berger H, Magrez A, Grioni M, Parmigiani F. Ultrafast Optical Control of the Electronic Properties of ZrTe₅. PHYSICAL REVIEW LETTERS 2015; 115:207402. [PMID: 26613470 DOI: 10.1103/physrevlett.115.207402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Indexed: 06/05/2023]
Abstract
We report on the temperature dependence of the ZrTe(5) electronic properties, studied at equilibrium and out of equilibrium, by means of time and angle resolved photoelectron spectroscopy. Our results unveil the dependence of the electronic band structure across the Fermi energy on the sample temperature. This finding is regarded as the dominant mechanism responsible for the anomalous resistivity observed at T*∼160 K along with the change of the charge carrier character from holelike to electronlike. Having addressed these long-lasting questions, we prove the possibility to control, at the ultrashort time scale, both the binding energy and the quasiparticle lifetime of the valence band. These experimental evidences pave the way for optically controlling the thermoelectric and magnetoelectric transport properties of ZrTe(5).
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Ruff E, Lunkenheimer P, Loidl A, Berger H, Krohns S. Magnetoelectric effects in the skyrmion host material Cu2OSeO3. Sci Rep 2015; 5:15025. [PMID: 26446514 PMCID: PMC4597216 DOI: 10.1038/srep15025] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/16/2015] [Indexed: 11/30/2022] Open
Abstract
Insulating helimagnetic Cu2OSeO3 shows sizeable magnetoelectric effects in its skyrmion phase. Using magnetization measurements, magneto-current analysis and dielectric spectroscopy, we provide a thorough investigation of magnetoelectric coupling, polarization and dielectric constants of the ordered magnetic and polar phases of single-crystalline Cu2OSeO3 in external magnetic fields up to 150 mT and at temperatures below 60 K. From these measurements we construct a detailed phase diagram. Especially, the skyrmion phase and the metamagnetic transition of helical to conical spin order are characterized in detail. Finally we address the question if there is any signature of polar order that can be switched by an external electric field, which would imply multiferroic behaviour of Cu2OSeO3.
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Müller-Nordhorn J, Muckelbauer R, Englert H, Grittner U, Berger H, Prugger C, Wegscheider K, Willich SN. Longitudinal Association Between Body Mass Index and Health-Related Quality of Life. Int J Epidemiol 2015. [DOI: 10.1093/ije/dyv096.343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Vogel H, Blöcher A, Wegmann U, Berger H, Faller H. Nachbefragung von Rehabilitanden zum Reha- und Entlassungsmanagement als Baustein der Qualitätssicherung in der Medizinischen Rehabilitation. DAS GESUNDHEITSWESEN 2015. [DOI: 10.1055/s-0035-1563232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ahnert J, Schuler M, Legner R, Berger H, Vogel H. Anträge auf psychosomatische Rehabilitation – Häufigkeit, Qualität und Befürwortungsrate im Vergleich zu Anträgen auf somatische Rehabilitation. DAS GESUNDHEITSWESEN 2015. [DOI: 10.1055/s-0035-1563228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Moser S, Fatale S, Krüger P, Berger H, Bugnon P, Magrez A, Niwa H, Miyawaki J, Harada Y, Grioni M. Electron-Phonon Coupling in the Bulk of Anatase TiO2 Measured by Resonant Inelastic X-Ray Spectroscopy. PHYSICAL REVIEW LETTERS 2015; 115:096404. [PMID: 26371668 DOI: 10.1103/physrevlett.115.096404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Indexed: 06/05/2023]
Abstract
We investigate the polaronic ground state of anatase TiO2 by bulk-sensitive resonant inelastic x-ray spectroscopy (RIXS) at the Ti L3 edge. We find that the formation of the polaron cloud involves a single 95 meV phonon along the c axis, in addition to the 108 meV ab-plane mode previously identified by photoemission. The coupling strength to both modes is the same within error bars, and it is unaffected by the carrier density. These data establish RIXS as a directional bulk-sensitive probe of electron-phonon coupling in solids.
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Pregelj M, Zorko A, Zaharko O, Nojiri H, Berger H, Chapon LC, Arčon D. Spin-stripe phase in a frustrated zigzag spin-1/2 chain. Nat Commun 2015; 6:7255. [PMID: 26068618 PMCID: PMC4490353 DOI: 10.1038/ncomms8255] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 04/21/2015] [Indexed: 11/09/2022] Open
Abstract
Motifs of periodic modulations are encountered in a variety of natural systems, where at least two rival states are present. In strongly correlated electron systems, such behaviour has typically been associated with competition between short- and long-range interactions, for example, between exchange and dipole-dipole interactions in the case of ferromagnetic thin films. Here we show that spin-stripe textures may develop also in antiferromagnets, where long-range dipole-dipole magnetic interactions are absent. A comprehensive analysis of magnetic susceptibility, high-field magnetization, specific heat and neutron diffraction measurements unveils β-TeVO4 as a nearly perfect realization of a frustrated (zigzag) ferromagnetic spin-1/2 chain. Notably, a narrow spin-stripe phase develops at elevated magnetic fields due to weak frustrated short-range interchain exchange interactions, possibly assisted by the symmetry-allowed electric polarization. This concept provides an alternative route for the stripe formation in strongly correlated electron systems and may help understanding of other widespread, yet still elusive, stripe-related phenomena.
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Schwarze T, Waizner J, Garst M, Bauer A, Stasinopoulos I, Berger H, Pfleiderer C, Grundler D. Universal helimagnon and skyrmion excitations in metallic, semiconducting and insulating chiral magnets. NATURE MATERIALS 2015; 14:478-483. [PMID: 25730395 DOI: 10.1038/nmat4223] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
Nearly seven decades of research on microwave excitations of magnetic materials have led to a wide range of applications in electronics. The recent discovery of topological spin solitons in chiral magnets, so-called skyrmions, promises high-frequency devices that exploit the exceptional emergent electrodynamics of these compounds. Therefore, an accurate and unified quantitative account of their resonant response is key. Here, we report all-electrical spectroscopy of the collective spin excitations in the metallic, semiconducting and insulating chiral magnets MnSi, Fe1-xCoxSi and Cu2OSeO3, respectively, using broadband coplanar waveguides. By taking into account dipolar interactions, we achieve a precise quantitative modelling across the entire magnetic phase diagrams using two material-specific parameters that quantify the chiral and the critical field energy. The universal behaviour sets the stage for purpose-designed applications based on the resonant response of chiral magnets with tailored electric conductivity and an unprecedented freedom for an integration with electronics.
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Baber M, Chaudhry S, Kelly L, Ross C, Carleton B, Berger H, Koren G. The pharmacogenetics of codeine pain relief in the postpartum period. THE PHARMACOGENOMICS JOURNAL 2015; 15:430-5. [DOI: 10.1038/tpj.2015.3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/16/2014] [Accepted: 12/02/2014] [Indexed: 11/10/2022]
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Cacho C, Crepaldi A, Battiato M, Braun J, Cilento F, Zacchigna M, Richter MC, Heckmann O, Springate E, Liu Y, Dhesi SS, Berger H, Bugnon P, Held K, Grioni M, Ebert H, Hricovini K, Minár J, Parmigiani F. Momentum-resolved spin dynamics of bulk and surface excited States in the topological insulator Bi(2)Se(3). PHYSICAL REVIEW LETTERS 2015; 114:097401. [PMID: 25793848 DOI: 10.1103/physrevlett.114.097401] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Indexed: 06/04/2023]
Abstract
The prospect of optically inducing and controlling a spin-polarized current in spintronic devices has generated wide interest in the out-of-equilibrium electronic and spin structure of topological insulators. In this Letter we show that only measuring the spin intensity signal over several orders of magnitude by spin-, time-, and angle-resolved photoemission spectroscopy can provide a comprehensive description of the optically excited electronic states in Bi_{2}Se_{3}. Our experiments reveal the existence of a surface resonance state in the second bulk band gap that is benchmarked by fully relativistic ab initio spin-resolved photoemission calculations. We propose that the newly reported state plays a major role in the ultrafast dynamics of the system, acting as a bottleneck for the interaction between the topologically protected surface state and the bulk conduction band. In fact, the spin-polarization dynamics in momentum space show that these states display macroscopically different temperatures and, more importantly, different cooling rates over several picoseconds.
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Guarise M, Piazza BD, Berger H, Giannini E, Schmitt T, Rønnow HM, Sawatzky GA, van den Brink J, Altenfeld D, Eremin I, Grioni M. Anisotropic softening of magnetic excitations along the nodal direction in superconducting cuprates. Nat Commun 2014; 5:5760. [DOI: 10.1038/ncomms6760] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 11/05/2014] [Indexed: 11/09/2022] Open
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Boschini F, Hedayat H, Dallera C, Farinello P, Manzoni C, Magrez A, Berger H, Cerullo G, Carpene E. An innovative Yb-based ultrafast deep ultraviolet source for time-resolved photoemission experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:123903. [PMID: 25554305 DOI: 10.1063/1.4903347] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Time- and angle-resolved photoemission spectroscopy is a powerful technique to study ultrafast electronic dynamics in solids. Here, an innovative optical setup based on a 100-kHz Yb laser source is presented. Exploiting non-collinear optical parametric amplification and sum-frequency generation, ultrashort pump (hν = 1.82 eV) and ultraviolet probe (hν = 6.05 eV) pulses are generated. Overall temporal and instrumental energy resolutions of, respectively, 85 fs and 50 meV are obtained. Time- and angle-resolved measurements on BiTeI semiconductor are presented to show the capabilities of the setup.
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Ozerov M, Romhányi J, Belesi M, Berger H, Ansermet JP, van den Brink J, Wosnitza J, Zvyagin SA, Rousochatzakis I. Establishing the fundamental magnetic interactions in the chiral Skyrmionic Mott insulator Cu(2)OSeO(3) by terahertz electron spin resonance. PHYSICAL REVIEW LETTERS 2014; 113:157205. [PMID: 25375739 DOI: 10.1103/physrevlett.113.157205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Indexed: 05/26/2023]
Abstract
The recent discovery of Skyrmions in Cu(2)OSeO(3) has established a new platform to create and manipulate Skyrmionic spin textures. We use high-field electron spin resonance with a terahertz free-electron laser and pulsed magnetic fields up to 64 T to probe and quantify its microscopic spin-spin interactions. In addition to the previously observed long-wavelength Goldstone mode, this technique probes also the high-energy part of the excitation spectrum which is inaccessible by standard low-frequency electron spin resonance. Fitting the behavior of the observed modes in magnetic field to a theoretical framework establishes experimentally that the fundamental magnetic building blocks of this Skyrmionic magnet are rigid, highly entangled and weakly coupled tetrahedra.
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White JS, Prša K, Huang P, Omrani AA, Zivković I, Bartkowiak M, Berger H, Magrez A, Gavilano JL, Nagy G, Zang J, Rønnow HM. Electric-field-induced Skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3. PHYSICAL REVIEW LETTERS 2014; 113:107203. [PMID: 25238382 DOI: 10.1103/physrevlett.113.107203] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Indexed: 06/03/2023]
Abstract
Uniquely in Cu2OSeO3, the Skyrmions, which are topologically protected magnetic spin vortexlike objects, display a magnetoelectric coupling and can be manipulated by externally applied electric (E) fields. Here, we explore the E-field coupling to the magnetoelectric Skyrmion lattice phase, and study the response using neutron scattering. Giant E-field induced rotations of the Skyrmion lattice are achieved that span a range of ∼25°. Supporting calculations show that an E-field-induced Skyrmion distortion lies behind the lattice rotation. Overall, we present a new approach to Skyrmion control that makes no use of spin-transfer torques due to currents of either electrons or magnons.
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VanGennep D, Maiti S, Graf D, Tozer SW, Martin C, Berger H, Maslov DL, Hamlin JJ. Pressure tuning the Fermi level through the Dirac point of giant Rashba semiconductor BiTeI. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:342202. [PMID: 25090658 DOI: 10.1088/0953-8984/26/34/342202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report measurements of Shubnikov-de Haas oscillations in the giant Rashba semiconductor BiTeI under applied pressures up to ∼2 GPa. We observe one high frequency oscillation at all pressures and one low frequency oscillation that emerges between ∼0.3-0.7 GPa indicating the appearance of a second small Fermi surface. BiTeI has a conduction band bottom that is split into two sub-bands due to the strong Rashba coupling, resulting in a 'Dirac point'. Our results suggest that the chemical potential starts below the Dirac point in the conduction band at ambient pressure and moves upward, crossing it as pressure is increased. The presence of the chemical potential above this Dirac point results in two Fermi surfaces. We present a simple model that captures this effect and can be used to understand the pressure dependence of our sample parameters. These extracted parameters are in quantitative agreement with first-principles calculations and other experiments. The parameters extracted via our model support the notion that pressure brings the system closer to the predicted topological quantum phase transition.
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Hildebrand B, Didiot C, Novello AM, Monney G, Scarfato A, Ubaldini A, Berger H, Bowler DR, Renner C, Aebi P. Doping nature of native defects in 1T-TiSe2. PHYSICAL REVIEW LETTERS 2014; 112:197001. [PMID: 24877961 DOI: 10.1103/physrevlett.112.197001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Indexed: 06/03/2023]
Abstract
The transition-metal dichalcogenide 1T-TiSe2 is a quasi-two-dimensional layered material with a charge density wave (CDW) transition temperature of T(CDW) ≈ 200 K. Self-doping effects for crystals grown at different temperatures introduce structural defects, modify the temperature-dependent resistivity, and strongly perturbate the CDW phase. Here, we study the structural and doping nature of such native defects combining scanning tunneling microscopy or spectroscopy and ab initio calculations. The dominant native single atom dopants we identify in our single crystals are intercalated Ti atoms, Se vacancies, and Se substitutions by residual iodine and oxygen.
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Shiohira S, Yoshida T, Sugiura H, Nishida M, Nitta K, Tsuchiya K, Grampp S, Goppelt-Strube M, Eckardt KU, Schodel J, Kang SW, Kim Y, Seo SK, Kim T, Ong S, Yang WS, Han NJ, Lee JM, Baek CH, Park SK, Kemter E, Aigner B, Wanke R, Troyano Suarez N, Olmos Centenero G, Mora I, Griera M, Cano JL, Martin P, Zamora J, Ruiz-Torres MP, Falke LL, Leask A, Lyons K, Nguyen TQ, Goldschmeding R, Park SK, Kim D, Lee AS, Jung YJ, Yang KH, Lee S, Kim W, Kim W, Kang KP, Garcia-Jerez A, Luengo-Rodriguez A, Ramirez-Chamond R, Carracedo J, Medrano-Andres D, Rodriguez-Puyol D, Calleros L, Kim HW, Park SK, Yang WS, Lee SK, Chang JW, Seo JW, Lee CT, Chou CA, Lee YT, Ng HY, Sanchez-Nino MD, Fernandez-Fernandez B, Perez-Gomez MV, Poveda J, Sanz AB, Cannata-Ortiz P, Egido J, Selgas R, Ortiz A, Ma SK, Kim IJ, Kim CS, Bae EH, Kim SW, Kokeny G, Boo'Si M, Fazekas K, Rosivall L, Mozes MM, Mijuskovic M, Ulrich C, Berger H, Trojanowicz B, Kohler F, Wolf A, Seibert E, Fiedler R, Markau S, Glomb M, Girndt M, Lajdova I, Spustova V, Oksa A, Chorvat D, Marcek Chorvatova A, Choi SO, Kim JS, Han BG, Yang JW, Liu S, Lv J, Chang R, Su F, Liang W, Zawada AM, Rogacev KS, Hundsdorfer J, Sester U, Fliser D, Heine GH, Chen JS, Cheng CW, Chang LC, Wu CZ, Novaes AS, Borges FT, Boim MA, Tramonti G, Romiti N, Chieli E, Hamahata S, Nagasawa Y, Kawabe M, Kida A, Yahiro M, Nanami M, Hasuike Y, Kuragano T, Nakasho K, Ohyama H, Nakanishi T, Tanaka S, Yano S, Sugimoto T, Bae E, Stevens KK, Hillyard DZ, Delles C, Jardine AG, Burke M, Morais C, Soyer P, Sinnya S, Winterford C, Oliver K, Lambie D, Staatz C, Carroll R, Campbell S, Isbel N, Felaco P, Pesce M, Patruno A, Sirolli V, Speranza L, Amoroso L, Franceschelli S, Bonomini M, Thilo F, Zakrzewicz A, Tepel M, Thilo F, Zakrzewicz A, Tepel M, Liu S, Li Y, Liang W, Su F, Wang B. CELL SIGNALLING AND APOPTOSIS. Nephrol Dial Transplant 2014. [DOI: 10.1093/ndt/gfu161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Wildgruber M, Borgmeyer S, Ettl J, Meier R, Berger H. Radiologische Implantation zentralvenöser Portkathetersysteme am Unterarm – eine retrospektive monozentrische Analyse von 1722 Patienten. ROFO-FORTSCHR RONTG 2014. [DOI: 10.1055/s-0034-1373064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Choi KY, Choi IH, Lemmens P, van Tol J, Berger H. Magnetic, structural, and electronic properties of the multiferroic compound FeTe₂O₅Br with geometrical frustration. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:086001. [PMID: 24501196 DOI: 10.1088/0953-8984/26/8/086001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report electron spin resonance (ESR), Raman scattering, and interband absorption measurements of the multiferroic FeTe₂O₅Br with two successive magnetic transitions at T(N1) = 11.0 K and T(N2) = 10.5 K. ESR measurements show all characteristics of a low-dimensional frustrated magnet: (i) the appearance of an antiferromagnetic resonance (AFMR) mode at 40 K, a much higher temperature than T(N1), and (ii) a weaker temperature dependence of the AFMR linewidth than in classical magnets, ΔH(pp)(T) ∝ T(n) with n = 2.2-2.3. Raman spectra at ambient pressure show a large variation of phonon intensities with temperature while there are no appreciable changes in phonon numbers and frequencies. This demonstrates the significant role of the polarizable Te⁴⁺ lone pairs in inducing multiferroicity. Under pressure at P = 2.12-3.04 GPa Raman spectra undergo drastic changes and absorption spectra exhibit an abrupt drop of a band gap. This evidences a pressure-induced structural transition related to changes of the electronic states at high pressures.
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Ilakovac V, Guarise M, Grioni M, Schmitt T, Zhou K, Braicovich L, Ghiringhelli G, Strocov VN, Berger H. Opening of a Peierls gap in BaVS3 probed by V L3 edge resonant inelastic x-ray scattering. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:505602. [PMID: 24275702 DOI: 10.1088/0953-8984/25/50/505602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
V L3 edge resonant inelastic x-ray scattering measurements performed on high quality BaVS3 single crystals reveal that the intra-t2g dd excitations close to the elastic peak are suppressed below the metal-insulator transition induced by the Peierls instability. The depletion of electronic states close to the Fermi level represents a direct observation of the opening of a charge gap inside the t2g manifold.
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Xi X, Ma C, Liu Z, Chen Z, Ku W, Berger H, Martin C, Tanner DB, Carr GL. Signatures of a pressure-induced topological quantum phase transition in BiTeI. PHYSICAL REVIEW LETTERS 2013; 111:155701. [PMID: 24160613 DOI: 10.1103/physrevlett.111.155701] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 06/15/2013] [Indexed: 06/02/2023]
Abstract
We report the observation of two signatures of a pressure-induced topological quantum phase transition in the polar semiconductor BiTeI using x-ray powder diffraction and infrared spectroscopy. The x-ray data confirm that BiTeI remains in its ambient-pressure structure up to 8 GPa. The lattice parameter ratio c/a shows a minimum between 2.0-2.9 GPa, indicating an enhanced c-axis bonding through p(z) band crossing as expected during the transition. Over the same pressure range, the infrared spectra reveal a maximum in the optical spectral weight of the charge carriers, reflecting the closing and reopening of the semiconducting band gap. Both of these features are characteristics of a topological quantum phase transition and are consistent with a recent theoretical proposal.
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Tournier-Colletta C, Moreschini L, Autès G, Moser S, Crepaldi A, Berger H, Walter AL, Kim KS, Bostwick A, Monceau P, Rotenberg E, Yazyev OV, Grioni M. Electronic instability in a zero-gap semiconductor: the charge-density wave in (TaSe4)2I. PHYSICAL REVIEW LETTERS 2013; 110:236401. [PMID: 25167517 DOI: 10.1103/physrevlett.110.236401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Indexed: 06/03/2023]
Abstract
We report a comprehensive study of the paradigmatic quasi-1D compound (TaSe(4))(2)I performed by means of angle-resolved photoemission spectroscopy (ARPES) and first-principles electronic structure calculations. We find it to be a zero-gap semiconductor in the nondistorted structure, with non-negligible interchain coupling. Theory and experiment support a Peierls-like scenario for the charge-density wave formation below T(CDW)=263 K, where the incommensurability is a direct consequence of the finite interchain coupling. The formation of small polarons, strongly suggested by the ARPES data, explains the puzzling semiconductor-to-semiconductor transition observed in transport at T(CDW).
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