1
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Almeida TP, Lequeux S, Palomino A, Sousa RC, Fruchart O, Prejbeanu IL, Dieny B, Masseboeuf A, Cooper D. Quantitative Visualization of Thermally Enhanced Perpendicular Shape Anisotropy STT-MRAM Nanopillars. NANO LETTERS 2022; 22:4000-4005. [PMID: 35576455 DOI: 10.1021/acs.nanolett.2c00597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Perpendicular shape anisotropy (PSA) offers a practical solution to downscale spin-transfer torque magnetoresistive random-access memory (STT-MRAM) beyond the sub-20 nm technology node while retaining thermal stability. However, our understanding of the thermomagnetic behavior of PSA-STT-MRAM is often indirect, relying on magnetoresistance measurements and micromagnetic modeling. Here, the magnetism of a NiFe PSA-STT-MRAM nanopillar is investigated using off-axis electron holography, providing spatially resolved magnetic information as a function of temperature. Magnetic induction maps reveal the micromagnetic configuration of the NiFe storage layer (∼60 nm high, ≤20 nm diameter), confirming the PSA induced by its 3:1 aspect ratio. In situ heating demonstrates that the PSA of the storage layer is maintained up to at least 250 °C, and direct quantitative measurements reveal a moderate decrease of magnetic induction. Hence, this study shows explicitly that PSA provides significant stability in STT-MRAM applications that require reliable performance over a range of operating temperatures.
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Affiliation(s)
- Trevor P Almeida
- University of Grenoble Alpes, CEA, Leti, F-38000 Grenoble, France
- SUPA, School of Physics and Astronomy, University of Glasgow, Glascow G12 8QQ, United Kingdom
| | - Steven Lequeux
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Alvaro Palomino
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Ricardo C Sousa
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Olivier Fruchart
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Ioan-Lucian Prejbeanu
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Bernard Dieny
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Aurélien Masseboeuf
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - David Cooper
- University of Grenoble Alpes, CEA, Leti, F-38000 Grenoble, France
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2
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Thébault C, Marmiesse M, Naud C, Pernet-Gallay K, Billiet E, Joisten H, Dieny B, Carrière M, Hou Y, Morel R. Magneto-mechanical treatment of human glioblastoma cells with engineered iron oxide powder microparticles for triggering apoptosis. NANOSCALE ADVANCES 2021; 3:6213-6222. [PMID: 36133951 PMCID: PMC9418695 DOI: 10.1039/d1na00461a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/21/2021] [Indexed: 05/03/2023]
Abstract
In nanomedicine, treatments based on physical mechanisms are more and more investigated and are promising alternatives for challenging tumor therapy. One of these approaches, called magneto-mechanical treatment, consists in triggering cell death via the vibration of anisotropic magnetic particles, under a low frequency magnetic field. In this work, we introduce a new type of easily accessible magnetic microparticles (MMPs) and study the influence of their surface functionalization on their ability to induce such an effect, and its mechanism. We prepared anisotropic magnetite microparticles by liquid-phase ball milling of a magnetite powder. These particles are completely different from the often-used SPIONs: they are micron-size, ferromagnetic, with a closed-flux magnetic structure reminiscent of that of vortex particles. The magnetic particles were covered with a silica shell, and grafted with PEGylated ligands with various physicochemical properties. We investigated both bare and coated particles' in vitro cytotoxicity, and compared their efficiency to induce U87-MG human glioblastoma cell apoptosis under a low frequency rotating magnetic field (RMF). Our results indicated that (1) the magneto-mechanical treatment with bare MMPs induces a rapid decrease in cell viability whereas the effect is slower with PEGylated particles; (2) the number of apoptotic cells after magneto-mechanical treatment is higher with PEGylated particles; (3) a lower frequency of RMF (down to 2 Hz) favors the apoptosis. These results highlight a difference in the cell death mechanism according to the properties of particles used - the rapid cell death observed with the bare MMPs indicates a death pathway via necrosis, while PEGylated particles seem to favor apoptosis.
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Affiliation(s)
- C Thébault
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-SyMMES 38000 Grenoble France
| | - M Marmiesse
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
| | - C Naud
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
| | - K Pernet-Gallay
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, CEA, Grenoble Institut Neurosciences Grenoble France
| | - E Billiet
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
| | - H Joisten
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
- Univ. Grenoble Alpes, CEA, LETI 38000 Grenoble France
| | - B Dieny
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
| | - M Carrière
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-SyMMES 38000 Grenoble France
| | - Y Hou
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-SyMMES 38000 Grenoble France
| | - R Morel
- Univ. Grenoble Alpes, CEA, CNRS, Spintec 38000 Grenoble France
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de Groot LV, Fabian K, Béguin A, Kosters ME, Cortés‐Ortuño D, Fu RR, Jansen CML, Harrison RJ, van Leeuwen T, Barnhoorn A. Micromagnetic Tomography for Paleomagnetism and Rock-Magnetism. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2021; 126:e2021JB022364. [PMID: 35866100 PMCID: PMC9286618 DOI: 10.1029/2021jb022364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 09/11/2021] [Accepted: 09/22/2021] [Indexed: 06/15/2023]
Abstract
Our understanding of the past behavior of the geomagnetic field arises from magnetic signals stored in geological materials, e.g., (volcanic) rocks. Bulk rock samples, however, often contain magnetic grains that differ in chemistry, size, and shape; some of them record the Earth's magnetic field well, others are unreliable. The presence of a small amount of adverse behaved magnetic grains in a sample may already obscure important information on the past state of the geomagnetic field. Recently it was shown that it is possible to determine magnetizations of individual grains in a sample by combining X-ray computed tomography and magnetic surface scanning measurements. Here we establish this new Micromagnetic Tomography (MMT) technique and make it suitable for use with different magnetic scanning techniques, and for both synthetic and natural samples. We acquired reliable magnetic directions by selecting subsets of grains in a synthetic sample, and we obtained rock-magnetic information of individual grains in a volcanic sample. This illustrates that MMT opens up entirely new venues of paleomagnetic and rock-magnetic research. MMT's unique ability to determine the magnetization of individual grains in a nondestructive way allows for a systematic analysis of how geological materials record and retain information on the past state of the Earth's magnetic field. Moreover, by interpreting only the contributions of known magnetically well-behaved grains in a sample, MMT has the potential to unlock paleomagnetic information from even the most complex, crucial, or valuable recorders that current methods are unable to recover.
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Affiliation(s)
- Lennart V. de Groot
- Paleomagnetic laboratory Fort HoofddijkFaculty of GeosciencesUtrecht UniversityUtrechtThe Netherlands
| | - Karl Fabian
- Department of Geoscience and PetroleumNorwegian University of Science and TechnologyTrondheimNorway
| | - Annemarieke Béguin
- Paleomagnetic laboratory Fort HoofddijkFaculty of GeosciencesUtrecht UniversityUtrechtThe Netherlands
- Department of Geoscience and PetroleumNorwegian University of Science and TechnologyTrondheimNorway
| | - Martha E. Kosters
- Paleomagnetic laboratory Fort HoofddijkFaculty of GeosciencesUtrecht UniversityUtrechtThe Netherlands
| | - David Cortés‐Ortuño
- Paleomagnetic laboratory Fort HoofddijkFaculty of GeosciencesUtrecht UniversityUtrechtThe Netherlands
| | - Roger R. Fu
- Department of Earth and Planetary SciencesHarvard UniversityCambridgeMAUSA
| | - Chloë M. L. Jansen
- Paleomagnetic laboratory Fort HoofddijkFaculty of GeosciencesUtrecht UniversityUtrechtThe Netherlands
| | | | - Tristan van Leeuwen
- Mathematical InstituteFaculty of SciencesUtrecht UniversityUtrechtThe Netherlands
- Department of Computational ImagingCentrum Wiskunde & Informatica (CWI)AmsterdamThe Netherlands
| | - Auke Barnhoorn
- Department of Geoscience and EngineeringFaculty of Civil Engineering and GeosciencesDelft University of TechnologyDelftThe Netherlands
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ALMEIDA T, MCGROUTHER D, KOVÁCS A, DUNIN‐BORKOWSKI R, MCVITIE S. Effect of annealing on the magnetic states of FEBID‐grown cobalt nanopatterns examined by off‐axis electron holography. J Microsc 2020; 279:217-221. [DOI: 10.1111/jmi.12869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/12/2019] [Accepted: 01/23/2020] [Indexed: 11/29/2022]
Affiliation(s)
- T. ALMEIDA
- School of Physics and AstronomyUniversity of Glasgow Glasgow U.K
| | - D. MCGROUTHER
- School of Physics and AstronomyUniversity of Glasgow Glasgow U.K
| | - A. KOVÁCS
- Ernst Ruska‐Centre for Microscopy and Spectroscopy with Electrons (ER‐C), Peter Grünberg InstituteForschungszentrum Jülich Jülich Germany
| | - R. DUNIN‐BORKOWSKI
- Ernst Ruska‐Centre for Microscopy and Spectroscopy with Electrons (ER‐C), Peter Grünberg InstituteForschungszentrum Jülich Jülich Germany
| | - S. MCVITIE
- School of Physics and AstronomyUniversity of Glasgow Glasgow U.K
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Ter Maat GW, Pennock GM, de Groot LV. A chemical, crystallographic and magnetic characterisation of individual iron-oxide grains in Hawaiian lavas. Sci Data 2018; 5:180162. [PMID: 30106393 PMCID: PMC6091240 DOI: 10.1038/sdata.2018.162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 06/21/2018] [Indexed: 11/18/2022] Open
Abstract
Our knowledge on the behaviour of the geomagnetic field through time critically depends on how information of the past state of the field is recorded by, and stored in iron-bearing minerals such as magnetite. For small, single domain grains these processes are described by classical Néel theory, but the magnetic behaviour of larger, pseudo-single domain or multidomain grains, still is enigmatic. Here we present a chemical, crystallographic and magnetic characterisation of three to six individual, large (~3–10 μm) iron-oxide grains from eleven different flows sampled on the Big Island of Hawai’i. These grains were all subjected to a Magnetic Force Microscopy study to characterise their magnetic domain structure; a Microprobe analyses to assess their chemical composition; and a Scanning Electron Microscopy study to identify phases and crystallographic orientations. This comprehensive dataset enables systematic analyses of their magnetic behaviour as function of chemistry and forms the basis for future micromagnetic modelling studies eventually contributing to the development of a fundamental theory of magnetic behaviour in large iron-oxide grains.
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Affiliation(s)
- Geertje W Ter Maat
- Paleomagnetic laboratory Fort Hoofddijk, department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, the Netherlands.,Department of Geoscience and Petroleum, NTNU, 7491 Trondheim, Norway
| | - Gillian M Pennock
- Structural geology, department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, the Netherlands
| | - Lennart V de Groot
- Paleomagnetic laboratory Fort Hoofddijk, department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, the Netherlands
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Ó Conbhuí P, Williams W, Fabian K, Ridley P, Nagy L, Muxworthy AR. MERRILL: Micromagnetic Earth Related Robust Interpreted Language Laboratory. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS : G(3) 2018; 19:1080-1106. [PMID: 29937699 PMCID: PMC6001588 DOI: 10.1002/2017gc007279] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/03/2018] [Indexed: 06/08/2023]
Abstract
Complex magnetic domain structures and the energy barriers between them are responsible for pseudo-single-domain phenomena in rock magnetism and contribute significantly to the magnetic remanence of paleomagnetic samples. This article introduces MERRILL, an open source software package for three-dimensional micromagnetics optimized and designed for the calculation of such complex structures. MERRILL has a simple scripting user interface that requires little computational knowledge to use but provides research strength algorithms to model complex, inhomogeneous domain structures in magnetic materials. It uses a finite element/boundary element numerical method, optimally suited for calculating magnetization structures of local energy minima (LEM) in irregular grain geometries that are of interest to the rock and paleomagnetic community. MERRILL is able to simulate the magnetic characteristics of LEM states in both single grains, and small assemblies of interacting grains, including saddle-point paths between nearby LEMs. Here the numerical model is briefly described, and an overview of the scripting language and available commands is provided. The open source nature of the code encourages future development of the model by the scientific community.
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Affiliation(s)
| | - Wyn Williams
- School of GeoSciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Karl Fabian
- Geological Survey of NorwayTrondheimNorway
- Department of GeologyUniversity of TromsøTromsøNorway
| | - Phil Ridley
- Cray UK Ltd, Broad Quay House, Broad QuayBristolUnited Kingdom
| | - Lesleis Nagy
- School of GeoSciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Adrian R. Muxworthy
- Natural Magnetism Group, Department of Earth Science and EngineeringImperial College LondonLondonUnited Kingdom
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7
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Almeida TP, Temple R, Massey J, Fallon K, McGrouther D, Moore T, Marrows CH, McVitie S. Quantitative TEM imaging of the magnetostructural and phase transitions in FeRh thin film systems. Sci Rep 2017; 7:17835. [PMID: 29259255 PMCID: PMC5736605 DOI: 10.1038/s41598-017-18194-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/07/2017] [Indexed: 11/26/2022] Open
Abstract
Equi-atomic FeRh is a very interesting material as it undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase between 75-105 °C. Its ability to present phase co-existence separated by domain walls (DWs) above room temperature provides immense potential for exploitation of their DW motion in spintronic devices. To be able to effectively control the DWs associated with AF/FM coexistence in FeRh thin films we must fully understand the magnetostructural transition and thermomagnetic behaviour of DWs at a localised scale. Here we present a transmission electron microscopy investigation of the transition in planar FeRh thin-film samples by combining differential phase contrast (DPC) magnetic imaging with in situ heating. We perform quantitative measurements from individual DWs as a function of temperature, showing that FeRh on NiAl exhibits thermomagnetic behaviour consistent with the transition from AF to FM. DPC imaging of an FeRh sample with HF-etched substrate reveals a state of AF/FM co-existence and shows the transition from AF to FM regions proceeds via nucleation of small vortex structures, which then grow by combining with newly nucleated vortex states into larger complex magnetic domains, until it is in a fully-FM state.
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Affiliation(s)
- Trevor P Almeida
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Rowan Temple
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Jamie Massey
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Kayla Fallon
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Thomas Moore
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | | | - Stephen McVitie
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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Stability of equidimensional pseudo-single-domain magnetite over billion-year timescales. Proc Natl Acad Sci U S A 2017; 114:10356-10360. [PMID: 28874562 DOI: 10.1073/pnas.1708344114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interpretations of paleomagnetic observations assume that naturally occurring magnetic particles can retain their primary magnetic recording over billions of years. The ability to retain a magnetic recording is inferred from laboratory measurements, where heating causes demagnetization on the order of seconds. The theoretical basis for this inference comes from previous models that assume only the existence of small, uniformly magnetized particles, whereas the carriers of paleomagnetic signals in rocks are usually larger, nonuniformly magnetized particles, for which there is no empirically complete, thermally activated model. This study has developed a thermally activated numerical micromagnetic model that can quantitatively determine the energy barriers between stable states in nonuniform magnetic particles on geological timescales. We examine in detail the thermal stability characteristics of equidimensional cuboctahedral magnetite and find that, contrary to previously published theories, such nonuniformly magnetized particles provide greater magnetic stability than their uniformly magnetized counterparts. Hence, nonuniformly magnetized grains, which are commonly the main remanence carrier in meteorites and rocks, can record and retain high-fidelity magnetic recordings over billions of years.
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