1
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Patel AK, Samatham SS, Lukoyanov AV, Babu PD, Suresh KG. Nearly compensated ferrimagnetic behaviour and giant exchange bias of hexagonal Mn 2PtAl: experimental and theoretical studies. Phys Chem Chem Phys 2022; 24:29539-29546. [PMID: 36448471 DOI: 10.1039/d2cp02643k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have investigated the Mn2PtAl Heulser alloy to unravel its structural, magnetic, calorimetric and electronic structure properties. At room temperature, the alloy crystallizes in a hexagonal structure. Magnetization reveals a weak martensitic transition at 307 K, followed by a long range ferrimagnetic transition at 90 K. Griffiths phase-like signature and positive Weiss temperature in dc-magnetization, isothermal magnetic hysteresis loops and a frequency-independent peak confirm a nearly compensated ferrimagnetic order of Mn2PtAl. The theoretical electronic structure calculations also reveal the ferrimagnetic ground state of Mn2PtAl and Mn ions (occupying different sites) with a very small total magnetic moment. A giant exchange bias field of 2.73 kOe, at a temperature of 3 K and a cooling field of 70 kOe, has been estimated and is attributed to the unidirectional anisotropy associated with possible ferromagnetic clusters formed by the field cooling process in the ferrimagnetic matrix.
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Affiliation(s)
- Akhilesh Kumar Patel
- Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India.,Department of Materials Science and Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - S Shanmukharao Samatham
- Department of Physics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad 500 075, India.
| | - Alexey V Lukoyanov
- M. N. Mikheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620108 Ekaterinburg, Russia.,Ural Federal University, 620002, Ekaterinburg, Russia
| | - P D Babu
- UGC-DAE Consortium for Scientific Research, Mumbai Center, BARC Campus, Mumbai 400085, India
| | - K G Suresh
- Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
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2
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Chatterjee S, Giri S, Majumdar S, Dutta P, Singha P, Banerjee A. Observation of Griffiths-like phase in the quaternary Heusler compound NiFeTiSn. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:295803. [PMID: 35533668 DOI: 10.1088/1361-648x/ac6e1f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/09/2022] [Indexed: 06/14/2023]
Abstract
The quaternary Heusler compound NiFeTiSn can be considered to be derived from the exotic pseudogap-compound Fe2TiSn by the replacement of one Fe atom by Ni. In contrast to Fe2TiSn, which shows a disorder induced ferromagnetic phase, the ground state of NiFeTiSn is antiferromagnetic with the signature of spin canting. Interestingly, NiFeTiSn shows a Griffiths-like phase characterized by isolated ferromagnetic clusters before attaining the antiferromagnetic state. The Griffiths-like phase is possibly associated with the antisite disorder between Fe and Ti sites as evident from our powder x-ray diffraction study. The compound also shows rather unusual temperature dependence of resistivity, which can be accounted by the prevailing structural disorder in the system. NiFeTiSn turned out to be a rare example where Griffiths-like phase is observed in a semiconducting 3dtransition metal based intermetallic compound with antiferromagnetic ground state.
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Affiliation(s)
- Snehashish Chatterjee
- School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Saurav Giri
- School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Subham Majumdar
- School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Prabir Dutta
- Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Pintu Singha
- Department of Physics, University of Calcutta, Kolkata 700009, India
| | - Aritra Banerjee
- Department of Physics, University of Calcutta, Kolkata 700009, India
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3
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dos Reis RD, Caron L, Singh S, Felser C, Nicklas M. Direct and Indirect Determination of the Magnetocaloric Effect in the Heusler Compound Ni 1.7Pt 0.3MnGa. ENTROPY 2021; 23:e23101273. [PMID: 34681997 PMCID: PMC8534797 DOI: 10.3390/e23101273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 11/16/2022]
Abstract
Magnetic shape-memory materials are potential magnetic refrigerants, due the caloric properties of their magnetic-field-induced martensitic transformation. The first-order nature of the martensitic transition may be the origin of hysteresis effects that can hinder practical applications. Moreover, the presence of latent heat in these transitions requires direct methods to measure the entropy and to correctly analyze the magnetocaloric effect. Here, we investigated the magnetocaloric effect in the Heusler material Ni1.7Pt0.3MnGa by combining an indirect approach to determine the entropy change from isofield magnetization curves and direct heat-flow measurements using a Peltier calorimeter. Our results demonstrate that the magnetic entropy change ΔS in the vicinity of the first-order martensitic phase transition depends on the measuring method and is directly connected with the temperature and field history of the experimental processes.
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Affiliation(s)
- Ricardo D. dos Reis
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany; (L.C.); (S.S.); (C.F.); (M.N.)
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas 13083-970, Brazil
- Correspondence:
| | - Luana Caron
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany; (L.C.); (S.S.); (C.F.); (M.N.)
- Faculty of Physics, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Sanjay Singh
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany; (L.C.); (S.S.); (C.F.); (M.N.)
- School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi 221005, India
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany; (L.C.); (S.S.); (C.F.); (M.N.)
| | - Michael Nicklas
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany; (L.C.); (S.S.); (C.F.); (M.N.)
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4
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Sharma AK, Jena J, Rana KG, Markou A, Meyerheim HL, Mohseni K, Srivastava AK, Kostanoskiy I, Felser C, Parkin SSP. Nanoscale Noncollinear Spin Textures in Thin Films of a D 2d Heusler Compound. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101323. [PMID: 34218470 DOI: 10.1002/adma.202101323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 06/13/2023]
Abstract
Magnetic nano-objects, namely antiskyrmions and Bloch skyrmions, have been found to coexist in single-crystalline lamellae formed from bulk crystals of inverse tetragonal Heusler compounds with D2d symmetry. Here evidence is shown for magnetic nano-objects in epitaxial thin films of Mn2 RhSn formed by magnetron sputtering. These nano-objects exhibit a wide range of sizes with stability with respect to magnetic field and temperature that is similar to single-crystalline lamellae. However, the nano-objects do not form well-defined arrays, nor is any evidence found for helical spin textures. This is speculated to likely be a consequence of the poorer homogeneity of chemical ordering in the thin films. However, evidence is found for elliptically distorted nano-objects along perpendicular crystallographic directions within the epitaxial films, which is consistent with elliptical Bloch skyrmions observed in single-crystalline lamellae. Thus, these measurements provide strong evidence for the formation of noncollinear spin textures in thin films of Mn2 RhSn. Using these films, it is shown that individual nano-objects can be deleted using a local magnetic field from a magnetic tip and collections of nano-objects can be similarly written. These observations suggest a path toward the use of these objects in thin films with D2d symmetry as magnetic memory elements.
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Affiliation(s)
- Ankit K Sharma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Kumari Gaurav Rana
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Anastasios Markou
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Holger L Meyerheim
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Katayoon Mohseni
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Abhay K Srivastava
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Ilya Kostanoskiy
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
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5
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Wei Q, Wang H, Ma J, Zhao X, Zhao J. Magneto-transport properties of cubic NiMnAs film epitaxied on GaAs (110) substrate. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:315702. [PMID: 34020432 DOI: 10.1088/1361-648x/ac03d4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/21/2021] [Indexed: 06/12/2023]
Abstract
The magneto-transport properties of cubic NiMnAs film epitaxied on the GaAs (110) substrate are investigated. The x-ray diffraction measurements reveal that the NiMnAs (111) crystal plane is parallel to the GaAs (110) crystal plane. The temperature dependence of resistivity at high temperature can be described by a thermal activation model, from which the thermal activation energy is obtained and found to be comparable with many other Heusler alloys. By fitting the temperature dependence of resistivity at low temperature, the coefficient of the quadratic temperature term is determined to be 1.34 × 10-3μΩ cm K-2. This value suggests the possible presence of single-magnon scattering in the NiMnAs film. The negative magnetoresistance is attributed to the suppression of the spin-dependent scattering, which would not take place in a half-metal. The angle dependence of the anisotropic magnetoresistance (AMR) is measured, and the AMR ratios are positive even at low temperature. These magneto-transport properties indicate that the predicted half-metallicity is destroyed in the NiMnAs film. The absence of the half-metallicity may be attributed to the atomic disorder in the NiMnAs lattice, which needs to be confirmed by further experimental and theoretical studies.
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Affiliation(s)
- Qiqi Wei
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jialin Ma
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Xupeng Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
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6
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Jena J, Göbel B, Kumar V, Mertig I, Felser C, Parkin S. Evolution and competition between chiral spin textures in nanostripes with D 2d symmetry. SCIENCE ADVANCES 2020; 6:6/49/eabc0723. [PMID: 33277247 PMCID: PMC7821896 DOI: 10.1126/sciadv.abc0723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Chiral spin textures are of considerable interest for applications in spintronics. It has recently been shown that magnetic materials with D 2d symmetry can sustain several distinct spin textures. Here, we show, using Lorentz transmission electron microscopy, that single and double chains of antiskyrmions can be generated at room temperature in nanostripes less than 0.5 μm in width formed from the D 2d Heusler compound Mn1.4Pt0.9Pd0.1Sn. Typically, truncated helical spin textures are formed in low magnetic fields, whose edges are terminated by half antiskyrmions. These evolve into chains of antiskyrmions with increasing magnetic field. Single chains of these objects are located in the middle of the nanostripes even when the stripes are much wider than the antiskyrmions. Moreover, the chains can even include elliptical Bloch skyrmions depending on details of the applied magnetic field history. These findings make D 2d materials special and highly interesting for applications such as magnetic racetrack memory storage devices.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Stuart Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
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7
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He Y, Fecher GH, Fu C, Pan Y, Manna K, Kroder J, Jha A, Wang X, Hu Z, Agrestini S, Herrero-Martín J, Valvidares M, Skourski Y, Schnelle W, Stamenov P, Borrmann H, Tjeng LH, Schaefer R, Parkin SSP, Coey JMD, Felser C. A New Highly Anisotropic Rh-Based Heusler Compound for Magnetic Recording. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004331. [PMID: 33029834 DOI: 10.1002/adma.202004331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/02/2020] [Indexed: 06/11/2023]
Abstract
The development of high-density magnetic recording media is limited by superparamagnetism in very small ferromagnetic crystals. Hard magnetic materials with strong perpendicular anisotropy offer stability and high recording density. To overcome the difficulty of writing media with a large coercivity, heat-assisted magnetic recording was developed, rapidly heating the media to the Curie temperature Tc before writing, followed by rapid cooling. Requirements are a suitable Tc , coupled with anisotropic thermal conductivity and hard magnetic properties. Here, Rh2 CoSb is introduced as a new hard magnet with potential for thin-film magnetic recording. A magnetocrystalline anisotropy of 3.6 MJ m-3 is combined with a saturation magnetization of μ0 Ms = 0.52 T at 2 K (2.2 MJ m-3 and 0.44 T at room temperature). The magnetic hardness parameter of 3.7 at room temperature is the highest observed for any rare-earth-free hard magnet. The anisotropy is related to an unquenched orbital moment of 0.42 μB on Co, which is hybridized with neighboring Rh atoms with a large spin-orbit interaction. Moreover, the pronounced temperature dependence of the anisotropy that follows from its Tc of 450 K, together with a thermal conductivity of 20 W m-1 K-1 , make Rh2 CoSb a candidate for the development of heat-assisted writing with a recording density in excess of 10 Tb in.-2 .
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Affiliation(s)
- Yangkun He
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Gerhard H Fecher
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Chenguang Fu
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Yu Pan
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Kaustuv Manna
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Johannes Kroder
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Ajay Jha
- School of Physics, Trinity College, Dublin 2, Ireland
| | - Xiao Wang
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Zhiwei Hu
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Stefano Agrestini
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Javier Herrero-Martín
- ALBA Synchrotron Light Source, Cerdanyola del Valles, Barcelona, Catalonia, 08290, Spain
| | - Manuel Valvidares
- ALBA Synchrotron Light Source, Cerdanyola del Valles, Barcelona, Catalonia, 08290, Spain
| | - Yurii Skourski
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-zentrum Dresden-Rossendorf, Dresden, 01328, Germany
| | - Walter Schnelle
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | | | - Horst Borrmann
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Liu Hao Tjeng
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
| | - Rudolf Schaefer
- Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtz strasse 20, Dresden, D-01069, Germany
- Institute for Materials Science, TU Dresden, Dresden, D-01062, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Halle, 06120, Germany
| | | | - Claudia Felser
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187, Germany
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8
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Sivakumar P, Göbel B, Lesne E, Markou A, Gidugu J, Taylor JM, Deniz H, Jena J, Felser C, Mertig I, Parkin SSP. Topological Hall Signatures of Two Chiral Spin Textures Hosted in a Single Tetragonal Inverse Heusler Thin Film. ACS NANO 2020; 14:13463-13469. [PMID: 32986403 PMCID: PMC7596786 DOI: 10.1021/acsnano.0c05413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/28/2020] [Indexed: 06/11/2023]
Abstract
Magnetic skyrmions and antiskyrmions are observed in material classes with different crystal symmetries, where the Dzyaloshinskii-Moriya interaction stabilizes either skyrmions or antiskyrmions. Here, we report the observation of two distinct peaks in the topological Hall effect in a thin film of Mn2RhSn. Utilizing a phenomenological approach and electronic transport simulations, these topological Hall effect features are attributed to be direct signatures of two topologically distinct chiral spin objects, namely, skyrmions and antiskyrmions. Topological Hall effect studies allow us to determine the existence of these two topological objects over a wide range of temperature and magnetic fields. In particular, we find skyrmions to be stable at low temperatures, suggesting the increased importance of dipolar interactions.
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Affiliation(s)
- Pranava
K. Sivakumar
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Börge Göbel
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institute
of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Edouard Lesne
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Anastasios Markou
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Jyotsna Gidugu
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - James M. Taylor
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Hakan Deniz
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Jagannath Jena
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Claudia Felser
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Ingrid Mertig
- Institute
of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Stuart S. P. Parkin
- Max
Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
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9
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Seyd J, Pilottek I, Schmidt NY, Caha O, Urbánek M, Albrecht M. Mn 3Ge-based tetragonal Heusler alloy thin films with addition of Ni, Pt, and Pd. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:145801. [PMID: 31791025 DOI: 10.1088/1361-648x/ab5e16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have investigated substitution effects of Ni, Pt, and Pd on phase formation and magnetic properties of D022-Mn3Ge thin films. We prepared (Mn1-x M x )3Ge thin films (M = Ni, Pt, Pd) at 650 °C by magnetron sputtering on MgO(0 0 1) substrates with x varying from 0.03 to 0.6. For improving the film quality, a Cr(0 0 1) seed layer was employed. The D022 structure formed only for the lowest concentrations of Ni and Pt. Nevertheless, the doped samples showed strong perpendicular magnetic anisotropy up to x = 0.1. For high Ni concentrations, we observed the formation of a soft ferromagnetic Mn x Ni y Ge phase with a Curie temperature of about 230 K, while in samples with high Pt content the antiferromagnet L10-MnPt phase is formed along with GePt. In contrast, for Pd substitution, the D022 structure is preserved up to x = 0.2, exhibiting strong perpendicular magnetic anisotropy and low saturation magnetization. Interestingly, the coexistence of the D022-Mn3Ge and a novel D022-(Mn1-x Pd x )3Ge phase was revealed, which might have been facilitated by the low lattice mismatch to the Cr(0 0 1) seed layer. With further increase of the Pd concentration, the D022 structure vanishes and mainly the GePd and GePd2 phases are present. Overall within the investigated sample series, the saturation magnetization strongly decreases with increasing dopant concentration, offering the possibility to adjust the saturation magnetization in the range between 20 and 100 emu cm-3, while still preserving strong perpendicular magnetic anisotropy, which is important for spintronic applications.
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Affiliation(s)
- J Seyd
- Institute of Physics, University of Augsburg, D-86159 Augsburg, Germany
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10
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Jena J, Göbel B, Ma T, Kumar V, Saha R, Mertig I, Felser C, Parkin SSP. Elliptical Bloch skyrmion chiral twins in an antiskyrmion system. Nat Commun 2020; 11:1115. [PMID: 32111842 PMCID: PMC7048809 DOI: 10.1038/s41467-020-14925-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 02/12/2020] [Indexed: 11/22/2022] Open
Abstract
Skyrmions and antiskyrmions are distinct topological chiral spin textures that have been observed in various material systems depending on the symmetry of the crystal structure. Here we show, using Lorentz transmission electron microscopy, that arrays of skyrmions can be stabilized in a tetragonal inverse Heusler with D2d symmetry whose Dzyaloshinskii-Moriya interaction (DMI) otherwise supports antiskyrmions. These skyrmions can be distinguished from those previously found in several B20 systems which have only one chirality and are circular in shape. We find Bloch-type elliptical skyrmions with opposite chiralities whose major axis is oriented along two specific crystal directions: [010] and [100]. These structures are metastable over a wide temperature range and we show that they are stabilized by long-range dipole-dipole interactions. The possibility of forming two distinct chiral spin textures with opposite topological charges of ±1 in one material makes the family of D2d materials exceptional. Skyrmions and anti-skyrmions often exist in distinct material systems. Here, the authors observe elliptical skyrmions and anti-skyrmions with opposite topological charges in one tetragonal Heusler compound Mn1.4Pt0.9Pd0.1Sn with D2d symmetry.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Tianping Ma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Rana Saha
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Ingrid Mertig
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.
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11
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Jena J, Stinshoff R, Saha R, Srivastava AK, Ma T, Deniz H, Werner P, Felser C, Parkin SSP. Observation of Magnetic Antiskyrmions in the Low Magnetization Ferrimagnet Mn 2Rh 0.95Ir 0.05Sn. NANO LETTERS 2020; 20:59-65. [PMID: 31809059 PMCID: PMC6953472 DOI: 10.1021/acs.nanolett.9b02973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Recently, magnetic antiskyrmions were discovered in Mn1.4Pt0.9Pd0.1Sn, an inverse tetragonal Heusler compound that is nominally a ferrimagnet, but which can only be formed with substantial Mn vacancies. The vacancies reduce considerably the compensation of the moments between the two expected antiferromagnetically coupled Mn sub-lattices so that the overall magnetization is very high and the compound is almost a "ferromagnet". Here, we report the observation of antiskyrmions in a second inverse tetragonal Heusler compound, Mn2Rh0.95Ir0.05Sn, which can be formed stoichiometrically without any Mn vacancies and which thus exhibits a much smaller magnetization. Individual and lattices of antiskyrmions can be stabilized over a wide range of temperature from near room temperature to 100 K, the base temperature of the Lorentz transmission electron microscope used to image them. In low magnetic fields helical spin textures are found which evolve into antiskyrmion structures in the presence of small magnetic fields. A weaker Dzyaloshinskii-Moriya interaction (DMI), that stabilizes the antiskyrmions, is expected for the 4d element Rh as compared to the 5d element Pt, so that the observation of antiskyrmions in Mn2Rh0.95Ir0.05Sn establishes the intrinsic stability of antiskyrmions in these Heusler compounds. Moreover, the finding of antiskyrmions with substantially lower magnetization promises, via chemical tuning, even zero moment antiskyrmions with important technological import.
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Affiliation(s)
- Jagannath Jena
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Rolf Stinshoff
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Rana Saha
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Abhay K. Srivastava
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
- Institute
of Physics, Martin Luther University, Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Tianping Ma
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hakan Deniz
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Peter Werner
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Claudia Felser
- Max
Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Stuart S. P. Parkin
- Max Planck
Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
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12
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Vir P, Kumar N, Borrmann H, Jamijansuren B, Kreiner G, Shekhar C, Felser C. Tetragonal Superstructure of the Antiskyrmion Hosting Heusler Compound Mn 1.4PtSn. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2019; 31:5876-5880. [PMID: 31423051 PMCID: PMC6694724 DOI: 10.1021/acs.chemmater.9b02013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/10/2019] [Indexed: 05/30/2023]
Abstract
Skyrmions in non-centrosymmetric magnets are vortex-like spin arrangements, viewed as potential candidates for information storage devices. The crystal structure and noncollinear magnetic structure together with magnetic and spin-orbit interactions define the symmetry of the skyrmion structure. We outline the importance of these parameters in the Heusler compound Mn1.4PtSn which hosts antiskyrmions, a vortex-like spin texture related to skyrmions. We overcome the challenge of growing large micro-twin-free single crystals of Mn1.4PtSn, which has proved to be the bottleneck for realizing bulk skyrmionic/antiskyrmionic states in a compound. The use of 5d-transition metal, platinum, together with manganese as constituents in the Heusler compound such as Mn1.4PtSn is a precondition for the noncollinear magnetic structure. Because of the tetragonal inverse Heusler structure, Mn1.4PtSn exhibits large magneto-crystalline anisotropy and D 2d symmetry, which are necessary for antiskyrmions. The superstructure in Mn1.4PtSn is induced by Mn-vacancies, which enable a ferromagnetic exchange interaction to occur. Mn1.4PtSn, the first known tetragonal Heusler superstructure compound, opens up a new research direction for properties related to the superstructure in a family containing thousands of compounds.
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13
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Schlitz R, Swekis P, Markou A, Reichlova H, Lammel M, Gayles J, Thomas A, Nielsch K, Felser C, Goennenwein STB. All Electrical Access to Topological Transport Features in Mn 1.8PtSn Films. NANO LETTERS 2019; 19:2366-2370. [PMID: 30844284 DOI: 10.1021/acs.nanolett.8b05042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The presence of nontrivial magnetic topology can give rise to nonvanishing scalar spin chirality and consequently a topological Hall or Nernst effect. In turn, topological transport signals can serve as indicators for topological spin structures. This is particularly important in thin films or nanopatterned materials where the spin structure is not readily accessible. Conventionally, the topological response is determined by combining magnetotransport data with an independent magnetometry experiment. This approach is prone to introduce measurement artifacts. In this study, we report the observation of large topological Hall and Nernst effects in micropatterned thin films of Mn1.8PtSn below the spin reorientation temperature TSR ≈ 190 K. The magnitude of the topological Hall effect ρ xyT = 8 nΩm is close to the value reported in bulk Mn2PtSn, and the topological Nernst effect S xyT = 115 nV K-1 measured in the same microstructure has a similar magnitude as reported for bulk MnGe ( S xyT ∼ 150 nV K-1), the only other material where a topological Nernst was reported. We use our data as a model system to introduce a topological quantity, which allows one to detect the presence of topological transport effects without the need for independent magnetometry data. Our approach thus enables the study of topological transport also in nanopatterned materials without detrimental magnetization related limitations.
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Affiliation(s)
- Richard Schlitz
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
| | - Peter Swekis
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Anastasios Markou
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Helena Reichlova
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute of Physics ASCR , v. v. i., Cukrovarnická 10 , 162 53 , Praha 6 , Czech Republic
| | - Michaela Lammel
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
| | - Jacob Gayles
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Andy Thomas
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
| | - Kornelius Nielsch
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
- Institute of Materials Science , Technische Universität Dresden , 01062 Dresden , Germany
| | - Claudia Felser
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Sebastian T B Goennenwein
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
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14
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Herran J, Prophet S, Jin Y, Valloppilly S, Kharel PR, Sellmyer DJ, Lukashev PV. Structural and magnetic properties of bulk Mn 2PtSn. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:475801. [PMID: 30378571 DOI: 10.1088/1361-648x/aae652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Interplay between structural and magnetic order parameters is one of the key mechanisms of tuning properties of materials intended for device applications in spintronics. Here, using density functional calculations, we study combined effects of tetragonal distortion and non-collinear magnetic order in Mn2PtSn. We show that this material has two energetically close energy minimums corresponding to tetragonal lattice. In one of these phases, Mn2PtSn exhibits ferrimagnetic order with nearly fully compensated total magnetic moment, while in the other phase that corresponds to the lowest energy, a non-collinear magnetic arrangement emerges, with very large canting angle of the Mn local magnetic moments. The non-collinear alignment is explained through the interplay of exchange couplings between nearest and next nearest neighbor Mn atoms. Results are compared with those reported in recent literature, both experimental and theoretical.
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Affiliation(s)
- J Herran
- Department of Chemistry and Biochemistry, University of Northern Iowa, Cedar Falls, IA 50614, United States of America
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15
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Chiral domain wall motion in unit-cell thick perpendicularly magnetized Heusler films prepared by chemical templating. Nat Commun 2018; 9:4653. [PMID: 30405099 PMCID: PMC6220290 DOI: 10.1038/s41467-018-07091-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 10/01/2018] [Indexed: 11/08/2022] Open
Abstract
Heusler alloys are a large family of compounds with complex and tunable magnetic properties, intimately connected to the atomic scale ordering of their constituent elements. We show that using a chemical templating technique of atomically ordered X'Z' (X' = Co; Z' = Al, Ga, Ge, Sn) underlayers, we can achieve near bulk-like magnetic properties in tetragonally distorted Heusler films, even at room temperature. Excellent perpendicular magnetic anisotropy is found in ferrimagnetic X3Z (X = Mn; Z = Ge, Sn, Sb) films, just 1 or 2 unit-cells thick. Racetracks formed from these films sustain current-induced domain wall motion with velocities of more than 120 m s-1, at current densities up to six times lower than conventional ferromagnetic materials. We find evidence for a significant bulk chiral Dzyaloshinskii-Moriya exchange interaction, whose field strength can be systematically tuned by an order of magnitude. Our work is an important step towards practical applications of Heusler compounds for spintronic technologies.
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16
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Magnetic antiskyrmions above room temperature in tetragonal Heusler materials. Nature 2017; 548:561-566. [DOI: 10.1038/nature23466] [Citation(s) in RCA: 400] [Impact Index Per Article: 57.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Accepted: 06/21/2017] [Indexed: 12/25/2022]
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17
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Hoffmann M, Zimmermann B, Müller GP, Schürhoff D, Kiselev NS, Melcher C, Blügel S. Antiskyrmions stabilized at interfaces by anisotropic Dzyaloshinskii-Moriya interactions. Nat Commun 2017; 8:308. [PMID: 28827700 PMCID: PMC5566362 DOI: 10.1038/s41467-017-00313-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 06/15/2017] [Indexed: 11/09/2022] Open
Abstract
Chiral magnets are an emerging class of topological matter harboring localized and topologically protected vortex-like magnetic textures called skyrmions, which are currently under intense scrutiny as an entity for information storage and processing. Here, on the level of micromagnetics we rigorously show that chiral magnets can not only host skyrmions but also antiskyrmions as least energy configurations over all non-trivial homotopy classes. We derive practical criteria for their occurrence and coexistence with skyrmions that can be fulfilled by (110)-oriented interfaces depending on the electronic structure. Relating the electronic structure to an atomistic spin-lattice model by means of density functional calculations and minimizing the energy on a mesoscopic scale by applying spin-relaxation methods, we propose a double layer of Fe grown on a W(110) substrate as a practical example. We conjecture that ultra-thin magnetic films grown on semiconductor or heavy metal substrates with C 2v symmetry are prototype classes of materials hosting magnetic antiskyrmions.Skyrmions, localized defects in the magnetization, can be stabilised in materials by the Dzyaloshinskii-Moriya interaction (DMI). Hoffmann et al. predict that, when the DMI is anisotropic, antiskyrmions can be formed and coexist with skyrmions, enabling studies and exploitation of their interactions.
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Affiliation(s)
- Markus Hoffmann
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany.
| | - Bernd Zimmermann
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Gideon P Müller
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
- Science Institute of the University of Iceland, VR-III, 107, Reykjavík, Iceland
| | - Daniel Schürhoff
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Nikolai S Kiselev
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Christof Melcher
- Department of Mathematics I & JARA FIT, RWTH Aachen University, 52056, Aachen, Germany
| | - Stefan Blügel
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
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18
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Kundu A, Ghosh S, Banerjee R, Ghosh S, Sanyal B. New quaternary half-metallic ferromagnets with large Curie temperatures. Sci Rep 2017; 7:1803. [PMID: 28496114 PMCID: PMC5431771 DOI: 10.1038/s41598-017-01782-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/04/2017] [Indexed: 12/03/2022] Open
Abstract
New magnetic materials with high Curie temperatures for spintronic applications are perpetually sought for. In this paper, we present an ab initio study of the structural, electronic and magnetic properties of Quaternary Heusler compounds CoX′Y′Si where X′ is a transition metal with 4d electrons and Y′ is either Fe or Mn. We find five new half-metallic ferromagnets with spin polarisation nearly 100% with very high Curie temperatures. The variation of Curie temperatures as a function of valence electrons can be understood from the calculated inter-atomic exchange interaction parameters. We also identify a few other compounds, which could be potential half-metals with suitable application of pressure or with controlled doping. Our results reveal that the half-metallicity in these compounds is intricately related to the arrangements of the magnetic atoms in the Heusler lattice and hence, the interatomic exchange interactions between the moments. The trends in the atomic arrangements, total and local magnetic moments, interatomic magnetic exchange interactions and Curie temperatures are discussed with fundamental insights.
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Affiliation(s)
- Ashis Kundu
- Department of Physics, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Srikrishna Ghosh
- Department of Physics, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Rudra Banerjee
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
| | - Subhradip Ghosh
- Department of Physics, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Biplab Sanyal
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden.
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19
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Sanvito S, Oses C, Xue J, Tiwari A, Zic M, Archer T, Tozman P, Venkatesan M, Coey M, Curtarolo S. Accelerated discovery of new magnets in the Heusler alloy family. SCIENCE ADVANCES 2017; 3:e1602241. [PMID: 28439545 PMCID: PMC5392031 DOI: 10.1126/sciadv.1602241] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 02/14/2017] [Indexed: 05/10/2023]
Abstract
Magnetic materials underpin modern technologies, ranging from data storage to energy conversion to contactless sensing. However, the development of a new high-performance magnet is a long and often unpredictable process, and only about two dozen magnets are featured in mainstream applications. We describe a systematic pathway to the design of novel magnetic materials, which demonstrates a high throughput and discovery speed. On the basis of an extensive electronic structure library of Heusler alloys containing 236,115 prototypical compounds, we filtered those displaying magnetic order and established whether they can be fabricated at thermodynamic equilibrium. Specifically, we carried out a full stability analysis of intermetallic Heusler alloys made only of transition metals. Among the possible 36,540 prototypes, 248 were thermodynamically stable but only 20 were magnetic. The magnetic ordering temperature, TC, was estimated by a regression calibrated on the experimental TC of about 60 known compounds. As a final validation, we attempted the synthesis of a few of the predicted compounds and produced two new magnets: Co2MnTi, which displays a remarkably high TC in perfect agreement with the predictions, and Mn2PtPd, which is an antiferromagnet. Our work paves the way for large-scale design of novel magnetic materials at potentially high speed.
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Affiliation(s)
- Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
- Center for Materials Genomics, Duke University, Durham, NC 27708, USA
| | - Corey Oses
- Center for Materials Genomics, Duke University, Durham, NC 27708, USA
- Departments of Mechanical Engineering and Materials Science, Physics, and Chemistry, Duke University, Durham, NC 27708, USA
| | - Junkai Xue
- Center for Materials Genomics, Duke University, Durham, NC 27708, USA
- Departments of Mechanical Engineering and Materials Science, Physics, and Chemistry, Duke University, Durham, NC 27708, USA
| | - Anurag Tiwari
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Mario Zic
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Thomas Archer
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Pelin Tozman
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Munuswamy Venkatesan
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Michael Coey
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Stefano Curtarolo
- Center for Materials Genomics, Duke University, Durham, NC 27708, USA
- Departments of Mechanical Engineering and Materials Science, Physics, and Chemistry, Duke University, Durham, NC 27708, USA
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20
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Sahoo R, Wollmann L, Selle S, Höche T, Ernst B, Kalache A, Shekhar C, Kumar N, Chadov S, Felser C, Parkin SSP, Nayak AK. Compensated Ferrimagnetic Tetragonal Heusler Thin Films for Antiferromagnetic Spintronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:8499-8504. [PMID: 27500768 DOI: 10.1002/adma.201602963] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 07/03/2016] [Indexed: 06/06/2023]
Abstract
Fully compensated ferrimagnets with tetragonal crystal structure have the potential for large spin-polarization and strong out-of-plane magnetic anisotropy; hence, they are ideal candidates for high-density-memory applications. Tetragonal Heusler thin films with compensated magnetic state are realized by substitution of Pt in Mn3-x Ptx Ga. Furthermore, the bilayer formed from compensated/uncompensated Mn-Pt-Ga layers is utilized to accomplish exchange bias up to room temperature.
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Affiliation(s)
- Roshnee Sahoo
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Lukas Wollmann
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Susanne Selle
- Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter-Hülse-Str. 1, 06120, Halle, Germany
| | - Thomas Höche
- Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter-Hülse-Str. 1, 06120, Halle, Germany
| | - Benedikt Ernst
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Adel Kalache
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Nitesh Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Stanislav Chadov
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Ajaya K Nayak
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany.
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany.
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21
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Singh S, D'Souza SW, Nayak J, Suard E, Chapon L, Senyshyn A, Petricek V, Skourski Y, Nicklas M, Felser C, Chadov S. Room-temperature tetragonal non-collinear Heusler antiferromagnet Pt2MnGa. Nat Commun 2016; 7:12671. [PMID: 27561795 PMCID: PMC5007462 DOI: 10.1038/ncomms12671] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/21/2016] [Indexed: 12/04/2022] Open
Abstract
Antiferromagnetic spintronics is a rapidly growing field, which actively introduces new principles of magnetic storage. Despite that, most applications have been suggested for collinear antiferromagnets. In this study, we consider an alternative mechanism based on long-range helical order, which allows for direct manipulation of the helicity vector. As the helicity of long-range homogeneous spirals is typically fixed by the Dzyaloshinskii-Moriya interactions, bi-stable spirals (left- and right-handed) are rare. Here, we report a non-collinear room-temperature antiferromagnet in the tetragonal Heusler group. Neutron diffraction reveals a long-period helix propagating along its tetragonal axis. Ab-initio analysis suggests its pure exchange origin and explains its helical character resulting from a large basal plane magnetocrystalline anisotropy. The actual energy barrier between the left- and right-handed spirals is relatively small and might be easily overcome by magnetic pulse, suggesting Pt2MnGa as a potential candidate for non-volatile magnetic memory.
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Affiliation(s)
- Sanjay Singh
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
| | - S. W. D'Souza
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
| | - J. Nayak
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
| | - E. Suard
- Institut Laue-Langevin, BP 156, Grenoble Cedex 9 38042, France
| | - L. Chapon
- Institut Laue-Langevin, BP 156, Grenoble Cedex 9 38042, France
| | - A. Senyshyn
- Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, Lichtenbergstrasse 1, Garching 85747, Germany
| | - V. Petricek
- Department of Structure Analysis, Institute of Physics ASCR, Na Slovance 2, Praha 18221, Czech Republic
| | - Y. Skourski
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, Dresden D-01328, Germany
| | - M. Nicklas
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
| | - C. Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
| | - S. Chadov
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden D-01187, Germany
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22
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Phatak C, Heinonen O, De Graef M, Petford-Long A. Nanoscale Skyrmions in a Nonchiral Metallic Multiferroic: Ni2MnGa. NANO LETTERS 2016; 16:4141-4148. [PMID: 27186990 DOI: 10.1021/acs.nanolett.6b01011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Magnetic skyrmions belong to a set of topologically nontrivial spin textures at the nanoscale that have received increased attention due to their emergent behavior and novel potential spintronic applications. Discovering materials systems that can host skyrmions at room temperature in the absence of external magnetic field is of crucial importance not only from a fundamental aspect, but also from a technological point of view. So far, the observations of skyrmions in bulk metallic ferromagnets have been limited to low temperatures and to materials that exhibit strong chiral interactions. Here we show the formation of nanoscale skyrmions in a nonchiral multiferroic material, which is ferromagnetic and ferroelastic, Ni2MnGa at room temperature without the presence of external magnetic fields. By using Lorentz transmission electron microscopy in combination with micromagnetic simulations, we elucidate their formation, behavior, and stability under applied magnetic fields at room temperature. The formation of skyrmions in a multiferroic material with no broken inversion symmetry presents new exciting opportunities for the exploration of the fundamental physics of topologically nontrivial spin textures.
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Affiliation(s)
- Charudatta Phatak
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
| | - Olle Heinonen
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
| | - Marc De Graef
- Department of Materials Science and Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Amanda Petford-Long
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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