Unusual magnetic properties of the atomically laminated Mn2GaC MAX phase
Iuliia Novoselova, University Duisburg-Essen, Duisburg, GermanyAndrejs Petruhins, Linköping University, Linköping, SwedenUlf Wiedwald, University Duisburg-Essen, Duisburg, GermanyÁrni Sigurdur Ingason, Linköping University, Linköping, SwedenThomas Hase, University of Warwick, Coventry, United KingdomFridrik Magnus, University of Iceland, Reykjavik, IcelandVassilios Kapaklis, Uppsala University, Uppsala, SwedenJustinas Palisaitis , Linköping University, Linköping, SwedenMarina Spasova, University Duisburg-Essen, Duisburg, GermanyMichael Farle, University Duisburg-Essen, Duisburg, GermanyJohanna Rosen, Linköping University, Linköping, SwedenRuslan Salikhov, University Duisburg-Essen, Duisburg, Germany
MAX phases (Mn+1AXn, n = 1-3) are inherently nanolaminated hexagonal compounds, composed of early transition metals M, A-group elements and X (C or N). They possess unique anisotropic structural and physical properties showing ceramic as well as metallic response, such as thermal shock tolerance, oxidation resistance, and good electrical and thermal conductivity . The magnetic ternary MAX phase, Mn2GaC, has been synthesized as a hetero-epitaxial film by magnetron sputtering .
Here, a comprehensive study of the temperature and field dependent magnetization, magnetoresistive (MR) and magnetostrictive (MS) properties is presented. The system exhibits two non-collinear antiferromagnetic states with a spin-reorientation transition occurring at Tt = 214 K and a high Neel temperature of TN = 507 K, where the system experiences a transition into a magnetically disordered state . Among the yet discovered MAX phases, Mn2GaC has the largest reported magnetic ordering temperature. A large uniaxial MS of 450 ppm at Tt in 2 Tesla was observed. The MS undergoes a sign change across the transition, being compressive (negative) above Tt and tensile (positive) below Tt. It is accompanied by a highly asymmetric MR of up to 3% in a magnetic field of 9 T at room temperature. The fact of simultaneous sign change of MS and MR indicates a strong coupling between the spin and lattice degrees of freedom. These magnetic properties open a pathway to new functionalities for practical applications.
This work is supported by DFG Grant SA 3095/2-1, DAAD Doctoral Programmes in Germany 2017/18 (57214224), Swedish Research Council (642-2013-8020) and the Swedish Foundation for Strategic Research (SSF) through the Synergy Grant FUNCASE.
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