Abstract
Multiple recent studies have identified the metallic antiferromagnet Mn2Au to be a candidate for spintronic applications due to apparent in-plane anisotropy, preserved magnetic properties above room temperature, and current-induced Néel vector switching. Crystal growth is complicated by the fact that Mn2Au melts incongruently. We present a bismuth flux method to grow millimeter-scale bulk single crystals of Mn2Au in order to examine the intrinsic anisotropic electrical and magnetic properties. Flux quenching experiments reveal that the Mn2Au crystals precipitate below 550∘C, about 100∘C below the decomposition temperature of Mn2Au. Bulk Mn2Au crystals have a room-temperature resistivity of 16-19 μωcm and a residual resistivity ratio of 41. Mn2Au crystals have a dimensionless susceptibility on the order of 10-4 (SI units), comparable to calculated and experimental reports on powder samples. Single-crystal neutron diffraction confirms the in-plane magnetic structure. The tetragonal symmetry of Mn2Au constrains the ab-plane magnetic susceptibility to be constant, meaning that χ100=χ110 in the low-field limit, below any spin-flop transition. We find that three measured magnetic susceptibilities χ100, χ110, and χ001 are the same order of magnitude and agree with the calculated prediction, meaning the low-field susceptibility of Mn2Au is quite isotropic, despite clear differences in ab-plane and ac-plane magnetocrystalline anisotropy. Mn2Au is calculated to have an extremely high in-plane spin-flop field above 30 T, which is much larger than that of another in-plane antiferromagnet, Fe2As (less than 1 T). The subtle anisotropy of intrinsic susceptibilities may lead to dominating effects from shape, crystalline texture, strain, and defects in devices that attempt spin readout in Mn2Au.
| Original language | English |
|---|---|
| Article number | 084413 |
| Journal | Physical Review Materials |
| Volume | 8 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 2024 |
Funding
This work was undertaken as part of the Illinois Materials Research Science and Engineering Center, supported by the National Science Foundation MRSEC program under NSF Award No. DMR-1720633. The characterization was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois. Single-crystal neutron diffraction was conducted at ORNL's High Flux Isotope Reactor, sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. This work made use of the Illinois Campus Cluster, a computing resource that is operated by the Illinois Campus Cluster Program (ICCP) in conjunction with the National Center for Supercomputing Applications (NCSA) and which is supported by funds from the University of Illinois at Urbana-Champaign. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (Awards No. OCI-0725070 and No. ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications. ACKNOWLEDGMENTS This work was undertaken as part of the Illinois Materials Research Science and Engineering Center, supported by the National Science Foundation MRSEC program under NSF Award No. DMR-1720633. The characterization was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois. Single-crystal neutron diffraction was conducted at ORNL's High Flux Isotope Reactor, sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. This work made use of the Illinois Campus Cluster, a computing resource that is operated by the Illinois Campus Cluster Program (ICCP) in conjunction with the National Center for Supercomputing Applications (NCSA) and which is supported by funds from the University of Illinois at Urbana-Champaign. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (Awards No. OCI-0725070 and\u00A0No. ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications.