Abstract
The magnetism of the rocksalt fcc rare-earth monopnictide HoBi, a candidate topological material with extreme magnetoresistance, is investigated. From the Ho3+ non-Kramers J=8 spin-orbital multiplet, the cubic crystal electric field yields six nearly degenerate low-energy levels. These constitute an anisotropic magnetic moment with a Jahn-Teller-like coupling to the lattice. In the cubic phase for T>TN=5.72(1)K, the paramagnetic neutron scattering is centered at k=(121212) and was fit to dominant antiferromagnetic interactions between Ho spins separated by {100} and ferromagnetic interactions between spins displaced by {12120}. For T<TN, a type-II AFM long-range order with k=(121212) develops along with a tetragonal lattice distortion. While neutron diffraction from a multidomain sample cannot unambiguously determine the spin orientation within a domain, the bulk magnetization, structural distortion, and our measurements of the magnetic excitations all show the easy axis coincides with the tetragonal axis. The weakly dispersive excitons for T<TN can be accounted for by a spin Hamiltonian that includes the crystal electric field and exchange interactions within the random phase approximation.
Original language | English |
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Article number | 104423 |
Journal | Physical Review B |
Volume | 107 |
Issue number | 10 |
DOIs | |
State | Published - Mar 1 2023 |
Funding
This work was supported as part of the Institute for Quantum Matter, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0019331. C.B. was further supported by the Gordon and Betty Moore foundation EPIQS program under Grant No. GBMF9456. The work at Boston College was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Physical Behavior of Materials under Award No. DE-SC0023124. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC). We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce. Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. The identification of any commercial product or trade name does not imply endorsement or recommendation by the National Institute of Standards and Technology. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.