Abstract
Single-crystal neutron diffraction, inelastic neutron scattering, bulk magnetization measurements, and first-principles calculations are used to investigate the magnetic properties of the honeycomb lattice Tb2Ir3Ga9. While the Rln2 magnetic contribution to the low-temperature entropy indicates a Jeff=1/2 moment for the lowest-energy crystal-field doublet, the Tb3+ ions form a canted antiferromagnetic structure below 12.5 K. Due to the Dzyaloshinskii-Moriya interactions, the Tb moments in the ab plane are slightly canted towards b with a canted moment of 1.22 μB per formula unit. A minimal xxz spin Hamiltonian is used to simultaneously fit the spin-wave frequencies along the high-symmetry directions and the field dependence of the magnetization along the three crystallographic axes. Long-range magnetic interactions for both in-plane and out-of-plane couplings up to the second nearest neighbors are needed to account for the observed static and dynamic properties. The z component of the exchange interactions between Tb moments is larger than the x and y components. This compound also exhibits bond-dependent exchange with negligible nearest-neighbor exchange coupling between moments parallel and perpendicular to the 4f orbitals. Despite the Jeff=1/2 moments, the spin Hamiltonian is denominated by a large in-plane anisotropy Kz-1meV. DFT calculations confirm the antiferromagnetic ground state and the substantial interplane coupling at larger Tb-Tb distances.
| Original language | English |
|---|---|
| Article number | 184413 |
| Journal | Physical Review B |
| Volume | 103 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 12 2021 |
Funding
Research at ORNL's HFIR and SNS was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy (DOE). R.S.F., M.E.M., and D.P. acknowledge support by the US Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. Work in the Materials Science Division at Argonne National Laboratory (crystal growth and magnetic characterization) was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.