Materials containing non-Kramers magnetic ions can show unusual quantum excitations because of the exact mapping of the two-singlet crystal-field ground state to a quantum model of Ising spins in a transverse magnetic field. Here, we model the magnetic excitation spectrum of garnet-structured Ho3Ga5O12, which has a two-singlet crystal-field ground state. We use a reaction-field approximation to explain published inelastic neutron-scattering data [Zhou et al., Phys. Rev. B 78, 140406(R) (2008)] using a three-parameter model containing the magnetic dipolar interaction, the two-singlet crystal-field splitting, and the nuclear hyperfine coupling. Our study clarifies the magnetic Hamiltonian of Ho3Ga5O12, reveals that the nuclear hyperfine interaction drives magnetic ordering in this system, and provides a framework for quantitative analysis of magnetic excitation spectra of materials with singlet crystal-field ground states.
@article{arxiv.1908.03530,
title = {Modeling Spin Dynamics in the Singlet Ground State Garnet Ho3Ga5O12},
author = {Joseph A. M. Paddison and Paromita Mukherjee and Xiaojian Bai and Zhiling Dun and Christopher R. Wiebe and Haidong Zhou and Jason S. Gardner and Martin Mourigal and Siân E. Dutton},
journal= {arXiv preprint arXiv:1908.03530},
year = {2019}
}