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arXiv · 1910.08570

Magnetic order and single-ion anisotropy in Tb$_3$Ga$_5$O$_{12}$

R. Wawrzyńczak·B. Tomasello·P. Manuel·D. Khalyavin·M. D. Le·T. Guidi·A. Cervellino·T. Ziman·M. Boehm·G. J. Nilsen·T. Fennell
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Abstract

Terbium gallium garnet (TGG), Tb$_3$Ga$_5$O$_{12}$, is well known for its applications in laser optics, but also exhibits complex low-temperature magnetism that is not yet fully understood. Its low-temperature magnetic order is determined by means of time-of-flight neutron powder diffraction. It is found to be a multiaxial antiferromagnet with magnetic Tb$^{3+}$ ions forming six sublattices of magnetic moments aligned parallel and anti-parallel to the $\langle100\rangle$ crystallographic directions of the cubic unit cell. The structure displays strong easy-axis anisotropy with respect to a two-fold axis of symmetry in the local orthorhombic environment of the Tb$^{3+}$ sites. The crystal-field splitting within the single-ion ground-state manifold is investigated by inelastic neutron scattering on powder samples. A strong temperature dependence of the quasidoublet ground-state is observed and revised parameters of the crystal-field Hamiltonian are given. The results of bulk magnetic susceptibility and magnetisation measurements are in good agreement with values based on the crystal-field model down to 20~K, where the onset of magnetic correlations is observed.

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R. Wawrzyńczak, B. Tomasello, P. Manuel, D. Khalyavin, M. D. Le, T. Guidi, A. Cervellino, T. Ziman, M. Boehm, G. J. Nilsen, T. Fennell. 2019-10-18. Magnetic order and single-ion anisotropy in Tb$_3$Ga$_5$O$_{12}$. https://doi.org/10.1103/physrevb.100.094442

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