We investigate the crystallographic and magnetic properties of a chromium-based thiospinel CuGaCr4S8. From a synchrotron x-ray diffraction experiment and structural refinement, Cu and Ga atoms are found to occupy the tetrahedral A-sites in an alternate way, yielding breathing pyrochlore Cr network. CuGaCr4S8 undergoes a magnetic transition associated with a structural distortion at 31 K in zero magnetic field, indicating that the spin-lattice coupling is responsible for relieving the geometrical frustration. When applying a pulsed high magnetic field, a sharp metamagnetic transition takes place at 40 T, followed by a 1/2-magnetization plateau up to 103 T. These phase transitions accompany dielectric anomalies, suggesting the presence of helical spin correlations in low-field phases. The density-functional-theory calculation reveals that CuGaCr4S8 is dominated by antiferromagnetic and ferromagnetic exchange couplings within small and large tetrahedra, respectively, in analogy with CuInCr4S8. We argue that A-site-ordered Cr thiospinels serve as an excellent platform to explore diverse magnetic phases along with pronounced magnetoelastic and magnetodielectric responses.
@article{arxiv.2303.10671,
title = {Breathing pyrochlore magnet CuGaCr$_{4}$S$_{8}$: Magnetic, thermodynamic, and dielectric properties},
author = {M. Gen and H. Ishikawa and A. Miyake and T. Yajima and H. O. Jeschke and H. Sagayama and A. Ikeda and Y. H. Matsuda and K. Kindo and M. Tokunaga and Y. Kohama and T. Kurumaji and Y. Tokunaga and T. Arima},
journal= {arXiv preprint arXiv:2303.10671},
year = {2023}
}