Magnetization process of the breathing pyrochlore magnet CuInCr4S8 in ultrahigh magnetic fields up to 150 T

Abstract

The magnetization process of the breathing pyrochlore magnet ${\mathrm{CuInCr}}_{4}{\mathrm{S}}_{8}$ has been investigated in ultrahigh magnetic fields up to 150 T. Successive phase transitions characterized by a substantially wide 1/2-plateau from 65 T to 112 T are observed in this system, resembling those reported in chromium spinel oxides. In addition to the 1/2-plateau phase, the magnetization is found to exhibit two inherent behaviors: A slight change in the slope of the $M\text{\ensuremath{-}}H$ curve at $\ensuremath{\sim}85$ T and a shoulderlike shape at $\ensuremath{\sim}135$ T prior to the saturation. Both of them are accompanied by a hysteresis, suggesting first-order transitions. The theoretical calculation applicable to ${\mathrm{CuInCr}}_{4}{\mathrm{S}}_{8}$ is also shown, based on the microscopic model with the spin-lattice coupling. The calculation fairly well reproduces the main features of the experimentally observed magnetization process, including a relatively wide cant 2:1:1 phase clearly observed in the previous work [Y. Okamoto et al., J. Phys. Soc. Jpn. 87, 034709 (2018)]. The robust 1/2-plateau on ${\mathrm{CuInCr}}_{4}{\mathrm{S}}_{8}$ seems to be originated from the dominant antiferromagnetic exchange interactions and the strong spin-lattice coupling.