Magnetic Phase Transition and Magnetization Plateau in Cs$_2$CuBr$_4$

TL;DR

This study investigates the magnetic phase transitions and the emergence of a one-third magnetization plateau in Cs$_2$CuBr$_4$, a frustrated quasi-two-dimensional spin-1/2 system, revealing anisotropic behavior and first-order phase transitions.

Contribution

It provides the first detailed experimental analysis of the magnetization plateau and phase transitions in Cs$_2$CuBr$_4$, highlighting anisotropic effects and the nature of the field-induced transition.

Findings

Magnetic phase transition at T_N=1.4 K detected.

Magnetization plateau observed at one-third saturation for H//b,c.

First-order phase transition to plateau state identified.

Abstract

The crystal structure of Cs$_2$CuBr$_4$ is the same as that of Cs$_2$CuCl$_4$, which has been characterized as a spin-1/2 quasi-two-dimensional frustrated system. The magnetic properties of Cs$_2$CuBr$_4$ were investigated by magnetization and specific heat measurements. The phase transition at zero magnetic field was detected at $T_{\rm N}=1.4$ K. It was observed that the magnetization curve has a plateau at about one-third of the saturation magnetization for magnetic field $H$ parallel to the $b$- and $c$-axes, while no plateau was observed for $H\parallel a$. The field-induced phase transition to the plateau state appears to be of the first order. The mechanism leading to the magnetization plateau is discussed.