Two-step transition in a magnetoelectric ferrimagnet Cu2OSeO3

TL;DR

This study investigates the magnetic and magnetoelectric properties of Cu2OSeO3 single crystals, revealing two magnetic transitions, domain behavior, and intrinsic magnetoelectric effects through detailed measurements.

Contribution

It provides a comprehensive analysis of magnetic transitions and magnetoelectric coupling in Cu2OSeO3, highlighting the two-step transition process and intrinsic effects.

Findings

Two magnetic transitions at 57 K and 58 K

Saturation magnetization behavior consistent with 3-up-1-down configuration

Evidence of intrinsic magnetoelectric effect below transition temperature

Abstract

We report a detailed single crystal investigation of a magnetoelectric ferrimagnet Cu2OSeO3 using dc magnetization and ac susceptibility along the three principal directions [100], [110] and [111]. We have observed that in small magnetic fields two magnetic transitions occur, one at Tc = 57 K and the second one at TN = 58 K. At Tc the non-linear susceptibility reveals the emergence of the ferromagnetic component and below Tc the magnetization measurements show the splitting between field-cooled and zero-field-cooled regimes. Above 1000 Oe the magnetization saturates and the system is in a single domain state. The temperature dependence of the saturation below Tc can be well described by m(T) = m(0)[1 - (T/Tc)^2]^{\beta}, with m(0) = 0.56 (mu)B/Cu, corresponding to the 3-up-1-down configuration. The dielectric constant measured on a thin single crystal shows a systematic deviation below the transition, indicating an intrinsic magnetoelectric effect.