Electronic ground-state hysteresis under magnetic field in GdMn$_2$O$_5$

TL;DR

This study reveals a novel magnetic and electric polarization behavior in GdMn$_2$O$_5$ under high magnetic fields, demonstrating complex phase transitions and magneto-electric coupling effects that alter the ground state.

Contribution

It provides the first experimental evidence of field-induced electric polarization along multiple axes and a new ground state in GdMn$_2$O$_5$, expanding understanding of multiferroic properties.

Findings

Field-induced magnetic transition around 12 T at low temperature

Electric polarization along both $a$ and $b$ directions observed at high field

Polarization along $a$ increases significantly after field cycling

Abstract

In this paper, we investigate the physical properties of the type II multiferroic GdMn$_2$O$_5$ material by means of neutrons scattering, electric polarization and magnetization measurements. A complex $(T,H)$ phase diagram shows up, with especially a field induced magnetic transition around 12 T at low temperature. The high field phase is accompanied by an additional electric polarization along both the $a$ and $$b directions, as authorized by symmetry, but never observed experimentally up to now. While the magnetic properties recover their initial states after driving the field back to zero, the polarization along $a$ shows a significant increase. This behavior is observed for all directions of the magnetic field. It constitutes a novel and striking manifestation of the magneto-electric coupling, resulting in the establishment of a new ground state at zero magnetic field.