Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional Ca$_2$CoSi$_2$O$_7$ crystal

TL;DR

This study reveals a giant magnetoelectric effect in Ca$_2$CoSi$_2$O$_7$ caused by a magnetic-field-induced transition from canted antiferromagnetic to paramagnetic state, with strong coupling between magnetic and dielectric properties.

Contribution

It demonstrates a large magnetocapacitance driven by a magnetic-field-induced magnetic phase transition in a quasi-two-dimensional crystal.

Findings

Electric polarization is induced by magnetic fields below $T_N$.

Large magnetocapacitance observed around $T_N$.

Magnetoelectric effect persists without electric poling.

Abstract

We have investigated the magnetic and dielectric properties of Ca$_2$CoSi$_2$O$_7$ crystal. The dielectricity and magnetism of Ca$_2$CoSi$_2$O$_7$ are strongly coupled below a canted antiferromagnetic transition temperature ($T_{\rm N}$): Magnetic fields induce electric polarization below $T_{\rm N}$. Interestingly, the magnetic-field-induced electric polarization is detected even without poling electric fields. Below $T_{\rm N}$, a canted antiferromagnetic-paramagnetic transition is induced by magnetic fields. The large magnetocapacitance is observed around $T_{\rm N}$. The origin of the large magnetocapacitance is due to the magnetic-field-induced the canted antiferromagnetic-paramagnetic transition.