Multiferroic properties of an \aa kermanite Sr$_2$CoSi$_2$O$_7$ single crystal in high magnetic fields

TL;DR

This study investigates the multiferroic properties of Sr$_2$CoSi$_2$O$_7$ single crystals, revealing high-field induced electric polarization, potential orbital angular momentum contributions, and room-temperature polarization switching.

Contribution

It reports the observation of high-field induced electric polarization and polarization flip in Sr$_2$CoSi$_2$O$_7$, highlighting new magnetoelectric effects without magnetic order.

Findings

Finite electric polarization induced by high magnetic fields.

Polarization flip driven by rotating magnetic field at room temperature.

Possible involvement of orbital angular momentum in excited states.

Abstract

The magnetic and dielectric properties of \aa kermanite Sr$_2$CoSi$_2$O$_7$ single crystals in high magnetic fields were investigated. We have observed finite induced electric polarization along the c axis in high fields, wherein all Co spins were forcibly aligned to the magnetic field direction. Existence of the induced polarization in the spin-polarized state accompanied with the finite slope in the magnetization curve suggests the possible role of the orbital angular momenta in the excited states as its microscopic origin. The emergence of the field-induced polarization without particular magnetic order can be regarded as the magnetoelectric effects of the second order from the symmetry point of view. A low magnetic field-driven electric polarization flip induced by a rotating field, even at room temperature, has been successfully demonstrated.