Magnetoelectric coupling in a frustrated spinel studied using high-field scanning probe microscopy

TL;DR

This study demonstrates a novel high-field magnetic measurement technique using electrostatic force microscopy to detect local electric polarization in a frustrated magnet, revealing magnetoelectric coupling at the nanoscale.

Contribution

It introduces an innovative method for measuring magnetic-field-induced polarization in single crystals at nanometer resolution, overcoming limitations of traditional macroscopic detection.

Findings

Detected local electric polarization induced by magnetic fields.

Mapped charge inhomogeneities and their evolution with magnetic field.

Validated the use of electrostatic force microscopy for magnetoelectric studies.

Abstract

Below its N\'eel temperature, the frustrated magnet CdCr$_2$O$_4$ exhibits an antiferromagnetic spin-spiral ground state. Such states can give rise to a sizable magnetoelectric coupling. In this report, we measure the electric polarization induced in single-crystalline CdCr$_2$O$_4$ by a large applied magnetic field. Because the detection of a macroscopic polarization is hindered by the structural domains in the tetragonal spin-spiral phase, we have pioneered an alternative method of measuring polarization induced by high magnetic fields, using electrostatic force microscopy. This method enables us to measure polarization from nanometer sized areas of the sample surface, as well as imaging how to charge inhomogeneities change with magnetic field.