Identification and mechanical control of ferroelastic domain structure in rhombohedral CaMn$_7$O$_{12}$

TL;DR

This study reveals ferroelastic domain structures in CaMn$_7$O$_{12}$, demonstrating domain switching via uniaxial compression and providing a systematic method to determine domain orientations at room temperature.

Contribution

We identify ferroelastic domains in CaMn$_7$O$_{12}$ and develop a systematic Raman spectroscopy method for microscopic domain orientation determination, enabling room-temperature domain control.

Findings

Two types of ferroelastic domain walls identified.

Domains can be switched and detwinned at room temperature.

Systematic microscopic domain orientation determination established.

Abstract

We report on observation of ferroelastic domain structure in single crystals of multiferroic CaMn$_7$O$_{12}$ at room temperature. Two types of ferroelastic domain wall are found, consistent with the material's rhombohedral symmetry that is reduced from cubic symmetry at higher temperatures. Using Raman spectroscopy along with other measurements, we develop a systematic method to determine the microscopic domain orientation. Moreover, we find a switching behavior of the domains, which allows us to detwin the crystals conveniently at room temperature using a moderate uniaxial compression. Our result paves the way for further spectroscopic study and domain engineering in CaMn$_7$O$_{12}$.