Stacking faults in $\alpha$-RuCl$_3$ revealed by local electric polarization

TL;DR

This study investigates how stacking faults in $ ext{α}$-RuCl$_3$ influence its dielectric and magnetic properties, revealing local electric polarizations and the sensitivity of these properties to structural imperfections.

Contribution

It demonstrates that stacking faults induce local electric polarizations and affect magnetic phases, highlighting the importance of structural control in $ ext{α}$-RuCl$_3$ for applications.

Findings

Dielectric anomaly at 4 K linked to stacking faults.

Stacking faults induce local electric polarization.

Magnetic phases are sensitive to stacking imperfections.

Abstract

We present out-of-plane dielectric and magnetodielectric measurements of single crystallines $\alpha$-RuCl$_3$ with various degrees of stack faults. A frequency dependent, but field independent, dielectric anomaly appears at $T_{A}\:(f=100\:\mathrm{kHz})\sim$ 4 K once both magnetic transitions at $T_{N1}\sim$ 7 K and $T_{N2}\sim$ 14 K set in. The observed dielectric anomaly is attributed to the emergency of possible local electric polarizations whose inversion symmetry is broken by inhomogeneously distributed stacking faults. A field-induced intermediate phase is only observed when a magnetic field is applied perpendicular to the Ru-Ru bonds for samples with minimal stacking faults. Less pronounced in-plane anisotropy is found in samples with sizable contribution from stacking imperfections. Our findings suggest that dielectric measurement is a sensitive probe in detecting the structural and magnetic properties, which may be a promising tool especially in studying $\alpha$-RuCl$_3$ thin film devices. Moreover, the stacking details of RuCl$_3$ layers strongly affect the ground state both in the magnetic and electric channels. Such a fragile ground state against stacking faults needs to be overcome for realistic applications utilizing the magnetic and/or electric properties of Kitaev based physics in $\alpha$-RuCl$_3$.