Stacking faults in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>RuCl</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> revealed by local electric polarization
Xinrun Mi, Xiao Wang, Hengrui Gui, Maocai Pi, Tingting Zheng, Kunya Yang, Yuhan Gan, Peipei Wang, Alei Li, Aifeng Wang, Liyuan Zhang, Yixi Su, Yisheng Chai, Mingquan He
Abstract
We present out-of-plane dielectric and magnetodielectric measurements of single-crystalline $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ with various degrees of stacking faults. A frequency-dependent, but field-independent, dielectric anomaly appears at ${T}_{A}(f=100\phantom{\rule{0.28em}{0ex}}\mathrm{kHz})\ensuremath{\sim}4$ K once both magnetic transitions at ${T}_{N1}\ensuremath{\sim}7$ K and ${T}_{N2}\ensuremath{\sim}14$ K set in. The observed dielectric anomaly is attributed to the emergence 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 a 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 $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ thin-film devices. Moreover, the stacking details of ${\mathrm{RuCl}}_{3}$ 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 $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$.