Anharmonic stabilization of ferrielectricity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>CuInP</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math>

Abstract

Using first-principles calculations and group-theory-based models, we study the stabilization of ferrielectricity (FiE) in ${\mathrm{CuInP}}_{2}{\mathrm{Se}}_{6}$. We find that the FiE ground state is stabilized by a large anharmonic coupling between the polar mode and a fully symmetric Raman-active mode. Our results open possibilities for controlling the single-step switching barrier for polarization by tuning the Raman-active mode. We discuss the implications of our findings in the context of designing next-generation optoelectronic devices that can overcome the voltage-time dilemma.

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