Effect of quantum fluctuations on structural phase transitions in SrTiO_3 and BaTiO_3

TL;DR

This study uses advanced simulations to explore how quantum fluctuations influence structural phase transitions in SrTiO3 and BaTiO3, revealing differential effects on ferroelectric and antiferrodistortive transitions and quantifying transition temperature shifts.

Contribution

It provides the first detailed analysis of quantum fluctuation effects on phase transitions in these perovskite materials using path-integral Monte Carlo and ab initio methods.

Findings

Quantum fluctuations suppress ferroelectric transition in SrTiO3.

Quantum fluctuations lower transition temperatures in BaTiO3.

Effects are more pronounced on ferroelectric than antiferrodistortive transitions.

Abstract

Using path-integral Monte Carol simulations and an ab initio effective Hamiltonian, we study the effects of quantum fluctuations on structural phase transitions in the cubic perovskite compounds SrTiO3 and BaTiO3. We find quantum fluctuations affect ferroelectric (FE) transitions more strongly than antiferrodistortive (AFD) ones, even though the effective mass of a single FE local mode is larger. For SrTiO3 we find that the quantum fluctuations suppress the FE transition completely, and reduce the AFD transition temperature from 130K to 110K. For BaTiO3, quantum fluctuations do not affect the order of the transition, but do reduce the transition temperature by 35-50 K. The implications of the calculations are discussed.