Effects of Strain coupling and Marginal dimensionality in the nature of phase transition in Quantum paraelectrics

TL;DR

This paper investigates how strain coupling influences the nature of phase transitions in quantum paraelectrics, revealing conditions under which weak first order transitions occur at zero and finite temperatures, aligning with experimental observations.

Contribution

It introduces a semi-microscopic model with renormalization group analysis to explain weak first order transitions in doped SrTiO3 due to strain coupling effects.

Findings

Finite discontinuity in order parameter near quantum critical point at zero temperature.

Weak first order transition at finite temperature near quantum critical point.

Results consistent with experimental data on SrTiO3 and KTaO3.

Abstract

Here a recently observed weak first order transition in doped SrTiO3 is argued to be a consequence of the coupling between strain and order parameter fluctuations. Starting with a semi-microscopic action, and using renormalization group equations for vertices, we write the free energy of such a system. This fluctuation renormalized free energy is then used to discuss the possibility of first order transition at zero temperature as well as at finite temperature. An asymptotic analysis predicts small but a finite discontinuity in the order parameter near a mean field quantum critical point at zero temperature. In case of finite temperature transition, near quantum critical point such a possibility is found to be extremely weak. Results are in accord with some experimental findings on quantum paraelectrics such as SrTiO3 and KTaO3.