Tuning the structural instability of SrTiO_3 by Eu doping: The phase diagram of Sr_1-xEu_xTiO_3

TL;DR

This study investigates how Eu doping influences the structural phase transition in SrTiO_3, revealing a nonlinear increase in transition temperature and changes in lattice dynamics through experimental and theoretical analysis.

Contribution

It provides the first comprehensive phase diagram of Sr_1-xEu_xTiO_3, combining experimental measurements with theoretical modeling to understand doping effects on structural instability.

Findings

Transition temperature increases nonlinearly with Eu doping

Double-well potential becomes narrower and deeper with more Eu

Theoretical analysis explains changes in lattice dynamics

Abstract

The phase diagram of Sr_1-xEu_xTiO_3 is determined experimentally by electron paramagnetic resonance and resistivity measurements and analyzed theoretically within the self-consistent phonon approximation as a function of x ([0.03-1.0]). The transition temperature of the structural instability of the system increases nonlinearly to higher temperatures with increasing x. This is interpreted theoretically by a substantial alteration in the dynamics caused by a change in the double-well potential from broad and shallow to narrow and deep.