Competing crystal structures in La0.5Ca0.5MnO3: conventional charge order versus Zener polarons

TL;DR

This study uses advanced computational methods to explore two competing crystal structures in La0.5Ca0.5MnO3, revealing how different electronic interactions stabilize distinct charge and magnetic orders.

Contribution

It demonstrates the dependence of ground state structures on the proportion of exact exchange in hybrid density functional calculations for La0.5Ca0.5MnO3.

Findings

Identified two stable ground states: checkerboard charge order and Zener polaron formation.

Showed the checkerboard state has CE-type magnetic order.

Found the Zener polaron state has A-type magnetic order.

Abstract

Equilibrium crystal structures for La0.5Ca0.5MnO3 have been calculated using hybrid exact exchange and density functional methods. Two distinct ground states with either conventional checkerboard charge ordering or Zener polaron formation are found depending on the proportion of exact exchange used. The checkerboard state has mixed x^2-y^2, 3x^2-r^2 and 3y^2-r^2 orbital ordering and CE-type magnetic order while the Zener polaron state has 3x^2-r^2 and 3y^2-r^2 ordering and A-type magnetic order.