Depth Profile of the Phase Transition of the FeRh Alloy in FeRh/BaTiO3

TL;DR

This study investigates how the phase transition in FeRh alloy within a multiferroic heterostructure depends on depth, temperature, and electric fields, revealing electric field-induced control of the transition propagation.

Contribution

It demonstrates that electric fields can fundamentally alter the depth profile of the phase transition in FeRh/BaTiO3, a novel control mechanism in multiferroic materials.

Findings

Temperature induces a uniform phase transition across the FeRh layer.

Magnetic field does not influence the phase transition mechanism.

Electric field triggers a sudden propagation of the phase transition from substrate upwards.

Abstract

We report on the depth dependence and technological limits of the phase transition of the iron rhodium alloy as function of temperature, external magnetic and electric fields in the FeRh/BaTiO3 multiferroic, determined by grazing-incidence nuclear resonant scattering measurements. The change of temperature induces a continuous and homogenous antiferromagnetic / ferromagnetic phase transition through the entire FeRh layer, except in the near substrate region. External magnetic field does not affect this mechanism, but the application of electric field changes it fundamentally (via piezoelectric strain): the phase transition of the alloy suddenly propagates from the substrate up to a height, defined by the combination of temperature and external magnetic field, as soon as the applied electric field reaches ~ 20 kV/m.