Manipulating magnetoelectric energy landscape in multiferroics.

Huang, Yen-Lin; Nikonov, Dmitri; Addiego, Christopher; Chopdekar, Rajesh V; Prasad, Bhagwati; Zhang, Lei; Chatterjee, Jyotirmoy; Liu, Heng-Jui et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Magnetoelectric coupling at room temperature in multiferroic materials, such as BiFeO<sub>3</sub>, is one of the leading candidates to develop low-power spintronics and emerging memory technologies. Although extensive research activity has been devoted recently to exploring the physical properties, especially focusing on ferroelectricity and antiferromagnetism in chemically modified BiFeO<sub>3</sub>, a concrete understanding of the magnetoelectric coupling is yet to be fulfilled. We have discovered that La substitutions at the Bi-site lead to a progressive increase in the degeneracy of the potential energy landscape of the BiFeO<sub>3</sub> system exemplified by a rotation of the polar axis away from the 〈111〉<sub>pc</sub> towards the 〈112〉<sub>pc</sub> discretion. This is accompanied by corresponding rotation of the antiferromagnetic axis as well, thus maintaining the right-handed vectorial relationship between ferroelectric polarization, antiferromagnetic vector and the Dzyaloshinskii-Moriya vector. As a consequence, La-BiFeO<sub>3</sub> films exhibit a magnetoelectric coupling that is distinctly different from the undoped BiFeO<sub>3</sub> films.