First principles study of c-axis strain effect on the magnetic structure and ferroelectricity in double perovskite Y2MnCrO6

Abstract

We carry out a first-principles investigation of the c-axis strain effect on the structure and multiferroicity of double perovskite Y2MnCrO6, in which the b-axis is fixed to the bulk value. The results show that the ferrimagnetic-paraelectric ground state in strain-free bulk sample is driven to a multiferroic E-type antiferromagnetic-ferroelectric state under the c-axis compressive strains above −0.3%. We also find a ferrimagnetic-to-ferromagnetic phase transition at the c-axis tensile strain of 2.2%, due to remarkably reduced octahedral distortion. Heisenberg model analysis reveals that the two phase transitions are predominantly governed by the nearest-neighboring exchange interaction in Mn layer and that along the c-axis. Moreover, the former magnetic transition under compressive strain gives rise to a finite ferroelectric polarization mainly due to the electronic contribution. The predicted polarization in the multiferroic state is significantly enhanced as compared to that of undoped orthorhombic YMnO3 and decreases monotonously with the c-axis compressive strain.