Unusual ferromagnetic YMnO3 phase in YMnO3/La2 / 3Sr1 / 3MnO3 heterostructures

Abstract

By means of first-principles density functional calculations, we study the structural, magnetic and electronic properties of YMnO _3 / ${\rm L}{{{\rm a}}_{2/3}}{\rm S}{{{\rm r}}_{1/3}}$ MnO _3 heterostructures. Although in the bulk the ground state of YMnO _3 is an antiferromagnet, the YMnO _3 / ${\rm L}{{{\rm a}}_{2/3}}{\rm S}{{{\rm r}}_{1/3}}$ MnO _3 heterostructure stabilizes the ferromagnetic (FM) phase in YMnO _3 in the interface region over a wide range of Coulomb repulsion parameters. The hypothetical FM phase of bulk YMnO _3 is dielectric and due to substantial differences between the lattice constants in the ab plane, a strong magnetocrystalline anisotropy is present. This anisotropy produces a high coercivity of the unusual FM YMnO _3 that can explain the large vertical shift in the hysteresis loops observed in recent experiments (Paul et al 2014 J. Appl. Crystallogr. http://dx.doi.org/10.1107/S1600576714005871 47 http://dx.doi.org/10.1107/S1600576714005871 ). The correlation between weak exchange bias and the vertical shift is proposed, which calls for reinvestigation of various systems showing vertical shifts.

Keywords

• magnetism
• exchange bias
• interfaces
• 75.30.Gw
• 75.70.-i