Interplay of strain and magnetism in La1-xSrxMnO3 from first principles

The structural, electronic, and magnetic properties of La0.625Sr0.375MnO3 under planar and orthogonal (i.e., uniaxial) strains are investigated from first-principles generalized gradient approximation (GGA) and GGA+U approaches. We analyze a series of magnetic phase transitions from ferromagnetic to A-type and C-type antiferromagnetic orderings caused by uniaxial strain at various in-plane lattice constants. The competition between ferromagnetic and antiferromagnetic interactions obeys the following general rule: antiferromagnetic coupling is enhanced in the direction parallel to applied strain, while ferromagnetic coupling is enhanced in the orthogonal direction. The microscopic mechanisms at the basis of the strain effects are analyzed in detail.