Pressure effect on the energy structure and superexchange interaction in undoped orthorhombic La2CuO4

Abstract

We studied the pressure dependences of the electronic structure and superexchange interaction [Formula: see text] (where [Formula: see text] and [Formula: see text] are antiferromagnetic (AFM) and ferromagnetic (FM) contributions) in antiferromagnetic La214 under hydrostatic, uniaxial (along [Formula: see text]-axial) 3% compressions and 1% in-plane compressions by the local density approximation with generalized tight-binding method (LDA + GTB cell approach). The changes in [Formula: see text] correlated with the experimentally known [Formula: see text] dependence are in accordance with the relation [Formula: see text], where [Formula: see text]. The in-plane pressure more effectively stabilizes the ground singlet two-hole state [Formula: see text] than the simple hydrostatic pressure, its effect on [Formula: see text] and [Formula: see text] is the largest. Within the same cell approach together with the superexchange interaction [Formula: see text], the valence band structure was calculated. Its changes with pressure clearly reproduce the k-distribution of the singlet and triplet quasi-particles over the Brillouin zone (BZ).