Properties of domain walls and magnetoresistance in low-doped La2−y SryCuO4

Abstract

The properties of the diagonal stripe structures of the Hubbard model are theoretically studied in relation to the incommensurate spin order and the magnetic effects detected in the dielectric phase of low-doped La2−ySryCuO4 (y ≤ 0.05). The mean-field approximation is used to investigate the properties of the solutions with domain walls between antiphase antiferromagnetic domains that are centered on bonds. Such periodic structures with 2l sites in a unit cell are shown to have 2(l − 1) levels in the lower and upper Hubbard subbands and two levels that are separated into the Hubbard gap and correspond to quasi-one-dimensional states localized on domain walls. The calculation results are employed to check the assumption that the low conduction of the dielectric LSCO phase occurs via the network of domain walls. The maximum relative change in the magnetoresistance during a spin-flop transition in a critical magnetic field is estimated, and the giant magnetoresistance is qualitatively explained.