Anomalous Hall effect in La0.7Sr0.3MnO3/SrTiO3 superlattices:: Hopping transport and a probe of dimensionality

The anomalous Hall effect (AHE) in La0.7Sr0.3MnO3/SrTiO3 (LSMO/STO) superlattices was analyzed using theories of the Berry phase effect. The temperature-dependent anomalous Hall coefficient R-s is found to be expressed by -R-s=R(s0)exp[(T/T-0)(1.5)], where R-s0 is a prefactor and T-0 is in units of kelvin, and is explained by the carrier-hopping mechanism. In addition, a scaling analysis for the Hall resistivity as a function of magnetization supports the scenario of the Berry phase effects. Furthermore, a shifting extremum of Hall resistivity in LSMO/STO superlattices is observed and regarded as a probe of dimensionality in quasi-two-dimensional systems.