Magnetotransport in manganites and the role of quantal phases II: Experiment

TL;DR

This paper investigates the Hall resistivity in manganite single crystals, revealing unexpected sign behavior and proposing a new model involving quantal phases to explain the anomalous Hall effect.

Contribution

It introduces a novel model for the anomalous Hall effect in manganites that incorporates the quantal phase from double-exchange and three-site hopping mechanisms.

Findings

Opposite signs of ordinary and anomalous Hall contributions at low temperature.

The anomalous Hall resistivity is solely determined by magnetization near Tc.

The new model reproduces the observed Hall effect behavior.

Abstract

As in conventional ferromagnets, the Hall resistivity rho_xy of a La_{2/3}(Ca,Pb)_{1/3}MnO_3 single crystal exhibits both ordinary and anomalous contributions at low temperature. However, these contributions, unexpectedly, have opposite signs. Near Tc, the ordinary contribution is no longer evident and rho_xy is solely determined by the sample magnetization, reaching an extremum at approximately 40% of the saturated magnetization. A new model for the anomalous Hall effect, incorporating the quantal phase accumulated by double-exchange, three-site hopping reproduces this result. Below Tc, rho_xy reflects the competition between normal and anomalous Hall effects.