Anomalous Hall effect in Pt/La0.67Sr0.33MnO3 heterojunctions

Many emergent and novel phenomena occur in nonmagnetic/ferromagnet heterostructures. In particular, Pt/ferromagnet heterostructures where the Pt has strong spin-orbit coupling and thus can convert spin current into charge current, has attracted a great attention recently. The anomalous Hall effect (AHE) has been found in many Pt/ferromagnet heterostructures. However, the underlying physics remains elusive, so it is necessary to find more heterostructures in order to provide more experimental data. In this work, we investigate anomalous Hall resistances (AHRs) in Pt thin films sputtered on epitaxial La0.67Sr0.33MnO3 (LSMO) ferromagnetic films. High-quality Pt/LSMO heterojunctions are fabricated by pulsed laser deposition and RF-magnetron sputtering. The physical properties of LSMO films are characterized by the measurements of magnetic and transport properties. The AHR mainly contributed by Pt in the Pt/LSMO heterojunction increases sharply with temperature decreasing and changes its sign below 40 K. Furthermore, the AHR decreases sharply with the increase of Pt thickness. Those facts suggest that the ferromagnetism of Pt originates from interface due to magnetic proximity effect. Interestingly, this heterojunction can exhibit possible signal of topological Hall effect under low applied magnetic field. The above results provide an experimental basis for further understanding the interactions between electron spin and charge transport in nonmagnetic/ferromagnetic heterostructures.

Automated summary

Many emergent and novel phenomena occur in nonmagnetic/ferromagnet heterostructures. Pt/ferromagnet heterostructures, where Pt has strong spin-orbit coupling and can convert spin current into charge current, have attracted significant attention. This study investigates the anomalous Hall resistances (AHRs) in Pt thin films sputtered on epitaxial LSMO ferromagnetic films. High-quality Pt/LSMO heterojunctions are fabricated and characterized, revealing the origin of ferromagnetism in Pt and the possible presence of a topological Hall effect.