Anomalous Hall effect in magnetic insulator heterostructures : contributions from spin-Hall and magnetic-proximity effects

Abstract

In this letter, we study the origin of the anomalous Hall effect (AHE) in ferrimagnetic insulator Tm3Fe5O12 (TmIG)/Pt heterostructures. A monotonic decrease of the anomalous Hall resistivity (ApAHE) with decreasing temperature is observed for TmIG/Pt, and a sign reversal of ApAHEoccurs at around 80 K. With the addition of a Cu interlayer, the ApAHEsimilarly decreases as a function of temperature, but maintains the same sign across the full temperature range. This indicates that both the magnetic-proximity effect and spin Hall effect in the TmIG/Pt bilayer contribute to the AHE signal with opposing signs. The spin-Hall contribution to the AHE is dominant at room temperature but decreases with decreasing temperature. Meanwhile, the magneticproximity contribution to the AHE becomes dominant with decreasing temperatures, leading to a change of sign for ApAHE. We exclude a dominant influence of a ferrimagnetic compensation point in the temperature region by complementary magnetic hysteresis and neutron diffraction measurements. Our work, based on a simple method, sheds light on the origin of the AHE in magnetic insulator heterostructures, where the competition between the magnetic-proximity effect and spin Hall effect governs the sign and amplitude of the AHE.