Orbital angular momentum contribution to angular dependent magnetoresistance in Tm3Fe5O12/Pt/CuOx films

Abstract

Recently, orbital angular momentum (OAM) has been experimentally proven to be an effective method for manipulating magnetic moments in magnetic metal systems. However, OAM cannot directly interact with magnetic insulators, as demonstrated by angular dependent magnetoresistance (ADMR) measurements. To further elucidate the effect of OAM on ADMR, a heavy metal layer was introduced between TmIG and CuOx. This allows the OAM to be transformed into spin angular momentum (SAM) via spin–orbit coupling (SOC). Comparing the ADMR of TmIG/Pt and TmIG/Pt/CuOx heterostructures, we confirmed that the transformed SAM maintains the polarized direction of OAM, leading to an increased magnetoresistance as the magnetic field rotated in yz-plane [MR(β)]. The contribution of OAM to MR(β) in the TmIG/Pt/CuOx heterostructure exhibits a similar temperature dependence to the spin Hall magnetoresistance in the TmIG/Pt heterostructure. Moreover, the contribution of OAM continuously increases with the thickness of the Pt layer, indicating a gradual transformation of OAM to SAM via SOC throughout the depth of the Pt layer. These findings not only reveal the diffusion process of OAM in the heavy metal Pt layer but also provide an important clue toward quantitatively understanding the OAM contribution to magnetization dynamics.