2025/11/23 by Longo, Emanuele, Fontcuberta, Josep, Vavassori, Paolo
Physics and Astronomy · Materials Science · #Magnetic properties of thin films #Heusler alloys: electronic and magnetic properties #Chemical and Physical Properties of Materials
paper · doi:10.48550/arxiv.2511.18443
Charge to spin (orbital) momentum conversion phenomena enclose great potential for advancing applications in spin/orbitronics. Although current-induced magnetic moment accumulation is crucial both for fundamental understanding and practical applications, direct quantifications are scarce. Optical polarization measurements, namely magneto-optical Kerr rotation (MOKE) (θK), have been used to get direct evidence of magnetic accumulation perpendicular to a current flow density (J) in late transition metals (Pt) as well as in light transition elements (Ti, Cr), and used to conclude evidence of spin or orbital momentum accumulation. However, discrepancies of the reported θK/J values, exceeding one order of magnitude, together with early claims that conventional MOKE experiments were not a suitable tool, is prompting revisions of methods and results. Here, we report on a new methodology for MOKE measurements that solves known bottlenecks. We obtain a sensitivity of (354 ± 27) nV/nrad and use the designed protocol to measure |θKS/J| = (7.92 ± 1.94) nrad/(107 A/cm2) and |θKP/J| = (6.89 ± 1.74) nrad/(107 A/cm2) in a 50 nm thick Pt bar for S and P polarized incident light, respectively.The extracted value of |θKS/J| is significantly smaller, about a 7-fold reduction, than previous results on a nominally identical device. Given that differences in the microstructure of Pt films cannot account for such large discrepancy, this implies that experimental procedures and models should be revised accordingly.