[8p-E217-1~15] 9.5 New functional materials and new phenomena

1:30 PM - 1:45 PM JST(4:30 AM - 4:45 AM UTC)English Presentation

[8p-E217-1] Magneto-optical observation of electrically generated orbital polarization in pristine Cu and oxidized Cu

〇(P)KyungHun Ko¹, Daegeun Jo^2,3, Peter M. Oppeneer^2,3, Hyun-Woo Lee^4,5, Gyung-Min Choi¹ (1.Sungkyunkwan Univ., 2.Uppsala Univ., 3.Wallenberg Initiative Materials Science for Sustainability, 4.POSTECH, 5.Center for Quantum Dynamics of Angular Momentum)

Keywords:

Orbitronics,Spintronics,Magneto-optic

Orbital angular momentum transport is attracting growing interest as a central ingredient of magnetic phenomena. Notably, recent experiments on orbital torque and terahertz emission studies have suggested efficient charge-to-orbital conversion in oxidized Cu. However, direct evidence for orbital generation in Cu has remained lacking. Here we use magneto-optical Kerr effect measurements to detect current-induced orbital accumulation in pristine and naturally oxidized Cu films. The contrasting thickness dependences of the Kerr signals allow us to separate two orbital generation channels: the bulk orbital Hall effect in pristine Cu and the interfacial orbital Rashba–Edelstein effect at the Cu/CuOx interface. Both the extracted orbital diffusion length and diffusion constant are nearly two orders of magnitude smaller than their spin counterparts in Cu. These findings provide direct evidence of current-induced orbital accumulation in Cu and distinguish bulk orbital Hall and interfacial orbital Rashba–Edelstein mechanisms. They further reveal the sharply contrasting transport characteristics of orbital and spin angular momentum.