Sign Reversal of Fieldlike Spin-Orbit Torque in an Ultrathin Cr/Ni Bilayer

• DOI: 10.1103/physrevapplied.9.014022
• Publication Date: 2018-01-19T14:32:50Z
• Authors: Arnab Bose; Hanuman Singh; Varun Kumar Kushwaha; Swapnil Bhuktare; Sutapa Dutta; Ashwin A. Tulapurkar
• Keywords: 0303 health sciences; Condensed Matter - Mesoscale and Nanoscale Physics; SYMMETRY; ANTIFERROMAGNET; FOS: Physical sciences; 02 engineering and technology; DRIVEN; TOPOLOGICAL INSULATOR; 7. Clean energy; ELECTRONS; HALL; 03 medical and health sciences; LAYER; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); METALS; 0210 nano-technology

In this work report unconventional sign change of field like spin orbit torque in ultra-thin Chromium(1.5nm-5nm)/Nickel(8nm) bi-layer. We performed standard spin-torque ferromagnetic resonance (ST-FMR) experiment Cr/Ni bi-layer by passing radio frequency current and measuring DC voltage. observe that when thickness Cr layer is critically low (<6nm) on Ni significantly increases. Most importantly the opposite to Oersted generated torque. To verify interracial nature torque, 2 nm thin Cu inserted between behaves same as induced Hence possible origin such could be inter-facial Rashba interaction which present but vanishes Cr/Cu/Ni hetero-structure. From our we can estimate approximately 35 Oe effective magnetic created 8 thicker layer, 1E12 A/m^2 flows through layer. All experiments are done at room temperature. So film expected behave paramagnet (Neel temperature bulk 311K). a good choice heavy metal employ large combining Hall effect interaction.