First principles calculation for Gilbert damping constants in ferromagnetic/non-magnetic junctions

• Main Authors: R. Hiramatsu, D. Miura, A. Sakuma
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2018-05-01
• Series: AIP Advances
• Online Access: http://dx.doi.org/10.1063/1.5007255

We evaluated an intrinsic α in ferromagnetic (FM)/non-magnetic (NM) junctions from first principles (FM = Co, Fe, and Ni and NM = Cu, Pd, and Pt) to investigate the effects of the inserted NM layer. α is calculated by liner muffin-tin orbital methods based on the torque-correlation model. We confirmed that Gilbert damping is enhanced and saturated as NM thickness increases, and that the enhancement is greater in NM materials having a stronger spin-orbital interaction. By contrast, the calculated FM thickness dependences of α show that Gilbert damping tends to decrease and be saturated as the FM thickness increases. Under the torque-correlation model, the dependences of α on FM and NM thickness can be explained by considering the electronic structure of the total system, including junction interfaces, which exhibit similar behaviors derived by spin pumping theory.