Ultrafast Orbital-Oriented Control of Magnetization in Half-Metallic La<sub>0.7</sub> Sr<sub>0.3</sub> MnO<sub>3</sub> Films.

Liu, Bo; Niu, Wei; Chen, Yongda; Ruan, Xuezhong; Tang, Zhixiong; Wang, Xuefeng; Liu, Wenqing; He, Liang et al. · Adv Mater · 2019

basic_science · Level V

Where this comes from

Abstract

Manipulating spins by ultrafast pulse laser provides a new avenue to switch the magnetization for spintronic applications. While the spin-orbit coupling is known to play a pivotal role in the ultrafast laser-induced demagnetization, the effect of the anisotropic spin-orbit coupling on the transient magnetization remains an open issue. This study uncovers the role of anisotropic spin-orbit coupling in the spin dynamics in a half-metallic La<sub>0.7</sub> Sr<sub>0.3</sub> MnO<sub>3</sub> film by ultrafast pump-probe technique. The magnetic order is found to be transiently enhanced or attenuated within the initial sub-picosecond when the probe light is tuned to be s- or p-polarized, respectively. The subsequent slow demagnetization amplitude follows the fourfold symmetry of the <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><msub><mi>d</mi> <mrow><msup><mi>x</mi> <mn>2</mn></msup> <mo>-</mo> <msup><mi>y</mi> <mn>2</mn></msup> </mrow> </msub> </mrow> </math> orbitals as a function of the polarization angles of the probe light. A model based on the Elliott-Yafet spin-flip scatterings is proposed to reveal that the transient magnetization enhancement is related to the spin-mixed states arising from the anisotropic spin-orbit coupling. The findings provide new insights into the spin dynamics in magnetic systems with anisotropic spin-orbit coupling as well as perspectives for the ultrafast control of information process in spintronic devices.