Direct imaging of thermally driven domain wall motion in magnetic insulators
Wanjun Jiang, Pramey Upadhyaya, Yabin Fan, Jing Zhao, Minsheng Wang, Li-Te Chang, Murong Lang, Kin L. Wong, Mark Lewis, Yen-Ting Lin, Jianshi Tang, Sergiy Cherepov, Xuezhi Zhou, Yaroslav Tserkovnyak, Robert N. Schwartz, and Kang L. Wang
Accepted
Thermally-induced domain wall motion in a magnetic insulator was observed using spatiotemporal resolved polar magneto-optical Kerr effect microscopy in the presence of various temperature gradients. The following results were found: (1) the domain wall moves from the cold region towards the hot region; (2) a threshold temperature gradient (5 K/mm), i.e., a minimal temperature gradient required to induce domain wall motion; (3) increasing domain wall velocity as a function of distance to the region with a temperature gradient, which is interpreted to result from the penetration of a magnonic current into the constant temperature region; and (4) a linear relation of the average domain wall velocity with positive/negative temperature gradients beyond a threshold temperature gradient. Our observations can be qualitatively explained using a magnonic spin transfer torque mechanism, which suggest the use of magnonic spin transfer torque for controlling magnetization dynamics.