Femtosecond laser-heating effect on the magnetization dynamics in perpendicularly magnetized Ta/CoFeB/MgO film

Abstract

We have studied the effect of ultrafast laser-heating on the magnetization dynamics of perpendicularly magnetized CoFeB film by means of the time-resolved magneto-optical Kerr rotation effect. The effective perpendicular magnetic anisotropy field H K is significantly decreased with enhancing the pump laser-fluence in a moderate range of 5-12 mJ cm −2 . The Gilbert damping, however, is found to be independent of the pump fluence. These findings provide a new method of separately manipulating the Gilbert damping and perpendicular magnetic anisotropy.

Large anisotropy of magnetic damping in ultrathin epitaxial Fe/GaAs (0 0 1) film

“…[6][7][8][9][10][11][12][13] These reports reveal that several factors have impact on the magnetic damping constant, such as the thickness, 6 the capping layer, 7,8 and the magnetic anisotropy of the film. 9,10 In addition, external electric field and pulsed laser can also change the damping constant. [11][12][13] Theoretically, the intrinsic magnetic damping is proportional to ξ 2 /τ, where ξ is the strength of the spin-orbit interaction and τ is the electron momentum scattering time.…”

“…The details of the TR-MOKE setup were also described in the previous reports. 9,27 The sample is placed in XY-plane with [110] orientation pointing to positive x-axis as shown in Fig. 1(b).…”

“…9,14 Fig. 2(a) shows the typical TR-MOKE signal of 8 MLs Fe film measured along [1 ̅ 10] orientation.…”

Spin reorientation transition in CoFeB/MgO/CoFeB tunnel junction enabled by ultrafast laser-induced suppression of perpendicular magnetic anisotropy

“…3f ), and the 1 nm-thick CoFeB film retains the PMA even at a laser excitation as high as 12 mJ cm −2 . 58 Finally, we stress that the modified effective anisotropy parameter K eff ( J) and altered magnetization orientation in the fixed layer persist for a time period of several nanoseconds. This is evident from the measured pump-probe traces, which demonstrate that the pump-induced ellipticity changes ε(Δt ) do not relax to zero upon the decay of the oscillating part (Fig.…”

Сверхбыстрое Лазерно-Индуцированное Управление Магнитной Анизотропией Наноструктур

“…Более того, авторы [47] показали, что соответствие между описанными изменениями поля анизотропии и лазерноиндуцированным ростом температуры решетки и ее дальнейшим остыванием может быть описано в модели температурных изменений параметра магнитной анизотропии. В дальнейших работах, применяя аналогичные методики, несколько групп показали, что в различных ферромагнитных металлах и металлических сплавах возбуждение фемтосекундными лазерными импульсами и нагрев приводят к уменьшению параметров магнитокристаллической [48,49], ростовой [49,50], магнитоупругой [51] и интерфейсной [29,52] анизотропии.…”