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Timestamp: 2019-04-26 00:58:04+00:00

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Nanoscale reversal of the longitudinal magnetization (Mz) is highly desired in the ultrahigh density perpendicular magnetic recording. In this paper, an all-optical method to realize the reversal of Mz with an ultrasmall lateral size through configuring the inverse Faraday effect (IFE) is numerically proposed. This feature is achieved by optical coherent configuration of the IFE in the central and peripheral regions of the focal spot with opposite signs. By increasing the intensity of the peripheral regions to produce destructive interference, the lateral size of the reversed Mz smaller than 30 nm in one dimension in the central region can be achieved. This result is of vital importance for realizing ultrafast nanoscale perpendicular magnetic recording.
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Fig. 1 Schematic illustration of Mz reversal with an ultrasmall lateral size by the optical coherent method.
Fig. 2 The formation of x polarization with a π phase difference between the central and the peripheral regions in the focal plane. (a) The cartoon diagram illustrating the generation of the field. (b) (c) (d) The corresponding normalized calculated results. (e) The corresponding cross sections at x = 0 in the focal plane.
Fig. 3 Polarization conversions in the central and peripheral regions and the distribution of the reversed magnetization generated by the conversed light field. (a) The cartoon diagram illustrating the superposition of the light field. (b)(c) The cross sections of the normalized electric fields and the induced Hzeff at x = 0 in the focal plane. (d)-(f) Distributions of the reversed Mz in the focal plane, x-z plane, and y-z plane, respectively.
Fig. 4 (a) The variation of the FWHM of the reversed Mz in the central region versus the change of δ. (b) The distribution of the reversed Mz by introducing a grating function in (E)t3 and inserting a slit parallel to the y direction at the back aperture when δ = 20.
(3) E t2 (θ,ϕ)=− E t1 (θ,ϕ) ∑ j=1,2 e −i2πNA y 0 λR Δ y j .
(5) E t3 (θ,ϕ)= cosθ [ (cosθ−1)cosϕsinϕ cosθ+ cos 2 ϕ(1−cosθ) −sinθsinϕ ].
(8) H zeff =2γ E x E y3 e z .

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