Fig. 4: Schematic diagram of optical control of the PMA and the RKKY. | Nature Communications

Fig. 4: Schematic diagram of optical control of the PMA and the RKKY.

From: Optical control of RKKY coupling and perpendicular magnetic anisotropy in a synthetic antiferromagnet

Fig. 4

a Diagram of how fs-laser excitations modulate the RKKY coupling and the PMA in a SAF system. Upon fs excitations, the pump photon energy (1.55 eV) excites electrons in Ru (indicated by the red vertical arrow) from occupied states below the Fermi level EF to unoccupied trapping states above EF, resulting a down-shift of the Fermi level from EF to EF’. Considering the parabolic band dispersion at the Ru interface, a downshift of EF can result in a decrease in the RKKY coupling. Meanwhile, at the Co/Pt interface such a ΔEF shift will cause electron redistributions between dxz and dyz orbitals due to a smaller energy gap, thus causing a concomitant reduction of the PMA. b Transient hysteresis loops recorded at 0.063 ps under different pump fluences for a thin [Co/Pt]4 film. c Extracted HC values from the [Co/Pt]4 thin film and from the soft layer in the SAF sample as a function of pump fluence. Here, the [Co/Pt]4 stack is inserted in a sample structure of Ta(4)/Pt(4)/[Pt(0.6)/Co(0.6)]4/Ta(2) without the RKKY coupling. Error bars indicate the uncertainty in determining the displayed value from the experimentally measured data.

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