Voltage-driven magneto-optical Kerr effect in a glass/Au/NiFe/dielectric/WS_2magneto-plasmonic structure

Abstract

The current study was undertaken to design a voltage-driven magneto-plasmonic device analog to a field effect transistor (FET) but alternatively proposed for a transverse magneto-optical Kerr effect (TMOKE) response. The suggested structure is a glass/Au/NiFe/dielectric/WS2 multilayer with very similar constituted layers to the substrate/metal-gate/dielectric/conductive-channel FET design. Here, a Au/NiFe bilayer is of metal that Au is individually working as a plasmonic excitation layer and NiFe is a ferromagnetic layer for a TMOKE response. The WS2 monolayer is a conductive-channel layer separated from the metal-gate layer via a dielectric layer. The WS2 refractive index and absorption/reflection can be controlled upon applying voltage to the Au/NiFe metal-gate bilayer. Light reflection and TMOKE responses from this structure in a Kretschmann configuration were determined based on a transfer matrix method. Significant change in TMOKE was predicted as the result of large changes in the refractive index of the WS2 monolayer versus voltage as recently reported by Yu et al. [Nano Lett.17, 3613 (2017)NALEFD1530-698410.1021/acs.nanolett.7b00768]. Dielectric layers having different thicknesses were examined to increase the TMOKE response and reduce the reflectance. The results offer design options for achieving miniaturized electrically driven magneto-optical response elements.