Fig. 1: Device, schematic measurement, and pure Seebeck signal. | Communications Physics

Fig. 1: Device, schematic measurement, and pure Seebeck signal.

From: Magnetic tunnel junctions driven by hybrid optical-electrical signals as a flexible neuromorphic computing platform

Fig. 1

a Schematic of the device structure and complete measurement setup, including pulsed laser heating for thermal excitation, DC bias application, and lock-in detection of the thermoelectric voltage. b Optical microscope image of the fabricated device, showing the contact pads. c High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of a magnetic tunnel junction (MTJ) nanopillar, highlighting the multilayer stack and structural integrity. d, e Thermoelectric voltage (VAC), measured via lock-in detection under open-circuit conditions (Ibias = 0), as a function of in-plane magnetic field for MTJs with nanopillar diameters of 300 nm (d) and 800 nm (e). Different curves correspond to varying laser powers (in mW). f, g Parallel-state voltage (\({V}_{{{\rm{AC}}}}^{P}\)), antiparallel-state voltage (\({V}_{{{\rm{AC}}}}^{AP}\)), the voltage contrast (δVP,AP), and the corresponding tunnel magneto-Seebeck (TMS) ratios as a function of laser power. Solid lines denote linear fits; slopes are reported as α.

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