Role of two-dimensional monolayer MoS2 interlayer in the temperature-dependent longitudinal spin Seebeck effect in Pt/YIG bilayer structures

Abstract

Recently, significant efforts have been invested in improving the spin-voltage by inserting thin ferromagnetic interlayers, including monolayer transition metal dichalcogenide (TMDC) layers, in Pt/Y3Fe5O12 (Pt/YIG) structures at 300 K. However, the temperature dependence of the longitudinal spin Seebeck effect (LSSE) of a Pt/YIG structure with a monolayer (ML) TMDC interlayer and the physics underlying the role of the ML interlayer in the Pt/YIG system remain hitherto unexplored. Herein, we report the temperature-dependent LSSE signals of Pt/YIG bilayer and Pt/ML MoS2/YIG trilayer systems. We observed that the measured inverse spin Hall effect (ISHE) voltages of Pt/ML MoS2/YIG are similar to 27 times lower than that of the Pt/YIG system at 190-300 K. This result can be attributed to both the magnetic selection rule and diamagnetic ML MoS2 interlayer, which plays a critical role in hindering the movement of the spins generated at the interface in the Pt/YIG structure. In addition, we theoretically calculated the temperature dependent ISHE voltages by combining a conventional Boltzmann transport equation with the magnon relaxation time model, and the corresponding results consistent with the experimental results of both the Pt/YIG structures. Our finding represents an important achievement in understanding and measuring the LSSE and provides a promising platform, with a high spin-mixing conductance and thermoelectric performance, for two-dimensional interlayered Pt/YIG systems.