Enhanced Spin Seebeck Effect in Monolayer Tungsten Diselenide Due to Strong Spin Current Injection at Interface. (29th June 2020)

• Record Type: Journal Article
• Authors: Lee, Sang‐Kwon; Lee, Won‐Yong; Kikkawa, Takashi; Le, Chinh Tam; Kang, Min‐Sung; Kim, Gil‐Sung; Nguyen, Anh Duc; Kim, Yong Soo; Park, No‐Won; Saitoh, Eiji
• Is Part Of: Advanced functional materials. Volume 30:Number 35(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-06-29
• Subjects: interface effect -- longitudinal spin Seebeck effect -- monolayer tungsten diselenide -- spin current -- spin mixing conductance -- spin‐to‐charge conversion -- thermoelectric generation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202003192
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: The spin current is significantly limited by the spin‐orbit interaction strength, material quality, and spin‐mixing conductance at material interfaces. Such limitations lead to spin current decay at the interfaces, which severely hinders potential applications in spin‐current‐generating thermoelectric devices. Thus, methodical studies on the enhancement of spin currents are indispensable. Herein, a novel approach for enhancing the spin current injected into a normal metal, Pt, using interface effects with a ferromagnetic insulator, yttrium iron garnet (YIG), is demonstrated. This is accomplished by inserting atomically thin monolayer (ML), tungsten diselenide (WSe2 ) between Pt and YIG layers. A comparative study of longitudinal spin Seebeck effect (LSSE) measurements is conducted. Two types of ML WSe2 (continuous and large‐area ML WSe2 and isolated ML WSe2 flakes) are used as intermediate layers on YIG film. Notably, the insertion of ML WSe2 between the Pt and YIG layers significantly enhances the thermopower, V LSSE /Δ T by a factor of approximately 5.6 compared with that of the Pt/YIG reference sample. This enhancement in the measured LSSE voltages in the Pt/ML WSe2 /YIG trilayer can be explained by the increased spin‐to‐charge conversion at the interface owing to the large spin‐orbit coupling and improved spin mixing conductance with the ML WSe2 intermediate layer. Abstract : The insertion of ML WSe2 between Pt and YIG layers significantly enhances the thermopower, V LSSE /Δ T by a factor of approximately 5.6 compared with that of the Pt/YIG reference sample. This enhancement can be explained by the increased spin‐to‐charge conversion at the interface owing to the large spin‐orbit coupling and improved spin mixing conductance with the ML WSe2 intermediate layer.