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SUMMARY:Interfacial Engineering of the magnetism and spin transport in two
 -dimensional materials - Prof. Haichang Lu (Beihang University)
DTSTART:20241024T130000Z
DTEND:20241024T140000Z
UID:TALK223099@talks.cam.ac.uk
CONTACT:Bo Peng
DESCRIPTION:Two-dimensional (2D) materials are promising candidates for th
 e next generation of spintronic devices as they provide flat interfaces th
 at embed many interesting physical effects. The properties of the magnetic
  tunnel junction (MTJ) such as the magnetism and tunnel magnetoresistance 
 (TMR) effect are not only determined by the materials but also by the inte
 rfaces. For example\, room temperature magnetism is required for devices b
 ased on 2D magnets. Due to the Mermin-Wagner theorem which requires magnet
 ic anisotropy to sustain the magnetism for 2D spin-lattice\, only a dozen 
 2D magnets are experimentally realized down to the monolayer limit\, in wh
 ich few magnets can sustain magnetism at room temperature. Therefore\, fin
 ding a suitable substrate to contact the magnet\, thereby modulating the m
 agnetism is a promising way to realize high transition temperature. Here\,
  we study both the conventional substrate and the 2D substrate. For exampl
 e\, Fe4GeTe2 is a quasi-2D ferromagnet with an intrinsic Curie temperature
  (TC) approaching 300K. We show that by contacting with sapphire 001 surfa
 ce\, the Curie temperature can rise to 530K. We identify the substrate rec
 overed for the ferromagnetism. Apart from TC\, we also show that the type 
 of interface\, such as physisorbed and chemisorbed interface\, significant
 ly impacts the spin transport. We investigate the TMR effect of h-BN/Co MT
 J. TMR of MTJ with physisorbed interfaces is 1000 times higher than that o
 f chemisorbed interfaces. Finally\, we consider all van der Waals MTJ Fe4G
 eTe2/TMD/ Fe4GeTe2\, where TMD stands for transition metal dichalcogenides
 . Without interfacial bonds altering the spin injection\, we found the TMR
  can be known a priori via Brillouin zone filtering in hexagonal lattices\
 , where the MTJ can be designed to achieve ultrahigh TMR.
LOCATION:TCM Seminar Room
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