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Seminars and Colloquia


Reciprocity in spintronic devices 
Tue, Feb 20, 2018,   03:00 PM at Physics Seminar Hall 31, 2nd Floor, Main Building

Prof. Ashwin Tulapurkar
Indian Institute of Technology - Bombay

Abstract :

Spin torque has emerged as a leading candidate for manipulations of spins in a nano-magnet. Spin torque encompasses different types of torques such as spin-transfer torque, spin-orbit torque, interfacial Rashba coupling etc. The spin transfer torque effect is based on the s-d exchange interaction between spin-polarized current and localized magnetic moments. Such an interaction leads to the transfer of angular momentum from spin current to the localized moment, which results in a torque acting on the localized spin moment. In spin-orbit torque effect, the spin-orbit interaction in a non-magnet results in a spin current via spin-Hall effect and exerts a torque on neighbouring ferromagnet.


In this talk I will discuss the reciprocity between various effects used in spintronic devices viz. (1) spin-Hall effect and inverse spin-Hall effect (2) Spin transfer torque and its inverse called as spin-pumping effect (3) magneto-elastic interaction and its inverse effect. To experimentally investigate the reciprocity, we fabricated two port devices where the transmission of electrical signal between the two ports is based on above effects. The measurement of scattering parameters of the devices revealed that the generalized reciprocity relation, Sij(B)=Sji(-B) is satisfied. In certain devices, we found that if the magnetic field is fixed, the transmission of signal between the two ports has 180o phase shift. Such devices could be useful for making gyrators based on spin current.