Spintronics has rapidly emerged as a highly pursued research area in
solid-state physics and devices owing to its potential application in low
power memory and logic as well as the rich physics associated with it.
Traditionally in spintronics, spin transfer torque in magnetic tunnel
junctions and spin valves has been used to manipulate ferromagnets. Spin
orbit torque has recently emerged as an alternative mechanism for
manipulating ferromagnets, which offers advantages of lower energy
consumption, simpler device structure, etc.
In a perpendicularly polarized Ta/CoFeB/MgO heterostructure, we have used
the spin orbit torque at the interface of the Ta and CoFeB layers to
manipulate the magnetic moments of the CoFeB layer. We have experimentally
demonstrated the application of this spin orbit torque in nanomagnetic
logic, which is a low power alternative to CMOS based computing. We have
shown that the spin orbit torque driven nanomagnetic logic consumes 100
times lower current than magnetic field driven nanomagnetic logic .
We have also shown through experiments and micromagnetic simulations
that spin orbit torque can be used to switch a ferromagnet in the
an external magnetic field if the ferromagnetic layer has a wedge shape.
This will be useful in low power magnetic memory technology .
We have also used the spin orbit torque in Ta/CoFeB/MgO heterostructure to
demonstrate a new kind of domain wall motion. Traditionally ferromagnetic
domain wall is known to flow along or opposite to the direction of the
current, but we show that spin orbit torque, owing to its unique symmetry,
can be used to move the domain wall orthogonal to the current direction
Future research ideas like femtosecond optical switching of magnets, low
power memory using magnetic skyrmions, piezoelectric-ferromagnet
oscillators using complex oxides, etc. will also be discussed.
1. D. Bhowmik *et al.* Nature Nanotechnology, 9, 59-63 (2014)
2. L.You, O, Lee, D. Bhowmik *et al. *under review (arxiv: 1409.0620)
3. D. Bhowmik *et al. *under review (arxiv: 1407.6137)
Debanjan Bhowmik recently graduated from the Department of Electrical Engineering and Computer Sciences, University of California Berkeley, with a PhD degree, and is currently a postdoctoral research associate there. He works in the field of magnetism and spintronics and is advised by Professor Sayeef Salahuddin. He is also a recipient of the Intel Ph.D. fellowship. Debanjan graduated from the Department of Electrical Engineering, Indian Institute of Technology Kharagpur, in 2010 with a B.Tech. degree.