Spin current can be used to control the magnetization dynamics of a nano-magnet. There are various ways to generate spin current. Electrical current or heat current passing through a ferromagnet can generate spin current due to the spin dependent conductivity or spin-dependent Seebeck effect. Electrical current passing through a non-magnetic material with high spin-orbit coupling can generate spin current via the spin-Hall effect. Heat current passing through a non-magnet can also generate spin current due the spin-orbit coupling. This effect known as the spin-Nernst effect (SNE), has been shown recently by measuring thermally driven spin-Hall magneto-resistance [1-3]. We have shown that the spin-Nernst effect can be measured directly via a multi-terminal device with ferromagnetic Ni contacts on Pt . We generated heat current in the Pt and the resultant spin current was then detected by Ni contacts. The same multi-terminal device was used to measure the spin-Hall angle for comparison with spin-Nernst angle. In a further work, we have shown that the spin current generated via spin-Nernst effect can be injected into an adjacent FM layer to exert spin-transfer torque (spin-Nernst torque) . We could change the effective damping of the ferromagnet via spin-Nernst torque.
 S. Meyer et.al., Nat. Mater. 16, 977 (2017).
 P. Sheng et.al., Sci. Adv. 3, e1701503 (2017).
 D. J. Kim, et.al., Nat. Commun. 8, 1400 (2017).
 A. Bose et.al., Applied Physics Letters, 112, 162401 (2018).
 A. Bose et.al., Phys. Rev. B 98, 184412 (2018).
Polarization selectors, especially, those involving quantum dots (QDs) in photonic
crystals (PCs) are interesting as they offer scalability for planar architectures. Three-dimensional finite difference time domain simulations were used to design PC structures suitable for polarization-selective transmission of QD emission into different regions as well as polarization beam splitters with different splitting ratios. Different waveguide out couplers were also designed for these coupled waveguide PC structures. As the transmitted intensity is the net result of superposition of all scattered beams, QD position defines the coupling efficiency to different paths. A
detailed study showed that the transmission efficiency has intermediate maxima when the QD is shifted in either x- or z-directions.