We explore the spin physics, novel spin related phenomena and proximity effects that emerge in quantum materials and their heterostructures. We seek to understand and exploit the interplay of charge, spin and valley degrees of freedom for future device applications. Our current focus is to study 2D materials, topological systems and van der Waals based cross-dimensional synthetic hetero-structures for exploring:
- High quality spin transport and novel spin transport regimes: We aim to understand the underlying limiting physical mechanisms to achieving theoretically predicted ground state spin properties and explore novel spin phenomena that can emerge in low dimensional materials. We probe the spin transport in atomically clean materials and their hetero-structures to understand the spin dephasing mechanisms, spin memory loss across the ferromagent/non-magnet interfaces, and spin control using magnetic proximity effects or electric field. We are also interested in developing alternative experimental methods for spin flux generation and detection making use of the pheneomena that are consequence of reduced dimensionality.
- Magnetism and magnetic proximity effects: Magnetism and proximity effects are the exciting sub-fields of low dimensional material research. The intrinsic magnetism in atomically thin sheets of 2D materials is a new paradigm of low-dimensional phenomena. We seek to understand and exploit the atomic scale magnetism for new functionalities and device concepts. We are also interested in studying magnetic exchange field modified spin/charge transport in low dimensional materials coupled to ferromagnetic systems. Another interesting phenomenon which can originate from quantum proximity effects is the realization of non-trivial topological band gaps and realization of quantized anomalous Hall.
- Magnetization dynamics, adiabatic spin pumping and spin-charge interconversion: High frequency magnetization dynamics and spin-charge interconversion (SCI) are central to conventional spintronic systems, but have barely been explored in the context of low dimensionality. Magnetization dynamics based dynamical spin pumping has emerged as a versatile technique to generate ac and dc spin flux in wide range of materials. Spin pumping can be a preferable technique for generating spin currents in new quantum materials as this method is free of the impedance mismatch problem. We explore bilayer systems of ferromagnets and atomically thin materials (e.g. graphene, TMDs, topological insulators etc.) for spin pumping and spin-charge interconversion. Also, the realization of intrinsic magnetism in atomically thin layers of vdW materials (2D-FMs) provides us with an opportunity to study and understand the magnetization dynamics in the 2D limit- a regime which has never been explored before.
Related selected publications:
1) Simranjeet Singh, Jyoti Katoch, et. al. "Strong modulation of spin currents in bilayer graphene by static and fluctuating proximity exchange fields," Physical Review Letters 118, 187201 (2017).
2) Jinsong Xu, Simranjeet Singh, Jyoti Katoch, et. al. "Spin inversion in graphene spin valves by gate-tunable magnetic proximity effect at one-dimensional contacts", Nature Communications, volume 9, Article number: 2869 (2018).
3) Simranjeet Singh*, Jyoti Katoch*, et. al. "Strontium oxide tunnel barriers for high quality spin transport and large spin accumulation in graphene", Nano Letters 17, 7578–7585 (2018).
4) S. Singh et. al. "Dynamical spin injection at a quasi-one-dimensional ferromagnet-graphene interface," Applied Physics Letters 106, 032411 (2015).