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Spin-Hall effect and spin-phonon interactions in p-Si

Research paper by Paul Lou, Laura de Sousa Oliveira, Chi Tang, Javier Garay, Alex Greaney, Sandeep Kumar

Indexed on: 05 Jan '17Published on: 05 Jan '17Published in: arXiv - Physics - Mesoscopic Systems and Quantum Hall Effect



Abstract

For decades silicon has been the workhorse material for electronic devices, and the semiconductor industry has mastered exquisite control of its electronic properties. With this history of development, and due to its relatively slow spin relaxation, Si is also anticipated to be the principal material for the next generation of spintronics devices. A central requirement for spintronics devices is the generation of a pure spin current, with the spin-Hall effect considered to be more efficient for this than other methods such as injection of spin from a ferromagnetic source. P-doped silicon (p-Si) is predicted to exhibit the spin Hall effect, but to date there has been no convincing experimental evidence to confirm this, nor any practical demonstration of its use. In this article we report the interaction and coupling of spin, charge, and heat transport in p-Si. The spin Hall angle in p-Si is 10-4, which leads to insignificant spin-Hall magnetoresistance, complicating the use of traditional Hall bar spintronics characterization. Instead, we use signatures in the magneto thermal transport to reveal the spin Hall effect in p-Si. Specifically, we used well established third harmonic based resistance thermometry methods (3{\omega} method) which is facilitated by the use of free standing experimental set-ups developed using nanofabrication. We observe magneto-thermal transport behavior, which is analogous to spin Hall magnetoresistance and is called spin Hall magneto thermal resistance, or SMTR. Raman spectroscopy measurements and simulations support the conclusion that the spin-phonon interactions are the underlying mechanism for the observed behavior. The spin-phonon interactions, presented in this work, may allow thermal manipulation of spin current, which is essential for energy-efficient spintronics, spin caloritronics and energy conversion applications.