Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si

Abstract

Spin current experiences minimal dephasing and scattering in Si due to small spin-orbit coupling and spin-lattice interactions is the primary source of spin relaxation. We hypothesize that if the specimen dimension is of the same order as the spin diffusion length then spin polarization will lead to non-equilibrium spin accumulation and emergent phase transition. In n-Si, spin diffusion length has been reported up to 6 μm. The spin accumulation in Si will modify the thermal transport behavior of Si, which can be detected with thermal characterization. In this study, we report observation of spin-Hall effect and emergent antiferromagnetic phase transition behavior using magneto-electro-thermal transport characterization. The freestanding Pd (1 nm)/ Ni80Fe20 (75 nm)/ MgO (1 nm)/ n-Si (2 micron) thin film specimen exhibits a magnetic field dependent thermal transport and spin-Hall magnetoresistance behavior attributed to Rashba effect. An emergent phase transition is discovered using self-heating 3omega method, which shows a diverging behavior at 270 K as a function of temperature similar to a second order phase transition. We propose that spin-Hall effect leads to the spin accumulation and resulting emergent antiferromagnetic phase transition. We propose that the length scale for Rashba effect can be equal to the spin diffusion length and two-dimensional electron gas is not essential for it. The emergent antiferromagnetic phase transition is attributed to the site inversion asymmetry in diamond cubic Si lattice.

arXiv comment18 pages

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Cited by in corpus (7)

• Spin Seebeck effect and thermal spin galvanic effect in Ni80Fe20/p-Si bilayers
• Large spin-Hall effect in Si at room temperature
• Spin phonon interactions and magneto-thermal transport behavior in p-Si
• Large Magnetic Moment in Flexoelectronic Silicon at Room Temperature
• Generation and detection of dissipationless spin current in MgO/Si bilayer
• Giant enhancement in Rashba spin-Seebeck effect in NiFe/p-Si thin films
• Interlayer charge transfer from contact electrification in conducting micro and nanoscale thin film heterostructures