Title: Spin mediated enhanced negative magnetoresistance in Ni80Fe20 and p-silicon bilayer,
Abstract: In this work, we present an experimental study of spin mediated enhanced
negative magnetoresistance in Ni80Fe20 (50 nm)/p-Si (350 nm) bilayer. The
resistance measurement shows a reduction of ~2.5% for the bilayer specimen as
compared to 1.3% for Ni80Fe20 (50 nm) on oxide specimen for an out-of-plane
applied magnetic field of 3T. In the Ni80Fe20-only film, the negative
magnetoresistance behavior is attributed to anisotropic magnetoresistance. We
propose that spin polarization due to spin-Hall effect is the underlying cause
of the enhanced negative magnetoresistance observed in the bilayer. Silicon has
weak spin orbit coupling so spin Hall magnetoresistance measurement is not
feasible. We use V2{\omega} and V3{\omega} measurement as a function of
magnetic field and angular rotation of magnetic field in direction normal to
electric current to elucidate the spin-Hall effect. The angular rotation of
magnetic field shows a sinusoidal behavior for both V2{\omega} and V3{\omega},
which is attributed to the spin phonon interactions resulting from the
spin-Hall effect mediated spin polarization. We propose that the spin
polarization leads to a decrease in hole-phonon scattering resulting in
enhanced negative magnetoresistance.