  The centrosymmetric materials with hidden spin polarization are considered to
be the promising candidates for realization of energy efficient spintronics
systems and devices. However, the control of hidden spin polarization and
resulting transport behavior is not well understood. We hypothesized that
inhomogeneous strain can be the external knob to study and control hidden spin
polarization. In this work, we demonstrate a strain gradient mediated symmetry
breaking to discover the hidden spin polarization in centrosymmetric Si
lattice. The hidden spin polarization gives rise to magnetocrystalline
anisotropy and local magnetic moment along <111> directions in the Si. The
local magnetic moment gives rise to spin-acoustic phonon coupling, which is the
underlying cause of observed spin-Hall effect in both n-Si and p-Si. Discovery
of hidden magnetic moment in Si not only challenges the fundamental
understanding of the origin of the magnetism but also presents a giant leap in
realization of spintronics systems.
