  We investigate spin polarized electron transport in ultra-thin
Si-Core/Ge-Shell and Ge-Core/Si-Shell nanowire system using semi-classical
Monte Carlo simulation method. Depolarization of electron's spin occurs in
nanowire mainly due to D'yakonov-Perel dephasing (DP-mechanism) and
Elliott-Yafet dephasing (EY-mechanism). We studied the dependence of spin
dephasing on ultra-thin silicon core diameter in Si-Core/Ge-Shell nanowire and
germanium core diameter in Ge-Core/Si-Shell nanowire. Variation in spin
dephasing length with varying core diameter ranging from 1 nm to 9 nm indicate
that spin dephasing length increases with increase in Si-core diameter in
Si-Core/Ge-Shell nanowire and spin dephasing length decreases with increase in
Ge-core diameter in Ge-Core/Si-Shell nanowire. We then studied the variation in
spin dephasing length with varying externally applied transverse electric field
ranging from 20 kV/cm to100 kV/cm. In the electric field dependence study we
found that spin dephasing length is weakly dependent upon applied electric
field. In the end, we studied the variation in spin dephasing length with
varying temperature in the range of 4 K to 377 K. In this simulational study we
found that for both Si-Core/Ge-Shell and Ge-Core/Si-Shell nanowire system spin
dephasing length shows a strong dependence on temperature and spin dephasing
length increases with decrease in temperature from room temperature range.
