Nonlinear spin transport in a rectifying ferromagnet/semiconductor Schottky contact

The electrical creation and detection of spin accumulation in ferromagnet/semiconductor Schottky contacts that exhibit highly nonlinear and rectifying electrical transport is evaluated. If the spin accumulation in the semiconductor is small, the expression for the spin voltage is identical to that of linear transport. However, if the spin accumulation is comparable to the characteristic energy scale that governs the degree of nonlinearity, the spin detection sensitivity and the spin voltage are notably reduced. Moreover, the nonlinearity enhances the backflow of spins into the ferromagnet and its detrimental effect on the injected spin current, and the contact resistance required to avoid backflow is larger than for linear transport. It is also shown that by virtue of the nonlinearity, a nonmagnetic metal contact can be used to electrically detect spin accumulation in a semiconductor.