  We apply an analysis of time-dependent spin-polarized current in a
semiconductor channel at room temperature to establish how the magnetization
configuration and dynamics of three ferromagnetic terminals, two of them biased
and third connected to a capacitor, affect the currents and voltages. In a
steady state, the voltage on the capacitor is related to spin accumulation in
the channel. When the magnetization of one of the terminals is rotated, a
transient current is triggered. This effect can be used for electrical
detection of magnetization reversal dynamics of an electrode or for dynamical
readout of the alignment of two magnetic contacts.
