Analysis of the two-dimensional Datta–Das spin field effect transistor

An analytical expression is derived for the conductance modulation of a ballistic two-dimensional Datta–das spin field effect transistor (SPINFET) as a function of gate voltage. Using this expression, we show that the recently observed conductance modulation in a two-dimensional SPINFET structure does not match the theoretically expected result very well. This calls into question the claimed demonstration of the SPINFET and underscores the need for further careful investigation.