  Electrical control of spin dynamics in Bi$_{\rm 2}$Se$_{\rm 3}$ was
investigated in ring-type interferometers. Aharonov-Bohm and
Altshuler-Aronov-Spivak resistance oscillations against magnetic field, and
Aharorov-Casher resistance oscillations against gate voltage were observed in
the presence of a Berry phase of $\pi$. A very large tunability of spin
precession angle by gate voltage has been obtained, indicating that Bi$_{\rm
2}$Se$_{\rm 3}$-related materials with strong spin-orbit coupling are promising
candidates for constructing novel spintronic devices.
