PHASE OF AHARONOV-BOHM OSCILLATIONS IN CONDUCTANCE OF MESOSCOPIC SYSTEMS

Motivated by a recent experiment we analyze in detail the phase of Aha ronov-Bohm oscillations across a 1D ring with a stub coupled to one of its arms, in the presence of a magnetic flux. We demonstrate that the re are two kinds of conductance extremas. One class of them are fixed at particular flux values and can only change abruptly from a maxima t o a minima as incident energy is varied. We show a different mechanism for such abrupt phase change in conductance oscillation. We demonstra te that these extremas can exhibit ''phase locking''. However, the sec ond kind of extremas can shift continuously as the incident energy is varied.