Mesoscopic ring in a magnetic field: Reactive and dissipative response

摘要: The response of a normal-metal ring threaded by magnetic field and coupled to dissipative external bath is studied via the Kubo formalism. Unlike in wire, diamagnetic contribution induced current multiply connected geometry not completely canceled paramagnetic term, resulting persistent ring. We find nonzero reactive Im\ensuremath{\sigma} which periodic function flux through with period ${\ensuremath{\varphi}}_{0}$=hc/e for single ring, but ${\ensuremath{\varphi}}_{0}$/2 an array disconnected rings. residual effects also contribute intraband scattering It shown that minimum Re\ensuremath{\sigma} zero seen experiments obtained upon proper inclusion (often omitted) addition usual interband scattering. A new regime appears functions where quantum size effects, i.e., sensitivity discreteness energy levels, are probed when broadening levels \ensuremath{\gamma} temperature T much less than typical spacing between \ensuremath{\delta}E.