Magnetoconductance fluctuations in a strongly correlated disordered ring system at low temperatures

Abstract

Using a recursive real-space Green's-function technique in the tight-binding model, we study the influence of the electron-electron Hubbard interaction on the magnetoconductance fluctuations in a disordered ring at low temperatures. Our numerical results improve the previous theoretical predictions for the magnetoconductance fluctuations as a function of magnetic flux compared with experiments. Meanwhile, we find several anomalous phenomena at low temperatures, which do not survive at high temperatures. For the Fermi level ${\mathit{E}}_{\mathit{f}}$=0.1t (t is the hopping integral) the envelope of magnetoconductance fluctuations drops to a lower value at some magnetic flux, while the Hubbard interaction causes the drop to occur at larger flux. The magnetoconductance fluctuations vary with the Hubbard interaction for magnetic flux around 20${\mathrm{\ensuremath{\Phi}}}_{0}$(${\mathrm{\ensuremath{\Phi}}}_{0}$=hc/e) mainly in the range of small U. The Hubbard interaction narrows the widths of the main peaks in the Fourier spectrum, but it does not change their positions. \textcopyright{} 1996 The American Physical Society.