Journal of Physics: Condensed Matter, 2014, Vol.26(47), p.474203 (10pp)
We report low-temperature transport experiments on atomic-size contacts of bismuth that are fabricated using the mechanically controlled break-junction technique at low temperatures. We observe stable contacts with conductance values at fractions of one conductance quantum G 0 = 2 e 2 / h , as is expected for systems with long Fermi wavelength. We defer two preferred conductance scales: the lower one is in the order of 0.015 G 0 and can be attributed to single-atom Bi contact, while the higher one amounts to 0.15 G 0 , as indicated by the appearance of multiples of this value in the conductance histogram. Rich magneto-transport behaviour with significant changes in the magneto-conductance is found in the whole conductance range. Although for the pristine samples and large contacts with G 〉 5 G 0, indications for Shubnikov-de Haas oscillations are present, the smallest contacts show pronounced conductance fluctuations that decay rapidly when a magnetic field is applied. Moreover, large variations are observed when a finite bias voltage is applied. These findings are interpreted as the transition from the diffusive to the ballistic and the ultra-quantum regime when lowering the contact size.
Magnetic Fields ; Oscillations ; Conductance ; Voltage ; Decay ; Condensed Matter ; Mathematical Analysis ; Bismuth ; Condensed Matter Physics (General) (So) ; Bismuth ; Nanocontacts ; Atomic Contacts ; Break Junction ; Universal Conductance Fluctuations (Ucf) ; Shubnikov-de Haas Oscillations;
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