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Hard correlation gap observed in quench-condensed ultrathin beryllium
E Bielejec1, J Ruan, W Wu
1Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Physical Review Letters
|July 20, 2001
Summary
We observed a hard correlation gap in the tunneling density of states (DOS) of disordered beryllium (Be) films at millikelvin temperatures. This gap formation is linked to a drastic decrease in conductance as temperature lowers.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Disordered ultrathin films exhibit unique electronic properties.
- The tunneling density of states (DOS) is crucial for understanding electron transport.
Purpose of the Study:
- Investigate the tunneling DOS in strongly disordered ultrathin Be films.
- Characterize the temperature dependence of the DOS and conductance.
- Determine the conditions for correlation gap formation.
Main Methods:
- Quench condensation of ultrathin Be films at 20 K.
- Tunneling spectroscopy measurements.
- Variable temperature measurements from 20 K down to mK.
Main Results:
- Observed a logarithmic anomaly in DOS above 5 K.
- Found a linear dependence of DOS on energy near 2 K.
- Demonstrated a drastic decrease in zero-bias conductance with decreasing temperature.
- Conclusively revealed a hard correlation gap in the DOS at mK temperatures.
Conclusions:
- The study confirms the opening of a hard correlation gap in disordered Be films at low temperatures.
- The observed phenomena are consistent with theoretical predictions for electron-electron interactions in disordered systems.