Tunneling and microcontacts on PbTe dots created by STM

Nanometer-sized features have been created on crystalline PbTe and have been studied by means of scanning tunneling spectroscopy and point-contact spectroscopy at 4.2 K. A zero-bias dip has been observed in the tunneling density of states measured at the mounds. The magnetoresistance of point contacts adjusted to the top of the mounds reveals negative magnetoresistance and suppression of Shubnikov—de Haas oscillations. The results give evidence for the disordered metallic nature of the mounds.