Study of the hidden-order of URu₂Si₂by point contact tunnel junctions

Abstract

URu2Si2 presents superconductivity at temperatures below 1.5 K and a hidden order (HO) at about 17.5 K. Both electronic phenomena are influenced by Fano and Kondo resonances. At 17.5 K the HO was related in the past to a Peierls distortion that produces an energy gap deformed by the resonances. This order has been studied for more than 20 years and still there is no clear understanding. In this work we studied the electronic characteristics of URu2Si2 in a single crystal, with tunneling and metallic point contact spectroscopies. In the superconducting state, we determined the energy gap, which shows the influence of the Fano and Kondo resonances. At temperatures where HO is observed, the tunnel junctions spectra show the influence of the two resonances. Tunnel junction characteristics show that the Fermi surface nesting depends on the crystallographic direction.

Pb induces superconductivity in Bi2Se3 analyzed by point contact spectroscopy

“…This anomalous characteristic looks quite similar to the observed and found in heavy superconductor and in other physical systems. For example similar characteristics were found in URu 2 Si 2 [33]. The anomaly was related to a Fano resonance [34], and here in these experiments the anomaly could be explained as an extra interaction still not considered in the TI.…”