Tunneling density of states and conductance background in the Pb-Bi-O and Cu-O high-temperature superconductors

✍ Scribed by C.A. Chatzidimitriou-Dreismann; E.J. Brändas

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 587 KB
• Volume: 201
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90482-r

✦ Synopsis

Some recent experimental findings concerning the conductance background G (V) in tunneling measurements on Pb-Bi-O and Cu-O high-To superconductors are analysed in the general framework of scattering theory combined with complex scaling (CSM) theory. The following experimental results are interpreted from first theoretical principles: ( 1 ) the asymmetry in the slope of G(V) with respect to the sign of V (which is different in Pb-Bi-O and Cu-O systems) is caused by the breaking of particle-hole symmetry of the tunneling process; (2) the specific value of this asymmetry is determined by the strength of the pairing interaction; (3) the finite G (0) follows very generally from a fundamental property of the fermionic second-order density matrix; (4) the lifetime of the paired carriers, as given by complex scaling, and the interaction strength obey the standard energy-time uncertainty relation. These results, being due to quantum correlations, are independent of the (still unknown) mechanism (s) of the pairing interaction. Moreover, they give support for the existence of precursor states.