Pseudo-Gap Features of Intrinsic Tunneling in HgBr_2-Bi2212 Single Crystals
Abstract
The c-axis intrinsic tunneling properties of 7-10 unit-cell-high mesas on the surfaces of Bi2212 and HgBr_2-Bi2212 single crystals were measured. The dynamic conductance shows both sharp peaks corresponding to the superconducting energy gap (SG) and a dip feature beyond the gap, followed by a wide maximum, which represents the pseudo-gap (PG). While both gaps are <A HREF=http://fy.chalmers.se/ yurgens/PG_IV1.gif>distinct</A> at low temperatures, the SG feature <A HREF=http://fy.chalmers.se/ yurgens/PG_IV2.gif>looses its distinctiveness</A> on approaching T_c. The PG feature is seen up to T ~ 200-250 K. This implies that the two gaps are independent. The <A HREF=http://fy.chalmers.se/ yurgens/intercalation.gif>intercalation</A> of Bi2212 with HgBr_2-molecules results in a drastic increase of the c-axis lattice constant and resistivity ρ_c. Despite this, the overall shape of the ρ_c(T)-dependence and the characteristic temperature T at which an upturn in ρ_c(T)- dependence sets in upon cooling <A HREF=http://fy.chalmers.se/ yurgens/PG1.gif>do not change</A>, implying that PG derives from properties of CuO_2-bilayers, and that the coupling between the bilayers does not affect T^*.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2000
- Bibcode:
- 2000APS..MARV12003Y