18 April (Wednesday) at 13:00 in the hall of the Academic Council of the Institute of Metal Physics
Density Waves in HTSC
Dept. of Physics and Astronomy, Seoul National University
Pseudo-Gap (PG) phase of the cuprates is believed to hold a key to the understanding of the mechanism of high Tc superconductivity. Recently, discoveries of CDW phase in PG phase have been reported on cuprate superconductors, but its detailed origin is still not fully understood. We studied PG phase of BSCCO 2212 using variable temperature STM and observed density modulations similar to the reported CDW’s wave vectors. Unlike the previously reported CDW’s, however, we find these density modulations disperse in particle - hole asymmetric manner and their correlation length is not a conventional one. On the other hand, we succeeded in realizing Scanning Josephson Tunneling Microscopy and discovered wave like features in Cooper pair density by directly probing Josephson current . In this presentation, we will discuss a new length scale in PG phase – phase coherence length of these density modulations in real space and their possible origin as well as their relation to the superconductivity by comparing these PG density waves to the recently discovered PDW (Pair Density Wave).