Scanning tunneling spectroscopic evidence for magnetic-field–induced microscopic orders in the high-Tc superconductor YBa2Cu3O7-A. D. Beyer1, M. S. Grinolds1, M. L. Teague1, S. Tajima2 and N.-C. Yeh1
1 Department of Physics, California Institute of Technology - Pasadena, CA 91125, USA
2 Department of Physics, Osaka University - Osaka 560-0043, Japan
received 5 April 2009; accepted in final form 23 July 2009; published August 2009
published online 26 August 2009
We report spatially resolved tunneling spectroscopic evidence for field-induced microscopic orders in the high-Tc superconductor YBa2Cu3O7-. The spectral characteristics inside vortices reveal a pseudogap (VCO) larger than the superconducting gap as well as a subgap smaller than , and the spectral weight shifts steadily from to VCO and upon increasing magnetic field. Additionally, energy-independent conductance modulations at 3.6 and 7.1 lattice constants along the Cu-O bonding directions and at 9.5 lattice constants along the nodal directions are manifested in the vortex state. These wave vectors differ fundamentally from the strongly dispersive modes due to Bogoliubov quasiparticle scattering interferences and may be associated with field-induced microscopic orders of pair-, charge- and spin-density waves.
74.50.+r - Tunneling phenomena; point contacts, weak links, Josephson effects.
74.25.Op - Mixed states, critical fields, and surface sheaths.
74.72.Bk - Y-based cuprates.
© EPLA 2009