American Physical Society Sites|APS|Journals|PhysicsCentral|Physics

Session W1: Invited Session: Superconductivity at High Pressure

2:30 PM–5:30 PM, Thursday, March 21, 2013
Room: Ballroom I

Sponsoring Units: DCMP DMP
Chair: Viktor Struzhkin, Carnegie Institution for Science

Abstract ID: BAPS.2013.MAR.W1.3

Abstract: W1.00003 : NMR Studies of Novel Electronic Phases in Low Dimensional Molecular Solids at High Pressure and Low Temperature*

3:42 PM–4:18 PM

Preview Abstract      Abstract  

Author:

Stuart Brown
(UCLA Physics and Astronomy)

Molecular superconductors are known for anisotropic electronic band structure, correlations, and a sensitivity to mechanical or chemical pressure which acts to control the relative strength of the respective kinetic and potential energies. Modest pressures, of order 1 GPa are commonly used to continuously tune from a Mott insulating ground state to a superconducting state, and NMR has been particularly successful in identifying the orders involved, and the nature of the excitations in the various phases encountered. The family of quasi-two dimensional systems $\kappa$-(BEDT-TTF)$_2$X ({\it e.g.}, X=Cu(NCS)$_2$, Cu[N(CN)$_2$]Cl) includes a line of first order phase transitions separating the Mott and superconducting phases, with the superconducting state exhibiting signatures for line nodes associated with an order parameter sign-change over the Fermi surface. The pressure/temperature phase diagram of the quasi-one dimensional materials (TMTSF)$_2$X, X=PF$_6$, ClO$_4$,...) includes more phases, as a consequence of effective 1/4-filling and a substantial density wave susceptibility. The SC ground state is singlet, and there is evidence for a sign-change of the order parameter over the Fermi surface. The high-conductivity normal state exhibits properties associated with two-dimensional spin fluctuations, with signatures in the relaxation rate, as well as transport that are reminiscent of behaviors observed in other correlated superconductors.

*Supported by the NSF under grant no. DMR-1105531

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2013.MAR.W1.3