Superconductivity and fluctuating magnetism in quasi two-dimensional kappa-(BEDT-TTF)2Cu[N(CN)2]Br probed with implanted muons

Abstract

A muon-spin relaxation (muSR) investigation is presented for the molecular superconductor kappa-(BEDT-TTF)2Cu[N(CN)2Br]. Evidence is found for low-temperature phase-separation, with only a fraction of the sample showing a superconducting signal, even for slow cooling. Rapid cooling reduces the superconducting fraction still further. For the superconducting phase, the in-plane penetration depth is measured to be lambda_{parallel} = 0.47(1) mu m and evidence is seen for a vortex decoupling transition in applied fields above 40 mT. The magnetic fluctuations in the normal state produce Korringa behavior of the muon spin relaxation rate below 100 K, a precipitous drop in relaxation rate is seen at higher temperatures and an enhanced local spin susceptibility occurs just above T_c.

6 pages, 4 figures

References in corpus (7)

• Unconventional critical behaviour in a quasi-two-dimensional organic conductor
• Strong electronic correlations in superconducting organic charge transfer salts
• Electron localization near Mott transition in organic superconductor $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2]$Br
• Universal scaling relations in molecular superconductors
• Superconductor-Insulator Phase Separation Induced by Rapid Cooling in kappa-(ET)_2Cu[N(CN)_2]Br
• Antiferromagnetic Spin Fluctuations in the Metallic Phase of Quasi-Two-Dimensional Organic Superconductors
• Phase separation in the vicinity of the surface of $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Br by fast cooling

Cited by in corpus (3)

• Odd-frequency pairing in (TMTSF)2ClO4
• Stretched exponential spin relaxation in organic superconductors
• Partially-ordered vortex lattices in the high-field, low-temperature mixed state of quasi two-dimensional organic superconductors