Mössbauer study of the La2−xSrxNi0.99Fe0.01O4±δ system

Phase separation in the vicinity of the surface ofκ−(BEDT−TTF)2Cu[N(CN

“…A remarkable difference in λ (0) between the two groups appears for fast cooling, especially for X = Cu[N(CN) 2 ]Br. In ac susceptibility measurements 4 in magnetic fields lower than H c1 , λ (0) is 24-100 µm, which is two or three orders of magnitude larger than that obtained from magnetization measurements 14,15 in magnetic fields higher than H c1 , ∼ 0.7 µm. The former value of λ (0) is quite large as a characteristic parameter of superconductivity and is likely to be an overestimate.…”

“…The disorder in the SC region gives impurity scattering. The increase of the Dingle temperature 34 and the slight increase of λ (0) observed in the high field measurements 14,15 can be explained as the influence of quasi-particle scattering by the increase of disorder in the fast cooling process. Meanwhile, a decrease of T c , 14,15,21,30 vortex pinning suppression, 29 and an increase of the residual resistivity 30 may result from both the contributions of microscopic impurity scattering and macroscopic insulating region (or boundary) formation by fast cooling.…”

“…There have been many previous studies on the in-plane penetration depth λ of the quasi-twodimensional organic superconductors κ-(BEDT- 19,22 TTF) 2 X [X=Cu(NCS) 2 or Cu[N(CN) 2 ]Br; BEDT-TTF: bis(ethylenedithio)-tetrathiafulvalene, also written as ET], by ac susceptibility, 1,2,3,4 surface impedance, 5,6 ac inductance 7 , µSR, 8,9,10,11 magnetization, 12,13,14,15 etc. In spite of these efforts, the temperature dependence of λ and the absolute value of λ (0) are still unknown or controversial.…”

Superconductor-insulator phase separation induced by rapid cooling ofκ−(BEDT−TTF)2Cu[N(CN)2Taylor1, Carrington2, Schlueter3 2008Phys. Rev. B252280View full textAdd to dashboardCite

“…This reduction in γ is consistent with the reduction in su- perconducting volume fraction (or decrease in superfluid density) observed in magnetization measurements. 12 By subtracting the 14T normal state data from the zero field data the superconducting anomaly at T c is clearly discernable (see Fig. 3).…”

“…10 Magnetization measurements have shown that fast cooling also causes a marked decrease in the magnetic screening which was interpreted as either a decrease in the superconducting volume fraction or an increase in the magnetic penetration depth λ. 12 Scanning microregion infrared reflectance spectroscopy (SMIRS) measurements 13 have shown evidence for macroscopic insulating/metallic region phase separation at the surface of fast cooled samples. In deuterated κ-Br 13 C-NMR 14 and magnetoresistance measurements 7 show evidence for phase separation even in slowly cooled samples.…”