Impurity Effect on Superconducting Properties in Molecular Substituted Organic Superconductor κ-(ET)₂Cu(NCS)₂

Abstract

We report an impurity effect in the organic superconductor κ-(ET)2Cu(NCS)2 by substitution of the ET molecule with an analogue, bis(methyleneditio)tetrathiafulvalene (MT). The superconducting transition temperature decreases with increasing substitution. The in-plane magnetic penetration depth is enhanced with substitution, which is quantitatively attributed to the decrease in the in-plane mean free path. The enhancement of the penetration depth can also explain the reduction of the effective pinning in terms of the condensation energy.

Suppression of Superconductivity by Nonmagnetic Disorder in Organic Superconductor κ-(BEDT-TTF)2Cu(NCS)2

“…l is still larger than the in-plane coherence length ξ ≃ 5 -6 nm. 2,18 This condition of l ≫ ξ indicates that the superconductivity of the sample with the BMDT-TTF substitution should be in a clean limit.…”

Effects of Disorder on the Pressure-Induced Mott Transition in κ-(BEDT-TTF)2Cu[N(CN)2]Cl

“…Approaches to intentionally introduce disorder in a well-controlled manner in the κ-(BEDT-TTF) 2 X salts are manifold [42][43][44][45][46][47][48][49][50][51]. Among these, X-ray irradiation with typical irradiation times 0 h ≤ t irr ≤ 600 h has been widely used to control disorder in a non-reversible manner (see Ref.…”

“…For advancing our understanding in this field, materials which allow for a control of both the strength of correlations as well as the level of disorder are required. Both aspects are met favorably in the family of organic charge-transfer salts.Approaches to intentionally introduce disorder in a well-controlled manner in the κ-(BEDT-TTF) 2 X salts are manifold [42][43][44][45][46][47][48][49][50][51]. Among these, X-ray irradiation with typical irradiation times 0 h ≤ t irr ≤ 600 h has been widely used to control disorder in a non-reversible manner (see Ref.[48] for a review).…”

Mott-Anderson Transition in Molecular Conductors: Influence of Randomness on Strongly Correlated Electrons in the κ-(BEDT-TTF)2X System

“…There have been several investigations on the disorder effect in molecular conductors [18][19][20][21][22][23][24][25][26]. The disorder was introduced in many cases by controlling the sample cooling speed for changing the level of the conformational disorder of the terminal ethylene groups of BEDT-TTF [24][25][26] and in some cases by partial molecular substitution [21][22][23].…”

“…The disorder was introduced in many cases by controlling the sample cooling speed for changing the level of the conformational disorder of the terminal ethylene groups of BEDT-TTF [24][25][26] and in some cases by partial molecular substitution [21][22][23]. In addition, it is known that X-ray irradiation to the organic materials can cause molecular defects and disorder [18][19][20]27].…”