Comparison of the normal-state properties of -(BEDT-TTF)2Cu(NCS)2and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Biggs, Tim; Klehe, A.-K.; Singleton, John; Bakker, David; Symington, J. A.; Goddard, Paul; Ardavan, Arzhang; Hayes, W.; Schlueter, John A.; Sasaki, Takehiko; Kurmoo, Mohamedally

doi:10.1088/0953-8984/14/26/102

Cited by 27 publications

(81 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2, where the area is constrained by F α from the SdH data The semi-major and minor axes of the α pocket obtained in this manner are 2.2 ± 0.2 nm −1 and 1.06 ± 0.09 nm −1 respectively. Therefore, in good quantitative agreement with earlier work [18,27], we find the effect of increased pressure is to make the α pocket less elongated.…”

supporting

confidence: 92%

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

et al. 2007

View full text Add to dashboard Cite

We present experimental evidence for a hitherto unconfirmed type of angle-dependent magnetoresistance oscillation caused by magnetic breakdown. The effect was observed in the organic superconductor κ-(BEDT-TTF)2Cu(NCS)2 using hydrostatic pressures of up to 9.8 kbar and magnetic fields of up to 33 T. In addition, we show that similar oscillations are revealed in ambient pressure measurements, provided that the Shubnikov-de Haas oscillations are suppressed either by elevated temperatures or filtering of the data. These results provide a compelling validation of Pippard's semiclassical picture of magnetic breakdown.

show abstract

supporting

confidence: 92%

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Actually, our data are consistent with a granular interpretation where the macroscopic radius R must be substituted by some average cluster radius r. Moreover, the topology of the clusters can be described by a percolation model 20 At this point, it may seem surprising that we did not refer to the Mott-Hubbard model 25,26 , which is known to describe some fundamental properties of organic conductors. This is particularly true for the influence of pressure on various physical parameters 25,27,28 . However, the situation seems to be much more complicated concerning the kind of measurements reported here, even though these measurements are probably connected somehow to the Mott- …”

mentioning

confidence: 99%

Interplay between the glassy transition and granular superconductivity in organic materials

et al. 2006

View full text Add to dashboard Cite

It is known that some (BEDT-TTF) 2 X layered organic superconductors undergo a glassy transition near 80 K. Our purpose is to exploit quenched disorder to get new insights on both the superconducting state (T ≤ 12 K) and the glassy transition by studying the superconducting properties as functions of annealing time (t a ) and temperature (T a 1) The data can be described by a percolation cluster model. 2) At short time scales, the clusters grow with t a following a power law. 3) At large time scales the clusters grow toward a thermodynamic state following a stretched exponential law However, we emphasize that the low-temperature state contains some amount of quenched disorder that strongly depends on the anion, the applied pressure, the cooling conditions and, more importantly, on whether the ethylene groups are formed by hydrogen bonds (denoted H8-Br) or deuterium bonds (denoted D8-Br). This is why the exact nature of the 80 K anomaly and the associated low-temperature superconducting state are still not understood.)As a matter of fact, D8-Br exhibits several puzzling superconducting properties. Some of these properties were ascribed to the appearance of a magnetic transition at low temperature (10-20 K), the meaning of which is unclear: Several mechanisms have been proposed including spin-density waves 13 , spin canting 12 , or the suppression of superconductivity by dispersed magnetic ions associated with the persistent disorder 14 . Also, some authors 7,8 3 ascribed the decrease of the apparent superconducting volume to an increase in λ (the inplane penetration depth) through mean-free-path effect 7 .However none of these mechanisms is able to explain, even qualitatively, the following experimental facts: 1) The fact that the apparent magnetic critical current density j c (as deduced from the Bean model) always decreases as the degree of quenched disorder increases.2) The low-field susceptibility also decreases in the same experimental conditions.To account for such a decrease, one is led to assume that λ can reach unphysical values, as high as 0.1 mm [8] (and much more if applied to the present results). 3) Despite these large changes in the apparent j c and λ , T c stays almost constant. 4) As the quenched disorder is increased; one observes: firstly, the appearance of increasing irreversibilities at H << H c1 (for instance, H = 0.1 Oe and T = 2 K), secondly, a large broadening of the superconducting transition.One of the purposes of this work is to prove that all of these features can naturally be explained in the framework of a granular model and the associated weak links connecting the grains.We have investigated the ac magnetic susceptibility and the dc magnetization of the superconducting phase after performing a series of thermal treatments on a D8-Br singlecrystal of dimension ~ 1 × 1 × 0.25 mm 3 . To this end, we annealed the sample inside the SQUID cryostat at different fixed temperatures T a ranging from 65 to 110 K. Moreover, in order to carefully monitor the development of ethylene or...

show abstract

“…The pressure dependence of T c in κ-(BEDT-TTF) 2 Cu(SCN) 2 , however, is not affected by the isotope composition [25], as was determined in ac-susceptibility measurements where helium was used as a pressure medium for all samples. The latter result highlights that the difference in pressure dependence upon deuteration seen in [15] does not originate in the isotope composition, but that other experimental factors, such as the choice of pressure medium, might be relevant.…”

Section: Introductionmentioning

confidence: 88%

“…The observed increase of the Q2D Fermi surface area under pressure [15,20,21] as well as under uniaxial stress in the out-of-plane direction [18], is thought to originate from a pressure-induced intradimer sliding motion [19].…”

Section: Introductionmentioning

confidence: 98%

“…This pressure induced increase is currently considered to be the driving force of the different pressure-induced phase transitions observed in κ-(BEDT-TTF) 2 Cu(SCN) 2 [14]. Recent studies [13,15] have also discussed and investigated the importance of the out-of plane direction, the crystallographic a ′ -direction perpendicular to the bc-plane, for a more general understanding of the general physical properties of κ-(BEDT-TTF) 2 Cu(SCN) 2 . The interlayer transfer integral, t ⊥ ≈ 0.04 meV, was found to be a factor ≤ 10 3 smaller than that observed for the intralayer components, t b and t c [13], indicating that κ-(BEDT-TTF) 2 Cu(SCN) 2 is predominantly Q2D in its electronic properties, even though there is a small degree of coherent interlayer transport [13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Klehe¹,

Biggs²,

Kuntscher³

et al. 2004

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract.We compare magnetotransport measurements under pressure on the organic superconductor κ-(BEDT-TTF) 2 Cu(SCN) 2 with different pressure-media and discover that the results are pressure media dependent. This pressure-medium dependence is thought to originate from the difference in thermal contraction between the very soft and highly anisotropic sample and the isotropically contracting, but solid pressure medium, thus resulting in non-hydrostatic pressure on the sample. However, comparison of pressure measurements with different media reveals a pressure-medium independent correlation between the superconducting transition temperature, Tc, and the size of the quasi 2-dimensional Fermi surface pocket and thus the quasi 2-dimensional carrier density in κ-(BEDT-TTF) 2 Cu(SCN) 2 . The observed pressure-induced increase in the quasi 2-dimensional carrier density can be interpreted as a transfer of carriers from quasi 1-dimensional Fermi surface sections, reminiscent of a mechanism in cuprate superconductors, where pressure is known to transfer carriers from the insulating charge reservoir layers into the conducting cuprate sheets.

show abstract

Comparison of the normal-state properties of -(BEDT-TTF)₂Cu(NCS)₂and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Cited by 27 publications

References 44 publications

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

Interplay between the glassy transition and granular superconductivity in organic materials

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Contact Info

Product

Resources

About

Comparison of the normal-state properties of -(BEDT-TTF)2Cu(NCS)2and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Cited by 27 publications

References 44 publications

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

Angle-dependent magnetoresistance oscillations due to magnetic breakdown orbits

Interplay between the glassy transition and granular superconductivity in organic materials

Comparative magnetotransport andTcmeasurements on -(BEDT-TTF)2Cu(SCN)2under pressure

Contact Info

Product

Resources

About

Comparison of the normal-state properties of -(BEDT-TTF)₂Cu(NCS)₂and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure