Observation of negative magnetoresistance in single crystal Y1−xPrxBa2Cu3O7−y

Pradhan, A. K.; Hazell, S.J.; Hodby, J.W.; Chen, C.; Chowdhury, A.J.S.; Wanklyn, B. M.

doi:10.1016/0038-1098(93)90632-w

Cited by 8 publications

(7 citation statements)

References 11 publications

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“…In particular, for H parallel to the c direction the ∆ρ (H) T saturation value is reached, at each temperature, for smaller field amplitudes than for H parallel to the ab planes. This behaviour of ∆ρ (T,H) is quite similar to that observed by other groups in other HTSC and LTSC compounds having ρ (T,H) peaks near the superconducting transition and attributed by these authors to intrinsic effects[29,[31][32][33][34][35] in particular, Figs. 7(a) and (b) with Fig.2of Ref.34).The experimental results for the Y16 sample after its reoxygenation are presented in Figs.8(a) and (b) for H applied parallel and, respectively, perpendicularly to the CuO 2 planes [see inset in Figs.6(a) and (b)].…”

supporting

confidence: 89%

“…It is now well established that the presence of T c -inhomogeneities at long length scales but non-uniformly distributed may generate various types of striking anomalies in the transport properties around the superconducting transition in HTSC, including the so-called anomalous peaks of the in-plane resistivity [25] the thermoelectric power [26] and the magnetoconductivity. [27,28] In addition to their intrinsic interest, these results may also provide an alternative explanation, in terms of temperature independent current redistributions associated with non uniformly distributed T c -inhomogeneities, of the anomalous resistivity and magnetoresistivity peaks observed above the average superconducting transition by different groups in other LTSC [29][30][31] and HTSC [32][33][34][35] compounds and that are being attributed to different, and in some cases not well settled, intrinsic effects. [29][30][31][32][33][34][35] In the case of the thermopower, it is also possible to explain the anomalous S(T) peaks observed in YBCO samples in terms of oxygen content inhomogeneities.…”

Section: T C -Inhomogeneities Non-uniformly Distributedmentioning

confidence: 99%

“…[27,28] In addition to their intrinsic interest, these results may also provide an alternative explanation, in terms of temperature independent current redistributions associated with non uniformly distributed T c -inhomogeneities, of the anomalous resistivity and magnetoresistivity peaks observed above the average superconducting transition by different groups in other LTSC [29][30][31] and HTSC [32][33][34][35] compounds and that are being attributed to different, and in some cases not well settled, intrinsic effects. [29][30][31][32][33][34][35] In the case of the thermopower, it is also possible to explain the anomalous S(T) peaks observed in YBCO samples in terms of oxygen content inhomogeneities. [26] In this case, this explanation does not need any particular distribution of the inhomogeneities but it needs the simultaneous presence of two possible consequences of these inhomogeneities [26]: differences between the T c ´s of various sample domains and also differences between the sign of their corresponding thermopower.…”

Section: T C -Inhomogeneities Non-uniformly Distributedmentioning

confidence: 99%

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On the Interplay Between T c -Inhomogeneities at Long Length Scales and Thermal Fluctuations Around the Average Superconducting Transition in Cuprates

Vidal

Veira

Maza

et al. 2001

High-Tc Superconductors and Related Materials

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We review at an introductory and pedagogical level some aspects of the interplay between inhomogeneities at long length scales (at length scales much bigger than any characteristic length for superconductivity, in particular than the superconducting coherence length amplitude, ξ (T), even at temperatures relatively close to T c ) and the intrinsic fluctuations of Cooper pairs above T c in high temperature cuprate superconductors (HTSC). These inhomogeneities at long length scales do not directly affect the thermal fluctuations, but they may deeply affect, together (and entangled!) with the thermal fluctuations, the measured behaviour of any observable around the transition. The emphasis is centered on the role played by the presence of T cinhomogeneities, as those associated with oxygen content inhomogeneities, at these long length scales and uniformly or non-uniformly distributed in the samples, on the inplane transport properties in inhomogeneous HTSC crystals. For completeness, we will also summarize some results on this interplay when various types of inhomogeneities (i.e., structural and stoichiometric, uniformly and non-uniformly distributed) may be simultaneously present.Thouless for LTSC´s: After having indicated that the observed rounding of ρ (T) around T c in their LaSCO compounds may be due to inhomogeneities, Bednorz and Müller concluded that "the onset (of the ρ (T) drop) can also be due to fluctuations in the superconducting wave functions". In fact, mainly due to the smallness of the superconducting coherence length amplitudes (at 0 K), ξ (0), which are anisotropic but in all directions of the order of the interatomic distances, both effects, those associated with the intrinsic thermal fluctuations and those with the extrinsic inhomogeneities, may be very important in the HTSC. This is mainly due, in the case of the thermal fluctuations, to the fact that a small ξ (T) leads to a small coherent volume, which will contain very few strongly correlated Cooper pairs. These fluctuation effects are also enhanced by the layered nature of the HTSC, which may lead these materials to behave as quasi bi-dimensional superconductors (still reducing, then, their superconducting coherent volume) and their high T c , which increase then the available (gratis!) thermal agitation energy, of the order of k B T c (where k B is the Boltzmann constant) around their superconducting transition. [3] In the case of the inhomogeneities, the smallness of ξ (T) makes the different superconducting properties of these materials very sensitive to the presence of inhomogeneities, even when they have very small characteristic length, of the order of ξ (T). In addition, their layered nature and the complexity of their chemistry enhance the probability of the presence of extrinsic inhomogeneity effects in real HTSC compounds. When they are present at long length scales (i.e., at length scales much bigger than any characteristic length in the system, as the magnetic field penetration length or, mainly, the superconducting coherence le...

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supporting

confidence: 89%

Section: T C -Inhomogeneities Non-uniformly Distributedmentioning

confidence: 99%

Section: T C -Inhomogeneities Non-uniformly Distributedmentioning

confidence: 99%

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On the Interplay Between T c -Inhomogeneities at Long Length Scales and Thermal Fluctuations Around the Average Superconducting Transition in Cuprates

Vidal

Veira

Maza

et al. 2001

High-Tc Superconductors and Related Materials

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“…Consequently, the decrease of T c with increasing x obtained in Y 1−x Pr x BCO is most likely due to localization of the charge carriers as the Pr concentration is increased. 10,11 In turn, the observed increase of ͑T͒ in YPrBCO can be adjudged to be one of the factors explaining the lowering of T * in YPrBCO with increasing Pr concentration.…”

Section: Resultsmentioning

confidence: 94%

“…9,10 Therefore, doping with Pr does not alter the crystal structure of the sample, so it is possible to study the properties of a HTSC directly upon variation of n f . Studies have been done on YPrBCO polycrystals, 9 single crystals, 10,11 and thin films. 12 Recently much attention has been paid to the investigation of various properties of YPrBCO-PrBCO superlattices.…”

Section: Introductionmentioning

confidence: 99%

Fluctuation conductivity and pseudogap in Y1−xPrxBa2Cu3O7−y films

Solovjov

Dmitriev

2006

Low Temperature Physics

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The fluctuation conductivity (FC) and pseudogap (PG) in Y1−xPrxBa2Cu3O7−y with x≈0.1 are investigated. It is shown that the temperature dependence of the FC is the same as in YBa2Cu3O7−y containing defects. At the same time, the temperature dependence of the PG differs from the analogous dependence obtained for YBa2Cu3O7−y films. An increase of the coherence length and decrease of the characteristic temperature T* in Y1−xPrxBa2Cu3O7−y is observed with increasing Pr concentration.

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