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Showing papers on "Colossal magnetoresistance published in 1988"


Journal ArticleDOI
TL;DR: In this article, a crossover between different contributions of magnetoresistance is investigated for high temperature superconductors above the critical point and the phase relaxation time and the theoretical formula of the crossover are discussed.
Abstract: Magnetoresistance for high temperature superconductors is investigated above the critical point. Near transition temperature, there is a crossover from two dimensions to three dimensions. According to superconducting fluctuation, a crossover between different contributions of magnetoresistance appears. The phase relaxation time and the theoretical formula of the crossover in the magnetoresistance are discussed.

188 citations


Journal ArticleDOI
TL;DR: Shubnikov-de Haas oscillations are observed in the low-temperature magnetoresistance of the organic metal )3"(BEDT-TTF)2AuBr2, which indicate the presence of small carrier pockets in the Fermi surface.
Abstract: Shubnikov-de Haas oscillations are observed in the low-temperature magnetoresistance of the organic metal )3\"(BEDT-TTF)2AuBr2, which indicate the presence of small carrier pockets in the Fermi surface. The nonoscillatory part of the magnetoresistance is highly anisotropic, and in one current direction an anomalously large negative magnetoresistance is observed. Some possible explanations for the negative magnetoresistance are considered, including an explanation based on magnetic-field-induced alignment of the carrier motion in the presence of scattering from internal boundaries.

24 citations


Journal ArticleDOI
15 Jun 1988-EPL
TL;DR: By measuring the structure, superconductivity, magnetoresistance of polycrystalline single-phase YBa2Cu3O7-δ samples, the phenomena of negative magnetore-sistance and the hysteresis of the magnetoreresistance have been studied as discussed by the authors.
Abstract: By measuring the structure, superconductivity, magnetoresistance of polycrystalline single-phase YBa2Cu3O7-δ samples, the phenomena of negative magnetoresistance and the hysteresis of the magnetoresistance have been studied. An analysis of the origin of the influence of grain boundaries on the superconductivity and the electronic transport properties are given.

21 citations


Journal ArticleDOI
TL;DR: The transverse magnetoresistance of the heavy-fermion superconductor UPt3 has been measured in a high quality single crystal as a function of magnetic field up to 28 T and of temperature down to 20 mK.

16 citations


Journal ArticleDOI
TL;DR: The spin-flip scattering of an electron by a pair of adjacent magnetic impurities is calculated in the presence of a magnetic field and yields an interesting field dependence for the magnetoresistance at various temperatures and may cause a change of sign in the magnetorsistance as well as in the Hall effect.
Abstract: The spin-flip scattering of an electron by a pair of adjacent magnetic impurities is calculated in the presence of a magnetic field. In the limit of zero field the pair scattering yields a sharp drop in the low-temperature resistivity whose strength is inversely proportional to T. This process provides an explanation for the anomalous drop in resistivity below T\ensuremath{\le}100 K for ${\mathrm{UPt}}_{3}$ and many other heavy-fermion alloys. An external magnetic field is shown to quench this spin-flip contribution, resulting in a positive magnetoresistance for ${\mathrm{UPt}}_{3}$ at low temperatures. In conjunction with the single-impurity Kondo scattering, the pair process yields an interesting field dependence for the magnetoresistance at various temperatures and may cause a change of sign in the magnetoresistance as well as in the Hall effect.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the effect of a magnetic field on the surface resistance of polycrystalline Cu at f = 1.2 GHz and at 4.4 K.
Abstract: We have measured the effect of a magnetic field on the surface resistance of polycrystalline Cu at f=1.2 GHz and at 4.4 K; under these conditions the surface resistance is well into the anomalous skin effect regime but has not reached its limiting value. We find that the transverse and longitudinal magnetoresistance are an order of magnitude smaller than the dc magnetoresistance and depend quadratically on the field. At low fields we observe a decrease in surface resistance with increasing field which can be interpreted as a size effect of the rf surface current, but is also typical of superconductors.

13 citations



Journal ArticleDOI
TL;DR: In this paper, the authors have studied both phases of GdB6 by experimental measurements of electrical resistivity, magnetoresistance, magnetic susceptibility, and Hall effect, and they have shown a large thermal hysteresis associated with the lower phase transition.
Abstract: Gadolinium hexaboride undergoes an antiferromagnetic phase transition below TN≂16 K. A second phase transition takes place below 11 K. We have studied both phases of GdB6 by experimental measurements of electrical resistivity, magnetoresistance, magnetic susceptibility, and Hall effect. The electrical resistivity data show a large thermal hysteresis associated with the lower‐phase transition. Magnetoresistance data in the higher phase is isotropic with respect to sample current and applied magnetic field directions. However, magnetoresistance measurements reveal some unusual behavior in the lower phase, namely, (i) the magnetoresistance is very anisotropic with respect to current and field directions, (ii) a large field hysteresis is observed, and (iii) a field‐induced transition is observed at 4.2 K in a field of ∼7 kOe. This field transition, which is also evident in magnetic susceptibility data, may be due to the formation of a single magnetic domain.

9 citations




Book ChapterDOI
TL;DR: The magnetic field dependence of microwave surface resistance of both single crystals and sintered polycrystals of YBa2Cu3O7-δ has been measured at 24 GHz as mentioned in this paper.
Abstract: The magnetic field dependence of microwave surface resistance of both single crystals and sintered polycrystals of YBa2Cu3O7-δ has been measured at 24 GHz. The resistance decreases below superconducting transition temperature and reaches constant residual resistance. The value is much lower for single crystals than for polycrystals. Furthermore polycrystals showed low field magnetoresistance and high field one with hysteresis which resembles the magnetization behavior of typical type II superconductor. The single crystal, however, showed nearly no magnetoresistance. The magnetoresistance observed is proved to be a inherent phenomena to sintered polycrystal which is composed of grains and contains many voids.