Topic
High-temperature superconductivity
About: High-temperature superconductivity is a research topic. Over the lifetime, 7263 publications have been published within this topic receiving 175377 citations. The topic is also known as: high-temperature superconductivity.
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TL;DR: It is found that gamma_{sc} has a humplike anomaly at T_{c} and behaves as a long tail which persists far into the normal state for the underdoped samples, but for the heavily overdoped samples the anomaly ends sharply just near T_{ c}.
Abstract: We have measured the magnetic field and temperature dependence of specific heat on Bi2Sr2� xLaxCuO6þ� single crystals in wide doping and temperature regions. The superconductivity related specific-heat coefficientsc and entropy Ssc are determined. It is found thatsc has a humplike anomaly at Tc and behaves as a long tail which persists far into the normal state for the underdoped samples, but for the heavily overdoped samples the anomaly ends sharply just near Tc. Interestingly, we found that the entropy associated with superconductivity is roughly conserved when and only when the long tail part in the normal state is taken into account for the underdoped samples, indicating the residual superconductivity above Tc.
45 citations
TL;DR: The high-frequency vortex dynamics of high-temperature superconductors near the flux-line depinning threshold is investigated based on a thermally activated flux-flow (TAFF) model and is found qualitatively consistent.
Abstract: The high-frequency vortex dynamics of high-temperature superconductors near the flux-line depinning threshold is investigated based on a thermally activated flux-flow (TAFF) model. Dissipation due to vortex motion driven by a microwave electromagnetic field is studied as a function of the frequency, temperature, dc magnetic field, and microwave power. The generalized TAFF model is also compared to the conventional flux-creep theory and is found qualitatively consistent.
45 citations
TL;DR: In this article, a face-to-face type superconducting bulk magnet system was applied to the high gradient magnetic separation (HGMS) in which a pair of bulk superconductors were oppositely arranged, and a magnetic field of 1.6 T was achieved between the magnetic poles.
Abstract: Our research is to magnetize the high-T/sub c/ bulk superconductors and to supply magnetic field environment realized by superconducting bulk magnets to various applications. In this paper, we aim to apply the superconducting bulk magnets to the high gradient magnetic separation (HGMS). Using a face-to-face type superconducting bulk magnet system in which a pair of bulk superconductors are oppositely arranged, Y123 bulk superconductors are magnetized by the "IMRA" method (pulsed field magnetization), and consequently, a magnetic field of 1.6 T is achieved between the magnetic poles. Next, HGMS using superconducting bulk magnets is demonstrated. A separation pipe into which filter matrices composed by ferromagnetic wires are stuffed is set between the magnetic poles and the slurry mixed with fine powder of /spl alpha/-hematite (Fe/sub 2/O/sub 3/) particles is flown. As the results of HGMS, over 90% of the Fe/sub 2/O/sub 3/ was separated. Moreover, separation filters have to be washed so that they are not clogged with captured particles. We confirmed that the filter was briefly washed by flowing water after moving the separation pipe from magnetic poles.
44 citations
TL;DR: The Wohlleben effect was first observed in the field-cooled regime of high-Tc superconductors as mentioned in this paper, where the magnetic response of some HTSC at very low fields (≲ 1Oe) becomes paramagnetic.
Abstract: Recently a quite unexpected phenomenon was observed during the study of the magnetic properties of High-Tc superconductors: In the field-cooled regime the magnetic response of some HTSC at very low fields (≲ 1Oe), instead of being diamagnetic, becomes paramagnetic. Such behavior is perfectly reproducible and stable. This effect is now called the Wohlleben Effect. The samples showing the Wohlleben effect also display anomalous behavior in some other properties (microwave absorption, second harmonic of magnetic susceptibility). In this paper a survey is given of the experimental studies of this and related phenomena, carried out in different laboratories. Corresponding theoretical models are also discussed. The effect is attributed to the formation of spontaneous currents (spontaneous orbital magnetic moments) in the ground state of the weak link network in case when Josephson coupling between certain grains is negative (π-contacts). Microscopic mechanisms of inverse Josephson coupling are discussed especially in connection with the possible unconventional pairing in HTSC.
44 citations