Explaining various theories of superconductivity, superconductors and their applications

• Liu Ying

  How to electrodeposited graphene in a aquesous soultion?

  Help!
• Tanguy Damart

  What is the easiest way to synthesize K3C60?

  I am undergraduate and I try to show that the K3C60 is a superconductor. For my experiment I have access to a glove box, an evacuation/Schlenk line, SQUID and XRD. I have C60 99.0%, C60 99.9% andI am undergraduate and I try to show that the K3C60 is a superconductor. For my experiment I have access to a glove box, an evacuation/Schlenk line, SQUID and XRD. I have C60 99.0%, C60 99.9% and K. My final product don't have to be perfect, just good enought to show that K3C60 is a superconductor.
• Nashiruddin Ahammed

  Is there any diffferences between temperature vs resistivity curve of type1 and type2 superconductor?

  Is there any diffferences between temperature vs resistivity curve of type1 and type2 superconductor?

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    Phillip Broussard replied

    What region of temperature are you interested in? Nb (type II) and YBCO (type II) have very different rho vs T behavior. So there is no necessary correlation between the resistivity vs T curve andWhat region of temperature are you interested in? Nb (type II) and YBCO (type II) have very different rho vs T behavior. So there is no necessary correlation between the resistivity vs T curve and what type superconductor it is.

    3 days ago
• Gayatri Keskar

  What could be the different mechanisms responsible for diamagnetic transition apart from superconductivity?

  I am working on nanostructured bismuth chalcogenides and I see diamagnetic transition in M vs T curve however, I do not see zero resistance ruling out superconductivity. I would like to know whatI am working on nanostructured bismuth chalcogenides and I see diamagnetic transition in M vs T curve however, I do not see zero resistance ruling out superconductivity. I would like to know what other mechanisms can lead to such behavior?

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    Sanjay Sood replied

    Diamagnetic transition also implies generation of surface currents. The magnetic field associated with these currents would expel the external magnetic field. This phenomenon would like very muchDiamagnetic transition also implies generation of surface currents. The magnetic field associated with these currents would expel the external magnetic field. This phenomenon would like very much like the superconducting transition, but in this case the resistivity would not vanish as you have seen in your measurements.

    3 days ago
• Rajeswari Subramaniam

  I would like to know is anyone is working on "High temperature Superconductors for the application of Power devices"?

  High Temperature Superconductors
• Tian De Cao

  respond

  1. as the temperature rises, superconductivity disappears, and high-Tc superconductivity is not mediated by phonons; 2. "magnetism mediated superconductivity" should be corrected as "magnetic1. as the temperature rises, superconductivity disappears, and high-Tc superconductivity is not mediated by phonons; 2. "magnetism mediated superconductivity" should be corrected as "magnetic fluctuations mediated superconductivity".

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    Viorel Sandu replied

    No, there is no direct relationship. Normal state resistivity is related to the mechanisms of scattering of the charge carriers. Of course, the peculiarities of the scattering might be related toNo, there is no direct relationship. Normal state resistivity is related to the mechanisms of scattering of the charge carriers. Of course, the peculiarities of the scattering might be related to the mechanisms leading to the pairing. Different classes of superconductors shows different T dependence, but this belong to the class of materials and not to the type of superconductors. However, Kosterlitz-Thouless transition and the associated resistivity tail is typical only for type 2 superconductors.

    4 days ago
• Labao Zhang

  Why can't the SSPD (SNSPD) resolve the energy and number of photons during a detection event?

  For a traditional SSPD, we only observed a voltage pulse regardless of the photon number in a laser pulse. In BCS theory, the enery gap is around several meV. A photon can break hundreds of CooperFor a traditional SSPD, we only observed a voltage pulse regardless of the photon number in a laser pulse. In BCS theory, the enery gap is around several meV. A photon can break hundreds of Cooper pairs, even more. But in our experiment, the efficiency (detection probability) is dropped in IR photons band and the output signal also can't distinguish the photon energy and number.

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    Stefan Mehedinteanu replied

    Dear Zhang, My paper is ready to be published in Journal of Nuclear particle and Physics (Scientific& Academic PUblishing, USA) an oppen source journal. Paper Title: ON THE PHOTONUCLEAR RATESDear Zhang, My paper is ready to be published in Journal of Nuclear particle and Physics (Scientific& Academic PUblishing, USA) an oppen source journal. Paper Title: ON THE PHOTONUCLEAR RATES CALCULATION FOR NUCLEAR TRANSMUTATION OF BETA DECAY NUCLIDES BY APPLICATION OF THE GINZBURG-LANDAU THEORY has been accepted for the publication. It will be published in Journal of Nuclear and Particle Physics (Vol.2, No.3, June 2012) . Even the paper subject reffers to transmutation, here is given a lot of details about the method and refference to the superconductors (nanwires), very ussefully for you, anyhow I can help ypu to understand better the paper! Stefan Mehedinteanu

    7 days ago
• Anup Pattanaik

  What is vortex overlapping mechanism in the phenomenon of superconductivity?

  Vortex overlapping or overlapping of vortices in the theory of high temperature superconductivity.

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    Stefan Mehedinteanu replied

    Is the interaction between vortex lines.

    24 days ago
• naveen h Gouda

  superconductvity

  is it have the fermi energy

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    Tian De Cao replied

    Vanish? But the Fermi surface can be still defined and observed.

    Apr 4, 2012
• Srikrishna R N

  I am designing a high temperature superconducting dc motor prototype. Can anyone pl share more technical details and experience on this project?

  By technical details, i mean rotor size, stator size and placing, cooling arrangement, current leads used, the performance graphs, support material for rotor and stator and such technical data

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    Srikrishna R N replied

    @Jess: OK OK.. Anyways, thanks for the suggestions and the lecture.

    Feb 6, 2012
• Rob Woudenberg

  I noticed this internet publication on room temperature superconductivity : http://www.superconductors.org/28c_rtsc.htm Any comments?

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• Tian De Cao

  My predictions confirmed by experiments (1): discovery of iron-based superconductors

  In February 2008, Hideo Hosono and co-workers reported the discovery of 26 K superconductivity in fluorine-doped LaFeAsO [1], which is said to be completely unexpected, because elemental iron is In February 2008, Hideo Hosono and co-workers reported the discovery of 26 K superconductivity in fluorine-doped LaFeAsO [1], which is said to be completely unexpected, because elemental iron is strongly magnetic and magnetic elements seem to be unbeneficial to superconductivity. However, in 2007, Tian De Cao discussed how to change a magnetic material into a superconductor [2]. In that article I write: “SCM in normal states usually are magnetic materials. To turn them into superconductors, we have to strengthen the charge correlations or weaken the spin correlations in them. One, by substituting non-magnetic elements for some magnetic elements in them, because the changes of the charge correlation with disorders are not monotonous, when the effects of charge correlations overcome the effects of disorders, they become superconductors. Two, by doping, like the cases in the p-type cuprate superconductors. Three, by extra influences, usual way to increase the charge correlation is to increase pressures. There are other ways.” 1. Kamihara, Y., Watanabe, T., Hirano, M. & Hosono, H. Iron-Based Layered Superconductor La[O1-xFx]FeAs (x = 0.05-0.12) with Tc = 26 K. J. Am. Chem. Soc. 130, 3296 (2008). 2. Tian De Cao, arXiv:0707.3660v2&3

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    Tian De Cao replied

    if a no-magnetic material is doped with magnetic nano-particles, its low temperature resitivity is usually increased. By accident, non-superconducting material becomes superconducting one (at lowif a no-magnetic material is doped with magnetic nano-particles, its low temperature resitivity is usually increased. By accident, non-superconducting material becomes superconducting one (at low temperature).

    Nov 30, 2011
• Zhang Han

  Synthesis and crystal growth of Cs(0.8)(FeSe(0.98))(2): a new iron-based superconductor with T(c) = 27 K.A Krzton-Maziopa, Z Shermadini, E Pomjakushina, V Pomjakushin, M Bendele, A Amato, R Khasanov, H Luetkens, K Conder
• Tian De Cao

  My basic ideas of superconducting mechanism

  First, the superconductivity requires the pairing between electrons (holes). This is consistent with the one of other physicists, and it is not a new one. Second, the superconductivity requires andFirst, the superconductivity requires the pairing between electrons (holes). This is consistent with the one of other physicists, and it is not a new one. Second, the superconductivity requires and only requires the pairs on and around the Fermi surface. This is a viewpoint following the BCS theory, and I have extended it to various superconductivity. Third, if the pairs are far from the Fermi surface, the pseudogap state occurs in the material. The preformed pairs have been suggested by other physicists, but the relation between the superconductivity, the pseudogap state and the preformed pairs has been an open question. Fourth, the pairs should originate from the affective electron-electron interaction renormlized by other factors. This is to say, various factors (phonon, impurity, crystal structure, …) may be responsible for the superconductivity. The viewpoints above could be found in my papers on arXiv or journals.

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    Sidney Clouston replied

    Superfluidity? http://www.egglescliffe.org.uk/physics/supercond/supfluid/superfluids.html

    Sep 14, 2011
• Tian De Cao

  Possible josephson effect in room temperature

  We suggest that both the pseudogaps and the band gaps occur at each antinodal region of cuprate superconductors when T<T*(Cao Tian-De, Chin.Phys.B19(11),117401, 2010.), the pseudogap could lead toWe suggest that both the pseudogaps and the band gaps occur at each antinodal region of cuprate superconductors when T<T*(Cao Tian-De, Chin.Phys.B19(11),117401, 2010.), the pseudogap could lead to the Josephson effect of two superconductors in or near room temperature, and this may be an important progress as soon as this prediction will be confirmed.

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    Tian De Cao replied

    The "band gap" may be from some orders, such as the spin denxity wave state, they are around the Fermi surface.

    Mar 10, 2011