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Toward possibility of high-temperature bipolaronic superconductivity in boron tubular polymorph: Theoretical aspects of transition into anti-adiabatic state  [PDF]
P. Banacky,J. Noga,V. Sz?cs
Physics , 2012, DOI: 10.1016/j.jpcs.2012.04.001
Abstract: Large diameter single-wall boron nanotubes (SWBNT) produced by 2%Mg-mesoporous Al2O3 catalysis show diamagnetic transition at ~ 40 K and ~ 80 K, which is a serious indication for possible superconductivity (J.Phys.Chem.C113, (2009) 17661). Theoretical study which explains or disproves possibility of superconductivity in boron is so far absent, however. Here we apply first-principles formulation of nonadiabatic theory of electron-vibration interactions in study of band structure of boron nanotubes. The ab initio results show that electron-vibration coupling induces in SWBNT with diameter larger than 15 {\AA} transition into anti-adiabatic ground state at distorted-fluxional geometry. Thermodynamic and magnetic properties of anti-adiabatic ground state imply possibility of bipolaronic superconductivity. Calculated critical temperature Tc of large diameter SWBNT is 39 K and inclusion of Mg into a tube increases Tc up to 70-90 K. Presence of Al in SWBNT suppress superconductivity and a tube remains metallic down to 0 K. Superconducting properties could established boron nanotubes superior material for nanotechnology.


物理学报 , 1987,
Abstract: The effect of diagonal disorder on superconductivity of the triplet bipolaronic system with a two-delta random site energy distribution is analysed in the framework of the mean-field approximation. It is found that this kind of disorder strongly affects superconductivity of the system. When the triplet bipolaron concentration is near 1/2, the transition temperature decreased seriously; while when the concentration is small, the normal random site energy can not impede the occurence of superconductivity completely. This results from the tunneling motion of triplet bipolarons. It is therefore expected that superconductivity may appear in some amorphous semiconductors with low bipolaron concentration.
Reply to Comment on the paper "Pairing mechanism of high-temperature superconductivity: Experimental constraints (arXiv:1012.2368)"  [PDF]
Guo-meng Zhao
Physics , 2011, DOI: 10.1088/0031-8949/83/03/038304
Abstract: In our recent paper entitled "Pairing mechanism of high-temperature superconductivity: Experimental constraints" (to be published in Physica Scripta, arXiv:1012.2368), we review some crucial experiments that place strong constraints on the microscopic pairing mechanism of high-temperature superconductivity in cuprates. In particular, we show that phonons rather than spin-fluctuation play a predominant role in the microscopic pairing mechanism. We further show that the intrinsic pairing symmetry in the bulk is not d-wave, but extended s-wave (having eight line nodes) in hole-doped cuprates and nodeless s-wave in electron-doped cuprates. In contrast, the author of the Comment (to be published in Physica Scripta) argues that our conclusions are unconvincing and even misleading. In response to the criticisms in the Comment, we further show that our conclusions are well supported by experiments and his criticisms are lack of scientific ground.
Comment on "BCS superconductivity of Dirac fermions in graphene layers"  [PDF]
Bruno Uchoa,A. H. Castro Neto
Physics , 2009, DOI: 10.1103/PhysRevLett.102.109701
Abstract: Comment on "BCS superconductivity of Dirac fermions in graphene layers" by N. B. Kopnin and E. B. Sonin [arXiv:0803.3772; Phys. Rev. Lett. 100, 246808 (2008)].
Theoretical remark on the superconductivity of metals  [PDF]
Albert Einstein
Physics , 2005,
Abstract: In this paper Einstein develops some crucial ideas about superconductivity
Comment on "Can disorder really enhance superconductivity?"  [PDF]
I. M. Suslov
Physics , 2015,
Abstract: The paper by Mayoh and Garcia-Garcia [arXiv:1412.0029v1] is entitled "Can disorder really enhance superconductivity?". In our opinion, the answer given by the authors is not satisfactory, and we present the alternative picture. Our reply to the comment [arXiv:1502.06282] is added in the end, in order to reveal a series of untrue statements contained in it.
Comment on "Large energy gaps in CaC6 from tunneling spectroscopy: possible evidence of strong-coupling superconductivity"  [PDF]
N. Emery,C. Herold,S. Cahen,H. Rida,J. F. Mareche,P. Lagrange,G. Lamura
Physics , 2008,
Abstract: Comment on "Large energy gaps in CaC6 from tunneling spectroscopy: possible evidence of strong-coupling superconductivity"
Superconductivity of Magnesium Diboride: Theoretical Aspects  [PDF]
T. Dahm
Physics , 2004, DOI: 10.1007/3-540-27294-1_27
Abstract: In this work we review our present understanding of superconductivity in Magnesium Diboride from the theoretical perspective as it evolves from band structure calculations. Particular emphasis is placed on two gap superconductivity. Some of its peculiar consequences are discussed, in particular upper critical field anisotropy and microwave conductivity.
Theoretical Study on Coexistence of Ferromagnetism and Superconductivity  [PDF]
Hirono Kaneyasu,Kosaku Yamada
Physics , 2006, DOI: 10.1143/JPSJ.74.527
Abstract: On the basis of a two-dimensional t-t' Hubbard model in ferromagnetic and paramagnetic states, the triplet superconducting mechanism is investigated by the third-order perturbation theory with respect to the on-site Coulomb interaction U. In general, the superconducting state is more stable in the paramagnetic state than in the ferromagnetic state. As a special case, the dominant ferromagnetic superconductivity is obtained by the electron-electron correlation between the electronlike majority and holelike minority bands. Furthermore, it is pointed out that in some cases the two bands play an essential role for the coexistence of superconductivity and ferromagnetism.
Reply to comment by T. Terashima et al. on "Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe$_2$As$_2$"  [PDF]
J. K. Dong,S. Y. Zhou,T. Y. Guan,H. Zhang,Y. F. Dai,X. Qiu,X. F. Wang,Y. He,X. H. Chen,S. Y. Li
Physics , 2010,
Abstract: Reply to comment by T. Terashima et al. on "Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe$_2$As$_2$"
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