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An extension of the Bardeen-Cooper-Schrieffer model of superconductivity

机译:Bardeen-Cooper-Schrieffer超导模型的扩展

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An extension of the BCS Hamiltonian of H-BCS the form H = H-BCS + W + V, where W = Sigma k gamma knk = nk -, V = -Lambda(-1) X Sigma(k,k')g(k,k')b(k)*b*(-k)b(-k')b(k'), n(k sigma) = a(k sigma)* a(k sigma), b(k) = a(k) (+) a(k) are fermion creation and annihilation operators, is investigated. It is shown that H represents a solvable mean-field model in the thermodynamic limit. H exhibits a 2nd-order phase transition if W is sufficiently strongly attractive and the low-temperature phase, characterized by two order parameters, contains two Condensates: a condensate of BCS-type fermion pairs and a condensate of fermion quadruples with momenta and spins (p,sigma) equal {(p,sigma),(- p,sigma), (p,- sigma), (- p, - sigma)}. If gamma(k), < 0, a pseudogap is present in the excitation spectrum in the normal phase. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 34]
机译:H-BCS的BCS哈密顿量的扩展形式为H = H-BCS + W + V,其中W = Sigma kγknk = nk-,V =- Lambda (-1)X Sigma(k,k' )g(k,k')b(k)* b *(-k)b(-k')b(k'),n(k sigma)= a(k sigma)* a(k sigma),b (k)= a(k)(+)a(k)是费米子生成和an灭算符的研究对象。结果表明,H代表热力学极限中的可解平均场模型。如果W具有足够强的吸引力,则H表现出二阶相变,并且以两个阶数参数为特征的低温相包含两个冷凝物:BCS型费米对的冷凝物和带有动量和自旋的四重费米子的冷凝物( p,sigma)等于{(p,sigma),(-p,sigma),(p,-sigma),(-p,-sigma)}。如果gamma(k)<0,则正常相位的激发光谱中存在伪间隙。 (C)2000 Elsevier Science B.V.保留所有权利。 [参考:34]

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