Tc and deltao in a phenomenological ''pseudogap'' model

Romero, D. B.; Sánchez, Lissette Jiménez; Rodríguez-Núñez, J. J.; Beck, H. P.

doi:10.1590/s0103-97332003000400023

Cited by 2 publications

(1 citation statement)

References 14 publications

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“…The present paper began with the initial participation of D Romero and L Sánchez, who after some time left the group. The interpretation given here is completely new (see [61]) and the numerical calculations presented here resulted from computer calculations performed at LANA, Universidade Federal de Santa Maria, Brazil. These calculations were carried out in a cluster of 16 CPUs.…”

Section: Discussionmentioning

confidence: 91%

The effect of a pseudogap on the superconducting critical temperature and on the superconducting order parameter of the same symmetry

Rodríguez-Núñez¹,

Schmidt²,

Beck³

2005

J. Phys.: Condens. Matter

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We study numerically the superconductivity in a system whose normal state is characterized by the presence of a phenomenological pseudogap, Eg/t, in the energy spectrum, for . T* is called the crossover temperature and it is defined in the high-temperature superconductors (HTSC) where the static spin susceptibility, χ(T), is a maximum. At T* one also observes the formation of a pseudogap in the density of states around the chemical potential (Maier et al 2002 Preprint cond-mat/0208419). In order to fix ideas, we have chosen the pseudogap and the superconducting gap to have the same symmetry. We have adopted the scenario where the pseudogap and the superconducting gap are independent of each other (Tallon and Loram 2001 Physica C 349 53), for which the pseudogap enters in the superconducting phase going down to zero at zero temperature. We have found that we require a critical value of the superconducting interaction, V/t, to produce a finite superconducting critical temperature, Tc/t, and the superconductor order parameter at T/t = 0, Δ0/t. These results have been obtained for both μ/t = 0 and . We have obtained a phase diagram, namely, V/t versus Eg/t, at half-filling. We have compared our results with the analytical calculations of Ţifrea et al (2002 Physica C 371 104), the recent work of Ţifrea and Moca (2003 Preprint cond-mat/0307362 (2004 Europhys. J. B, at press)) and other relevant theoretical results.

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Section: Discussionmentioning

confidence: 91%

The effect of a pseudogap on the superconducting critical temperature and on the superconducting order parameter of the same symmetry

Rodríguez-Núñez¹,

Schmidt²,

Beck³

2005

J. Phys.: Condens. Matter

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The BCS–BE crossover phase diagram atT= 0 K for a d-wave superconductor: the importance of the Debye frequency and the tight binding band structure

Rodríguez-Núñez

Schmidt

Alvarez-Llamoza

et al. 2004

J. Phys.: Condens. Matter

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We consider the phase diagram of the BCS (Bardeen–Cooper–Schrieffer)–BE (Bose–Einstein) crossover in the ground state (T = 0 K) of a dx2−y2-wave superconductor, with a nearest neighbour tight binding structure, when we take into account the Debye (phononic) frequency around the chemical potential, μ. This approach is a continuation of the work of den Hertog (1999 Phys. Rev. B 60 559) and that of Soares et al (2002 Phys. Rev. B 65 174506). The latter authors considered the influence of the second-nearest neighbours, but neither set of authors took into account the effect of the Debye frequency, ωD, or the influence of the next nearest neighbour matrix hopping element. We have found the following results: (1) there is not a metallic phase—that is, when , , , and , where n is the carrier density per site, V is the attractive interaction, t is the nearest neighbour hopping integral, and is the next nearest neighbour hopping ratio; (2) the BCS–BE crossover line is strongly affected by the presence of ωD/4t and that of —actually, the values of V/4t needed to achieve the Bose–Einstein regime become extremely large for small values of ωD/4t; and (3) both Δ/4t and μ/4t strongly depend on the values of ωD/4t and . The results (1) are in agreement with the ones found by Perali et al (2003 Phys. Rev. B 68 066501 (Preprint cond-mat/0211132)) and Rodríguez-Núñez et al (2003 Phys. Rev. B 68 066502), and in disagreement with those of den Hertog and Soares et al.

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Tc and deltao in a phenomenological ''pseudogap'' model

Cited by 2 publications

References 14 publications

The effect of a pseudogap on the superconducting critical temperature and on the superconducting order parameter of the same symmetry

The effect of a pseudogap on the superconducting critical temperature and on the superconducting order parameter of the same symmetry

The BCS–BE crossover phase diagram atT= 0 K for a d-wave superconductor: the importance of the Debye frequency and the tight binding band structure

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