Quantum Monte Carlo study of the pairing symmetry competition in the Hubbard model

Abstract

To shed light into the pairing mechanism of possible spin-triplet superconductors (TMTSF)2X and Sr2RuO4, we study the competition among various spin singlet and triplet pairing channels in the Hubbard model by calculating the pairing interaction vertex using the ground state quantum Monte Carlo technique. We model (TMTSF)2X by a quarter-filled quasi-one dimensional (quasi-1D) Hubbard model, and the γ band of Sr2RuO4 by a two dimensional (2D) Hubbard model with a band filling of ∼ 4/3. For the quasi-1D system, we find that triplet f -wave pairing not only dominates over triplet p-wave in agreement with the spin fluctuation theory, but also looks unexpectedly competitive against d-wave. For the 2D system, although the results suggest presence of attractive interaction in the triplet pairing channels, the d-wave pairing interaction is found to be larger than those of the triplet channels.

Off-Site Repulsion-Induced Triplet Superconductivity: A Possibility for Chiralpx+y-Wave Pairing inSr2RuO4Arita1, Onari2, Kuroki3 et al. 2004Phys. Rev. Lett.Self Cite390370View full textAdd to dashboardCite

“…The result is consistent with Ref. [22], where d Now we move on to the extended Hubbard model in Fig.2, where the DCA+QMC result for the pairing susceptibility is plotted as a function of the off-site interaction V for T = 0.125 with the Trotter-Suzuki decomposition number L = 24. We can clearly see a qualitative tendency that p x+y and d xy become dominant with the introduction of V , while p x and d x 2 −y 2 are suppressed.…”

Pairing Symmetry Competition in Organic Superconductors

“…164 Namely, d xy is more favored when the dimerization is weaker, t b /t c is closer to unity (closer to isotropic triangular lattice), and the Fermi surface splitting is larger. These factors strongly depend on the anions.…”

“…140) because the nodes of the d xy gap do not intersect the Fermi surface, but the T c problem still exists even in that case. 164 In fact, Kondo and Moriya have studied the four band model using FLEX, and showed that a realistic T c can be obtained only when the dimerization is extremely strong (|t b1 /t b2 | > 5). 165 Such a strong dimerization indeed contradicts with the extended Hückel 119, 120 or the first principles calculations, 166,167 and also leads to the d x 2 −y 2 -wave pairing, which is not in agreement at least with the thermal conductivity 144 and the STM experiments 143 for X=Cu(NCS) 2 .…”

Triplet superconductivity in a 1D itinerant electron system with transverse spin anisotropy

“…This triggered interest in low-dimensional models of correlated electrons showing mechanism for Cooper pairing of triplet symmetry coexisting or closely competing with SDW type ordering. Although a wide variety of theoretical approaches have so far been used to study this topic [23,24,25,26,27,28,29], the understanding of the microscopic mechanisms for the complex phenomena in these compounds is still far from complete.…”