Momentum dependence of pseudogap and superconducting gap in variation theory |
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Authors: | T Watanabe H Yokoyama M Ogata |
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Institution: | aInstitute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan;bDepartment of Physics, Tohoku University, Aramaki-aza-aoba 6-3, Aoba-ku, Sendai 980-8578, Japan;cDepartment of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan |
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Abstract: | To consider the origin of a pseudogap and a superconducting (SC) gap found in the high-Tc cuprates, we evaluated the momentum dependence of the singlet gap corresponding to the pseudogap and the SC gap in the t–J model, using an optimization variational Monte Carlo (VMC) method. In the underdoped regime, the singlet gap is significantly modified from the simple dx2-y2(d)-wave gap (∝ cos kx − cos ky) by the contribution of long-range pairings. Its angular dependence at the quasi Fermi surface is qualitatively consistent with those experimentally observed in both hole and electron-doped cuprates. On the other hand, a SC gap is almost unchanged, preserving the original simple d-wave form. Thus, it seems that the incoherent part of the singlet gap mainly influences the forms of observed gaps. |
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Keywords: | High-Tc cuprate Pseudogap Extended t– J model Variational Monte Carlo method |
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