Optimal doping for d-wave superconducting ground states within the generalized Hubbard model

Benjamin Millan, Luis Antonio Perez, Jose Samuel Millan


A single-band generalized Hubbard model that describes two-dimensional superconductivity with d-wave symmetry on a square lattice within the BCS formalism is considered. For a set of Hamiltonian parameters and varying the ratio between nearest-neighbor and next-nearest neighbor hoppings (t'/t), an optimal doping (nop) can be found for each t'/t value, where the critical temperature is maximum (Tc-max). After calculating the superconducting gap at T=0K and the corresponding ground state (Eg ) for all the carrier concentrations, a ground state energy minimum (Eg-min) is found close to half filling. Since Tc-max is the highest critical temperature for a given ratio t'/t, the minimum of all the Tc-max values defines a supreme of this set of temperatures, named as Tc-max-sup. The corresponding optimal doping for Tc-max-sup will be called nop-sup, and the the results show that  Eg-min is located at nop-sup. The Fermi surface (FS) is analyzed for carrier concentrations close to nop-sup and it is suggested that the location for over (OD) and under (UD) doping regimes (nOD>nop-sup>nUD) could define a pseudogap zone for high critical temperature superconductors.


Theories and models of superconducting state; Pairing symmetries (other than s-wave); Pseudogap regime

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DOI: https://doi.org/10.31349/RevMexFis.64.233


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REVISTA MEXICANA DE FÍSICA, year 67, issue 2, March-April 2021. Bimonthly Journal published by Sociedad Mexicana de Física, A. C. Departamento de Física, 2º Piso, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Alcaldía Coyacán, C.P. 04510 , Ciudad de México. Apartado Postal 70-348. Tel. (+52)55-5622-4946, https://rmf.smf.mx/ojs/rmf, e-mail: rmf@ciencias.unam.mx. Chief Editor: José Alejandro Ayala Mercado. INDAUTOR Certificate of Reserve: 04-2019-080216404400-203, ISSN: 2683-2224 (on line), 0035-001X (print), both granted by Instituto Nacional del Derecho de Autor. Responsible for the last update of this issue, Technical Staff of Sociedad Mexicana de Física, A. C., Fís. Efraín Garrido Román, 2º. Piso, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Alcaldía Coyacán, C.P. 04510 , Ciudad de México. Date of last modification, March 1st., 2021.

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