Regular Article

Enhancement of superconducting correlations by spin ordering in the spin-one-half Falicov-Kimball model with Hund and Hubbard coupling: Quantum Monte-Carlo study

Institute of Experimental Physics, Slovak Academy of Sciences Watsonova 47, 043 53 Košice, Slovakia

^a e-mail: farky@saske.sk

Received: 14 May 2020
Received in final form: 20 August 2020
Accepted: 6 October 2020
Published online: 2 December 2020

Abstract

Projector Quantum-Monte-Carlo method is used to examine effects of spin ordering on superconducting correlations in the two dimensional spin-one-half Falicov-Kimball model with Hund and Hubbard coupling. At first, the ground state spin configurations of the model are determined for a wide range of model parameters like the d-electron filling N_d, the Hund coupling J_z, the Hubbard coupling U, and then the average vertex correlation functions, as a measure of the superconducting correlations in these ground states, are calculated. It is found that the presence of the fully or partially developed antiferromagnetic spin ordering in the ground state dramatically enhances superconducting correlations in the d-wave channel, while the ferromagnetic spin substructures in the form of parallel/antiparallel domains, bands or lines superconducting correlations strongly suppress.