Eur. Phys. J. B 21, 527-533 (2001)
https://doi.org/10.1007/s100510170163

Antiferromagnetism and superconductivity in a model with extended pairing interactions

¹ Department of Physics & Meteorology, Indian Institute of Technology, Kharagpur 721302, India
² University of Neuchâtel, rue de Breguet 1, 2000 Neuchâtel, Switzerland
³ Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India

Corresponding authors: ^a tulika@phy.iitkgp.ernet.in - ^b Hans.Beck@unine.ch - ^c arghya@phy.iitkgp.ernet.in

Received: 30 November 2000
Revised: 27 March 2001
Published online: 15 June 2001

Abstract

The competition between antiferromagnetism and the superconducting state is studied in a model with near and next near neighbour interactions in the absence of any on-site repulsion. A mean field study shows that it is possible to have simultaneous occurrence of an antiferromagnetic and a singlet superconducting state in this model. In addition, such a coexistence generates a triplet superconducting order parameter with centre of mass momentum dynamically having the same orbital symmetry as the singlet superconductor. Inclusion of next nearest neighbour hopping in the band stabilises the d_xy superconducting state away from half filling, the topology of the phase diagram, though, remains similar to the near neighbour model. In view of the very recent observation of a broad region of coexistence of antiferromagnetic and unconventional superconducting states in organic superconductors, the possibility of observation of the triplet state has been outlined.