Some Properties of the Model of a~Superconductor with Pair Hopping and Magnetic Interactions at Half-Filling

• Authors: K. Kapcia
• Languages of publication: EN

Abstracts

EN

We present our preliminary studies of an effective model of a superconductor with short coherence length involving magnetic interactions. The Hamiltonian considered consists of (i) the effective on-site interaction U, (ii) the intersite magnetic exchange interactions (J^z, J^{xy}) between nearest-neighbors and (iii) the intersite charge exchange term I, determining the hopping of electron pairs between nearest-neighbor sites. In the analysis of the phase diagrams and thermodynamic properties of this model for half-filling (n=1) we have adopted the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. One finds that the system considered can exhibit very interesting multicritical behaviors (including tricritical, critical-end and bicritical points) caused by the competition between magnetism and superconductivity, even for n=1. Our investigations show that, depending on the values of interaction parameters, the system at half-filling can exhibit three homogeneous phases: superconducting (SS), (anti-)ferromagnetic (F) and nonordered (NO). The transitions between ordered phases (SS, F) and the NO phase can be first order as well as second order ones, whereas SS-F transition is first order one. Temperature dependencies of the order parameters and thermodynamic properties of the system at the sequence of transitions: SS→F→NO with increasing temperature for J/I=0.3, U/I_0 = 0.69 and n=1 are also presented.

Keywords

EN

71.10.Fd; 71.10.-w; 74.20.-z; 74.81.-g; 75.30.Fv

Discipline

• 74.81.-g: Inhomogeneous superconductors and superconducting systems, including electronic inhomogeneities
• 75.30.Fv: Spin-density waves
• 74.20.-z: Theories and models of superconducting state
• 71.10.-w: Theories and models of many-electron systems
• 71.10.Fd: Lattice fermion models (Hubbard model, etc.)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2012
• Volume: 121
• Issue: 4
• Pages: 733-737

Dates

published

2012-04

Contributors

author

K. Kapcia

• Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

References

• 1. R. Micnas, J. Ranninger, S. Robaszkiewicz, Rev. Mod. Phys. 62, 113 (1990)
• 2. D.C. Johnston, Adv. Physics 59, 803 (2010); P.M. Aswathy, J.B. Anooja, P.M. Sarun, U. Syamaprasad, Supercond. Sci. Technol. 23, 073001 (2010)
• 3. J.T. Park, D.S. Inosov, Ch. Niedermayer, G.L. Sun, D. Haug, N.B. Christensen, R. Dinnebier, A.V. Boris, A.J. Drew, L. Schulz, T. Shapoval, U. Wolff, V. Neu, X. Yang, C.T. Lin, B. Keimer, V. Hinkov, Phys. Rev. Lett. 102, 117006 (2009)
• 4. A. Ricci, N. Poccia, G. Campi, B. Joseph, G. Arrighetti, L. Barba, M. Reynolds, M. Burghammer, H. Takeya, Y. Mizuguchi, Y. Takano, M. Colapietro, N.L. Saini, A. Bianconi, Phys. Rev. B 84, 060511(R) (2011)
• 5. J. Xu, S. Tan, L. Pi, Y. Zhang, J. Appl. Phys. 104, 063914 (2008)
• 6. K. Kapcia, S. Robaszkiewicz, in preparation
• 7. R.A. Bari, Phys. Rev. B 7, 2128 (1973)
• 8. W.-C. Ho, J.H. Barry, Phys. Rev. B 16, 3172 (1977)
• 9. S. Robaszkiewicz, G. Pawłowski, Physica C 210, 61 (1993)
• 10. S. Robaszkiewicz, G. Pawłowski, Acta. Phys. Pol. A 85, 117 (1994)
• 11. K. Kapcia, S. Robaszkiewicz, R. Micnas, J. Phys., Condens. Matter 24, (2012), in press, arXiv:1203.5805
• 12. W. Kłobus, K. Kapcia, S. Robaszkiewicz, Acta. Phys. Pol. A 118, 353 (2010)
• 13. S. Murawski, K. Kapcia, G. Pawłowski, S. Robaszkiewicz, Acta. Phys. Pol. A 121, (2012), in press; arXiv:1109.2620
• 14. U. Brandt, J. Stolze, Z. Phys. B 62, 433 (1986)
• 15. K. Bernardet, G.G. Batrouni, J.-L. Meunier, G. Schmid, M. Troyer, A. Dorneich, Phys. Rev. B 65, 104519 (2002)
• 16. R. Micnas, S. Robaszkiewicz, T. Kostyrko, Phys. Rev. B 52, 6863 (1995)
• 17. J.F. Annett, B.L. Györffy, G. Litak, K.I. Wysokiński, Phys. Rev. B 78, 054511 (2008)
• 18. W.R. Czart, S. Robaszkiewicz, Acta. Phys. Pol. A 109, 577 (2006)
• 19. R. Micnas, J. Ranninger, S. Robaszkiewicz, S. Tabor, Phys. Rev. B 37, 9410 (1988); R. Micnas, J. Ranninger, S. Robaszkiewicz, Phys. Rev. B 39, 11653 (1989)

Identifiers

DOI

10.12693/APhysPolA.121.733