Physical meaning and measurement of the entropic parameter q in an inhomogeneous magnetic systems

  • M. S. Reis
  • V. S. Amaral
  • R. S. Sarthour
  • I. S. Oliveira
Condensed Matter


In this paper we present a thorough analysis of two systems magnetically inhomogeneous: the manganite La0.7Sr0.3MnO3/MgO and the amorphous alloy Cu90Co10. In both cases, the non-extensive statistics yield a faithful description of the magnetic behavior of the systems. In the model proposed here, the inhomogeneous magnetic system is composed by many Maxwell-Boltzmann homogeneous bits and the entropic parameter q is related to the moments of the distribution of the inhomogeneous quantity. From the analysis of Scanning Tunnelling Spectroscopy (STS) images, the q parameter can be directly measured.


05.70.Ce Thermodynamic functions and equations of state 05.70.Fh Phase transitions: general studies 


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  1. For a complete and updated list of references, see the web site: Google Scholar
  2. C. Tsallis, Nonextensive Statistical Mechanics and Its Applications, Chap. Nonextensive Statistical Mechanics and Thermodynamics: Historical Background and Present Status, edited by S. Abe, Y. Okamoto (Springer-Verlag, Heidelberg, 2001) Google Scholar
  3. J. Lorenzana, C. Castellani, C.D. Castro, Phys. Rev. B 64, 235127 (2001) CrossRefADSGoogle Scholar
  4. J. Lorenzana, C. Castellani, C.D. Castro, Phys. Rev. B 64, 235128 (2001) CrossRefADSGoogle Scholar
  5. A. Moreo, S. Yunoki, E. Dagotto, Science 283, 2034 (1999) CrossRefGoogle Scholar
  6. E. Dagotto, T. Hotta, A. Moreo, Phys. Rep. 344, 1 (2001) CrossRefADSGoogle Scholar
  7. M. Ausloos, L. Hubert, S. Dorbolo, A. Gilabert, R. Cloots, Phys. Rev. B 66, 174436 (2002) CrossRefADSGoogle Scholar
  8. E. Dagotto, Nanoscale phase separation and colossal magnetoresistance: The physics of manganites and related compounds (Springer-Verlag, Heidelberg, 2003) Google Scholar
  9. T. Becker, C. Streng, Y. Luo, V. Moshnyaga, B. Damaschke, N. Shannon, K. Samwer, Phys. Rev. Lett. 89, 237203 (2002) CrossRefADSGoogle Scholar
  10. S. Kumar, P. Majumdar, Phys. Rev. Lett. 92, 126602 (2004) CrossRefADSGoogle Scholar
  11. K.H. Ahn, T. Lookman, A.R. Bishop, Nature 428, 401 (2004) CrossRefADSGoogle Scholar
  12. M.S. Reis, J.C.C. Freitas, M.T.D. Orlando, E.K. Lenzi, I.S. Oliveira, Europhys. Lett. 58, 42 (2002a) Google Scholar
  13. M.S. Reis, J.P. Araújo, V.S. Amaral, E.K. Lenzi, I.S. Oliveira, Phys. Rev. B 66, 134417 (2002) CrossRefADSGoogle Scholar
  14. M.S. Reis, V.S. Amaral, J.P. Araújo, I.S. Oliveira, Phys. Rev. B 68, 014404 (2003) CrossRefADSGoogle Scholar
  15. A.P. Guimarães, Magnetism and Magnetic Resonance in Solids (John Wiley, New York, 1998) Google Scholar
  16. In our previous work prb_68_2003_014404, we derived the two-branched Generalized Langevin Function. However, further calculations lead us to a more concise and general expression, valid for any real value of q and x (Eq. 3) Google Scholar
  17. C. Beck, Phys. Rev. Lett. 87, 180601 (2001) CrossRefADSMathSciNetGoogle Scholar
  18. C. Beck, E.G.D. Cohen, Physica A 322, 267 (2003) CrossRefADSMATHMathSciNetGoogle Scholar
  19. C. Renner, G. Aeppli, B. Kim, Y. Soh, S. Cheong, Nature 416, 518 (2002) CrossRefADSGoogle Scholar
  20. M. Fath, S. Freisem, A.A. Menovsky, Y. Tomioka, J. Aarts, J.A. Mydosh, Science 285, 1540 (1999) CrossRefGoogle Scholar
  21. Q. Lu, C. Chen, A. deLozanne, Science 276, 2006 (1997) CrossRefGoogle Scholar
  22. L. Zhang, C. Israel, A. Biswas, R.L. Greene, A. deLozanne, Science 298, 805 (2002) CrossRefADSGoogle Scholar
  23. E. Ferrari, F. Silva, M. Knobel, Phys. Rev. B 56, 6086 (1997) CrossRefADSGoogle Scholar
  24. N. Murillo, H. Grande, I. Etxeberria, J. DelVal, J. Gonzalez, S. Arana, F. Gracia, J. Nanoscience Nanotechnology 4, 1056 (2004) CrossRefGoogle Scholar
  25. P. Panissod, M. Malinowska, E. Jedryka, M. Wojcik, S. Nadolski, M. Knobel, J. Schmidt, Phys. Rev. B 63, 014408 (2001) CrossRefADSGoogle Scholar
  26. G. Campillo, A. Berger, J. Osorio, J. Pearson, S. Bader, E. Baca, P. Prieto, J. Magn. Magn. Mater. 237, 61 (2001) CrossRefADSGoogle Scholar
  27. T.R. McGuire, P.R. Duncombe, G.Q. Gong, A. Gupta, X.W. Li, S.J. Pickart, M.L. Crow, J. Appl. Phys. 83, 7076 (1998) CrossRefADSMathSciNetGoogle Scholar
  28. J.F. Mitchell, D.N. Argyriou, C.D. Potter, D.G. Hinks, J.D. Jorgensen, S.D. Bader, Phys. Rev. B 54, 6172 (1996) CrossRefADSGoogle Scholar
  29. P. Levy, F. Parisi, G. Polla, D. Vega, G. Leyva, H. Lanza, R.S. Freitas, L. Ghivelder, Phys. Rev. B 62, 6437 (2000) CrossRefADSGoogle Scholar
  30. A. Tkachuk, K. Rogackia, D.E. Brown, B. Dabrowski, A.J. Fedro, C.W. Kimball, B. Pyles, X. Xiong, D. Rosenmann, B.D. Dunlap, Phys. Rev. B 57, 8509 (1998) CrossRefADSGoogle Scholar
  31. H.L. Ju, Y.S. Nam, J.E. Lee, H.S. Shin, J. Magn. Magn. Mater. 219, 1 (2000) CrossRefADSGoogle Scholar
  32. K.S. Ranjan, S.S. Manoharan, Appl. Phys. Lett. 77, 2382 (2000) CrossRefGoogle Scholar

Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006

Authors and Affiliations

  • M. S. Reis
    • 1
  • V. S. Amaral
    • 1
  • R. S. Sarthour
    • 2
  • I. S. Oliveira
    • 2
  1. 1.Departamento de Física and CICECOUniversidade de AveiroAveiroPortugal
  2. 2.Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150 UrcaRio de Janeiro-RJBrasil

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