Structural, electronic and magnetic properties of KMF₃(M=Mn, Fe, Co, Ni)

Abstract

The structural, electronic and magnetic properties of the perovskite systems KMF₃ (M=Mn, Fe, Co, Ni) have been investigated with CRYSTAL95, a periodic abinitio Hartree–Fock program. An all-electron Gaussian basis set has been used. The equation of state has been determined first for the cubic structure; then deviations from cubic symmetry have been explored, with the result that the Mn, Fe and Co systems are found to be slightly more stable in a tetragonal geometry. The systems are almost fully ionic, with net charges for K and M of +1, ca. -0.9 and ca. +1.8 ∣e∣, respectively. The antiferromagnetic (AFM) is always more stable than the ferromagnetic (FM) phase; the energy difference ΔE=E(FM)-E(AFM) is shown: (a) to be additive with respect to the number of M–M first neighbours; (b) to increase with decreasing lattice parameter according to an inverse power law; and (c) to become zero when the M–F^{–M angle approaches 90°. The super-exchange coupling constants, evaluated from ΔE by using an Ising model hamiltonian, are in qualitative agreement with the experimental data (from 30% to 45% of the latter). Mulliken population data, charge and spin density maps and density of states are used to illustrate the electronic structure.}

References

1. J. G. Bednorz and K. A. Múller, in Earlier and Recent Aspects of Superconductivity, Springer, New York, 1990.
2. L. J. de Jongh and R. Block, Physica B, 1975, 79, 568.
3. L. J. de Jongh and R. A. Miedema, Adv. Phys., 1974, 23, 1.
4. J. A. Mejías and J. Fernández Sanz, J. Chem. Phys., 1995, 102, 2.
5. F. Illas, J. Casanovas, M. A. Garcia-Bach, R. Caballol and O. Castell, Phys. Rev. Lett., 1993, 71, 549.
6. J. Casanovas and F. Illas, J. Chem. Phys., 1994, 100, 8257.
7. J. Casanovas, J. Rubio and F. Illas, in New Challenges in Computational Quantum Chemistry, ed. R. Broer, P. J. C. Aerts and P. S. Bagus, University of Groningen, Groningen, 1994, pp. 214–226.
8. J. Casanovas and F. Illas, Phys. Rev. B, 1994, 50, 3798.
9. J. Casanovas, J. Rubio and F. Illas, Phys. Rev. B, 1996, 53, 945.
10. I. de P. R. Moreira and F. Illas, Phys. Rev. B, 1997, 55, 1.
11. G. Pari, S. Mathi Jaya and R. Asokamani, Phys. Rev. B, 1994, 50, 8166.
12. W. E. Pickett, Rev. Mod. Phys., 1989, 61, 433.
13. A. Svane, Phys. Rev. Lett., 1992, 68, 1900.
14. A. Svane and O. Gunnarsson, Phys. Rev. Lett., 1990, 65, 1148.
15. M. T. Czyzyk and G. A. Sawatzky, Phys. Rev. B, 1994, 49, 14211.
16. V. I. Anisimov, M. A. Korotin, J. A. Zaanen and O. K. Andersen, Phys. Rev. Lett., 1992, 68, 345.
17. P. Wei and Z. Q. Qi, Phys. Rev. B, 1994, 49, 12519.
18. R. Dovesi, V. R. Saunders, C. Roetti, M. Causà, N. M. Harrison, R. Orlando and E. Aprà, CRYSTAL95 user documentation, Università di Torino, Torino, 1995.
19. W. C. Mackrodt, N. M. Harrison, V. R. Saunders, N. L. Allan, M. D. Towler, E. Aprà and R. Dovesi, Phil. Magaz., 1993, 68, 653.
20. M. Catti, G. Valerio and R. Dovesi, Phys. Rev. B, 1995, 51, 7441.
21. M. Catti, G. Sandrone, G. Valerio and R. Dovesi, J. Phys. Chem. Solids, 1996, 57, 1735.
22. G. Valerio, M. Catti, R. Dovesi and R. Orlando, Phys. Rev. B, 1995, 54, 2422.
23. F. Freyria Fava, Thesis, Torino University, Torino, 1995.
24. J. M. Ricart, R. Dovesi, C. Roetti and V. R. Saunders, Phys. Rev. B, 1995, 52, 2381; erratum: Phys. Rev. B, 1997, 55, 15942.
25. M. D. Towler, R. Dovesi and V. R. Saunders, Phys. Rev. B, 1995, 52, 10150.
26. C. Pisani, R. Dovesi and C. Roetti, in Lecture Notes in Chemistry, Springer, Heidelberg, vol. 48, 1988.
27. V. R. Saunders, C. Freyria Fava, R. Dovesi, L. Salasco and C. Roetti, Mol. Phys., 1992, 77, 629.
28. A. Okazaki and Y. Suemune, J. Phys. Soc. Jpn., 1975, 16, 671.
29. B. Okai and J. Yoshimoto, J. Phys. Soc. Jpn., 1975, 39, 162.
30. V. J. Minkiewicz, Y. Fujii and Y. Yamada, J. Phys. Soc. Jpn., 1970, 28, 443.
31. J. P. Perdew, in Electronic Structure of Solids '91, ed. P. Ziesche and H. Eschrig, Akademie Verlag, Berlin, 1991.
32. J. S. Smart, Phys. Chem. Solids, 1959, 11, 97.
33. D. J. Breed, K. Gilijamse and A. R. Miedema, Physica, 1969, 45, 205.
34. P. A. Cox, in Transition Metal Oxides, Oxford Science Publications, Clarendon Press, Oxford, 1992, p. 151.
35. Landolt-Börnstein New Series, ed. Madelung, Springer, Berlin, 1982.
36. M. Hidaka, J. Phys. Soc. Jpn., 1975, 39, 180.
37. N. Miyata, K. Tanaka and F. Marumo, Acta Crystallogr. Sect. B, 1983, 39, 561.
38. M. Rousseau, J. Nouet and A. Zarembovitch, J. Phys. Chem. Solids, 1974, 35, 921.
39. C. G. Windsor and R. W. H. Stevenson, Proc. Phys. Soc., 1966, 87, 501.
40. S. J. Pickart, M. F. Collins and C. G. Windsor, J. Appl. Phys., 1966, 37, 1054.
41. Y. Yamaguchi and N. Sakamoto, J. Phys. Soc. Jpn., 1969, 27, 1444.
42. S. R. Chinn, H. J. Zeiger and R. J. O'Connor, Phys. Rev. B, 1971, 3, 1709.
43. J. P. Perdew, Phys. Rev. B, 1986, 33, 8822; 1986, 34, 7406(E); J. P. Perdew, J. A. Chevary, S. H. Vosko, K. A. Jacson, M. R. Pederson, D. J. Singh and C. Fiolhais, Phys. Rev. B, 1992, 46, 6671.