Electronic, Magnetic and Structural Properties of the RFeO3 Antiferromagnetic-Perovskites at Very High Pressures


At ambient pressure the orthorhombic perovskites R-orthoferrites (R ≡ Lu, Eu, Y, Pr, and La) exhibit very large optical gaps. These large- gap Mott insulators in which the 3d5 high-spin ferric ions carry large local moments and magnetically order at TN > 600 K, undergo a sluggish structural first-order phase transition in the 30-50 GPa range, with the exception of the LuFeO3 which undergoes an isostructural volume reduction resulting from a high to low-spin crossover. High-pressure methods to 170 GPa using Mossbauer spectroscopy, resistance, and synchrotronbased XRD in diamond anvil cells were applied. Following the quasi-isostructural volume reduction (3-5%) the new phase the magnetic-ordering temperature is drastically reduced, to ~ 100 K, the direct and super-exchange interactions are drastically weakened, and the charge-transfer gap is substantially reduced. The high-pressure (HP) phases of the La and Pr oxides, at their inception, are composed of high- and low-spin Fe3+ magnetic sublattices, the abundance of the latter increasing with pressure but HP phases of the Eu, Y, and Lu oxides consist solely of low-spin Fe3+. Resistance and Mössbauer studies in La and Pr orthoferrites reveal the onset of a metallic state with moments starting at P > 120 GPa. Based on the magnetic and electrical data of the latter species, a Mott phase diagram was established.

This is a preview of subscription content, access via your institution.


  1. 1

    M. Eibschutz, S. Strikman, and D. Treves, Phys. Rev. 158, 562 (1967).

    Article  Google Scholar 

  2. 2

    W.M. Xu, O. Naaman, G.Kh. Rozenberg, M.P. Pasternak, and R.D. Taylor, Phys. Rev B 64, 094411 (2001).

    Article  Google Scholar 

  3. 3

    M. P. Pasternak, G.Kh. Rozenberg, G. Yu. Machavariani, O. Naaman, R. D. Taylor, and R. Jeanloz, Phys. Rev. Letters. 82, 4663 (1999).

    CAS  Article  Google Scholar 

  4. 4

    An exceptional case of a temperature-dependent Mott transition has been observed in RNiO3 (see J. B. Torrance et al., Phys. Rev. B 45, 8209 (1992)).

  5. 5

    The Hubbard Hamiltonian, \(H = \sum {{t_{ij}}a_{i\sigma } + {a_{j\sigma }} + } U\sum {n_i \uparrow n_i \downarrow }\) is the simplest description of a Mottinsulator (J. Hubbard, Proc. Royal. Soc. A 277, 237 (1964). It is characterized by a kinetic energy term tij denoting the hopping of an electron from site i to its nearest neighbor site j and by the extra energy cost U of putting two electrons (nini) on the same site. The bandwidth W is proportional to t. In the case of charge transfer insulator, U, the energy gap separating the empty and filled d-bands Δ, is replaced by, a gap between the empty d-band and filled-ligand bands (J. G. Zaanen, G. A. Sawatzky, and J. W. Allen, Phys. Rev. Letters 55, 418 (1985)). With pressure increase the bandwidth increases allowing the use of P as a measure of t/U.

  6. 6

    S. A. Carter, T. F. Rosenbaum, M. Lu, and H. M. Jaeger, P. Metcalf, J. M. Honig, and J. Spalek, Phys. Rev. B 49, 7898 (1994).

    CAS  Article  Google Scholar 

  7. 7

    G.Yu. Machavariani, M P. Pasternak, G.R. Hearne, and G.Kh. Rozenberg, Rev. Sci. Instr. 69, 1423 (1998).

    CAS  Article  Google Scholar 

  8. 8

    Due to the proximity of electrodes (~ 10 µm), there was no need for a pressure medium.

  9. 9

    A.P. Hammersley, S.O. Svensson, M. Hanfland, A.N. Fitch, and D. Hausermann, High Pressure Res. 14, 235 (1996).

    Article  Google Scholar 

  10. 10

    G.R. Hearne, M. P. Pasternak, and R. D. Taylor, Rev. Sci. Inst. 65, 3787 (1994).

    CAS  Article  Google Scholar 

  11. 11

    The IS in 57Fe is proportional to the negative value of the s-electron density at the nucleus ρs(0). Decrease in IS is concomitant to the increase in ρs(0), e.g., in the density at and around the Fe ion.

  12. 12

    D.M. Sherman in Advances in Physical Geochemistry, edited by S. K. Saxena, (Springer-Verlag, 1988) V. 7, p. 113.

    Article  Google Scholar 

  13. 13

    I. Nowik and H. H. Wickman, Phys. Rev. Lett. 17, 949 (1966).

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Moshe P. Pasternak.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Pasternak, M.P., Xu, W.M., Rozenberg, G.K. et al. Electronic, Magnetic and Structural Properties of the RFeO3 Antiferromagnetic-Perovskites at Very High Pressures. MRS Online Proceedings Library 718, 27 (2002). https://doi.org/10.1557/PROC-718-D2.7

Download citation