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High Pressure Research
An International Journal
Volume 24, 2004 - Issue 1
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Original Articles

Effect of very high pressure on the magnetic state of transition metal compounds

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Pages 33-43 | Received 16 May 2003, Accepted 25 Aug 2003, Published online: 08 Jun 2010

References

  • Mott N. F. Metal–Insulator Transitions Taylor & Francis London/Philadelphia (1990) and references therein
  • An exceptional case of a temperature-dependent Mott transition has been observed in RNiO3 (see Torrance J. B. et al. Phys. Rev. B45 8209 (1992)
  • The Hubbard Hamiltonian H = ∑ t ij a iσ + a jσ + U∑ n i ↑ n i ↓, is the simplest description of a Mott-insulator ( Hubbard J. Proc. Royal Soc. A277 237 (1964) ). It is characterized by a kinetic energy term t ij 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 (n i ↑ n i ↓) 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, is replaced by Δ, a gap between the empty d-band and filled-ligand bands ( Zaanen J. G. Sawatzky G. A. Allen J. W. Phys. Rev. Lett. 55 418 (1985)
  • It is of note that the CF splitting increases proportional to the inverse of the fifth power of the TM-ligand-bond length ( Sherman D. M. In: S. K. Saxena, (Ed.) Advances in Physical Geochemistry 7 Springer-Verlag Berlin (1988) p. 113
  • Sterer , E. , Pasternak , M. P. and Taylor , R. D. (1990) . Rev. Sci. Instrum. , 61 : 1117
  • Purchased from D'Anvils Ltd.http://www.danvils.com
  • Pure elemental I2 was prepared by thermal dissociation at 300 °C of spectroscopical pure PdI2 and condensation of I2 vapor in the same evacuated tube
  • Due to the proximity of electrodes (∼10 µm), there was no need for a pressure medium
  • Hammersley , A. P. , Svensson , S. O. , Hanfland , M. , Fitch , A. N. and Hausermann , D. (1996) . High Pressure Res. , 14 : 235
  • Hearne , G. R. , Pasternak , M. P. and Taylor , R. D. (1994) . Rev. Sci. Inst. , 65 : 3787
  • The ground state 2 T 2g of the low-spin 5d-electrons configuration in Fe3+ is (t 2g * ↑) 3 (t 2g *↓)2 with a magnetic moment approximately 1/5 of that of the high-spin 6 A 1g ground state
  • Note that following the first compression cycle (filled circle curve), R(P) upon decompression reaches a value that is lower at∼5 GPa. Successive compression and decompression cycles are reproducible. This phenomenon can be explained as due to compacting of the sample during the first compression cycle
  • The TN for each pressure was deduced from H hf(T, P) measurements and extrapolation to H hf = 0
  • The quadrupole splitting QS is half the value of the quadrupole coupling e 2 q zz Q
  • Pasternak , M. P. (1999) . Phys. Rev. Lett. , 82 : 4663
  • Rozenberg G. Kh. Pasternak M. P. Taylor R. D. (to be published)
  • Xu , W. M. , Naaman , O. , Rozenberg , G. Kh. , Pasternak , M. P. and Taylor , R. D. (2001) . Phys. Rev. B , 64 : 094411
  • Pasternak , M. P. , Xu , W. M. , Rozenberg , G. Kh. , Taylor , R. D. , Hearne , G. R. and Sterer , E. (2001) . Phys. Rev. B , 65 : 035106

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