Abstract

The experimentally observed low temperature magnetic behaviour of mixed valent Tm ions has till now not been demonstrated by theories1,2 It is shown here that if the diagramatic perturbation theory of Read etal. is extended to include the f0 level, magnetic ground state becomes possible for proper choice of parameters. The Hamiltonian for an f0-f1-f2 system is written, with usual notations, as
$$H = {E_0}|0{\rm{ > < }}0| + {E_1}\sum\limits_m | 1m{\rm{ > < }}1m| + {E_2}\sum\limits_{mmr} | 2mm{\rm{ > < }}2mm'| + \sum\limits_{k,m} {c_{km}^ + } {c_{km}} + \sum {(u|} 0{\rm{ > < }}1m|c_{km}^ + + {\rm{h}}{\rm{.c}}{\rm{.}}) + \sum\limits_{kmm'} {(v|} 1m{\rm{ > < }}2mm'|c_{km'}^ + + {\rm{h}}{\rm{.c}}{\rm{.}})$$
(1)
where Ei(i=0, 1, 2) is the energy of the state fi

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References

  1. 1.
    Yafet, Y. and Varma, C.M. Phys. Rev. B 32 (1985) 360.CrossRefGoogle Scholar
  2. 2.
    Read, N., Dharamvir, K., Rasul, J.W. and Newns, D.M., J. Phys. C. 19(1986) 1597.CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • K. Dharamvir
    • 1
  1. 1.Physics DepartmentPanjab UniversityChandigarhIndia

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