
Andreas Mielke
Institut for Theoretical Physics
RuprechtKarls University
Philosophenweg 19
D69120 Heidelberg
Germany
Tel.: ++49 6221 549431 (Secretary)
Fax: ++49 6221 549331
email:
mielke@tphys.uniheidelberg.de
Andreas Mielke: Stability of ferromagnetism in Hubbard models with degenerate singleparticle ground states
J. Phys. A, Math. Gen.32,
84118418
(1999)
.
AbstractA Hubbard model with a \( N_{d} \)fold degenerate singleparticle ground state has ferromagnetic ground states if the number of electrons is less or equal to \( N_{d} \). It is shown rigorously that the local stability of ferromagnetism in such a model implies global stability: The model has only ferromagnetic ground states, if there are no single spinflip ground states. If the number of electrons is equal to \( N_{d} \), it is well known that the ferromagnetic ground state is unique if and only if the singleparticle density matrix is irreducible. We present a simplified proof for this result.
BibTeXentry
@article{Mielke1999,
author="Andreas Mielke",
title="Stability of ferromagnetism in Hubbard models with degenerate singleparticle ground states",
journal="J. Phys. A, Math. Gen.",
volume="32",
pages="84118418",
year="1999"
}
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Last changes: 13.1.2018.
mielke@tphys.uniheidelberg.de
