Ruprecht-Karls-Universität Heidelberg
University of HeidelbergFaculty of Physics and AstronomyInstitut of Theoretical PhysicsAndreas MielkeAndreas Mielkeemail

Andreas Mielke
Institut for Theoretical Physics
Ruprecht-Karls University
Philosophenweg 19
D-69120 Heidelberg
Germany
Tel.: ++49 6221 549431 (Secretary)
Fax: ++49 6221 549331
e-mail: mielke@tphys.uni-heidelberg.de


Andreas Mielke: Stability of ferromagnetism in Hubbard models with degenerate single-particle ground states
J. Phys. A, Math. Gen.32, 8411-8418 (1999) .

Archiv: cond-mat/9910385

Abstract

A Hubbard model with a \( N_{d} \)-fold degenerate single-particle 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 spin-flip 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 single-particle density matrix is irreducible. We present a simplified proof for this result.

BibTeX-entry

@article{Mielke1999,
author="Andreas Mielke",
title="Stability of ferromagnetism in Hubbard models with degenerate single-particle ground states",
journal="J. Phys. A, Math. Gen.",
volume="32",
pages="8411-8418",
year="1999"
}

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Last changes: 15.11.2017. mielke@tphys.uni-heidelberg.de