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The influence of long-range hopping on ferromagnetism in the Hubbard model

P. Farkasovsky
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Abstract

The phase diagram of the Hubbard model in an external magnetic field is examined by extrapolation of small-cluster exact-diagonalization calculations. Using a general expression for the hopping matrix elements ($t_{ij}\sim q^{|i-j|}$) the influence of long-range hopping (band asymmetry) on ferromagnetism in this model is studied. It is found that the long-range hopping (nonzero $q$) stabilizes ferromagnetism in an external magnetic field for $n > 1$. In the opposite limit $n \leq 1$ the fully polarized ferromagnetic state is generally suppressed with increasing $q$. The critical value of magnetic field $h$ below which the ferromagnetic state becomes unstable is calculated numerically.

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P. Farkasovsky. 1997-12-31. The influence of long-range hopping on ferromagnetism in the Hubbard model. https://doi.org/10.1142/s0217979298000466

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