Aug 17, 1999
Magnetization Plateaux in Quasi-One-Dimensional Strongly Correlated Electron Systems
Daniel Cabra, (Univ Nac'l de la Plata)
We summarize our results in the study of magnetization plateaux
in different quasi-one-dimensional strongly correlated electron systems,
such as N-leg Heisenberg antiferromagnetic ladders, p-merized Heisenberg
chains (chains with a periodically modulated exchange).
In all cases, the quantization condition for the magnetization M at a
plateaux is given by:
pSN(1-M) = integer
where S is the spin at a site (see also work by M. Oshikawa, M. Yamanaka and
I. Affleck; Phys. Rev. Lett. 78, 1984 (1997) and cond-mat/9701141, and by K.
Totsuka, Phys. Rev. B57 (1998) 3454).
We also present new results in the study of charged systems, such as
the p-merized one-dimensional Hubbard model (here the hopping exchange
is periodically modulated). In this case we found two different
situations, for a given magnetization M and filling n:
* If both conditions p/2(n + M) and p/2(n-M) are satisfied, a plateaux
appears in the magnetization curve and there is a charge gap.
* If only one of these conditions is satisfied and in addition
n is kept fixed, then a magnetization plateau opens, but one mode
remains gapless.
cond-mat/9908398, cond-mat/9810263, cond-mat/9802035
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