2018年8月10日
(De)localization of Fermions in Correlated-Spin Background
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We study the (de)localization phenomena of one-component lattice fermions in<br />
spin backgrounds. The O(3) classical spin variables on sites fluctuate<br />
thermally through the ordinary nearest-neighbor coupling. Their complex<br />
two-component (CP$^1$-Schwinger boson) representation forms a composite U(1)<br />
gauge field on bond, which acts on fermions as a fluctuating hopping amplitude<br />
in a gauge invariant manner. For the case of antiferromagnetic (AF) spin<br />
coupling, the model has close relationship with the $t$-$J$ model of<br />
strongly-correlated electron systems. We measure the unfolded level spacing<br />
distribution of fermion energy eigenvalues and the participation ratio of<br />
energy eigenstates. The results for AF spin couplings suggest a possibility<br />
that, in two dimensions, all the energy eigenstates are localized. In three<br />
dimensions, we find that there exists a mobility edge, and estimate the<br />
critical temperature $T_{ß LD}(\delta)$ of the localization-delocalization<br />
transition at the fermion concentration $\delta$.
spin backgrounds. The O(3) classical spin variables on sites fluctuate<br />
thermally through the ordinary nearest-neighbor coupling. Their complex<br />
two-component (CP$^1$-Schwinger boson) representation forms a composite U(1)<br />
gauge field on bond, which acts on fermions as a fluctuating hopping amplitude<br />
in a gauge invariant manner. For the case of antiferromagnetic (AF) spin<br />
coupling, the model has close relationship with the $t$-$J$ model of<br />
strongly-correlated electron systems. We measure the unfolded level spacing<br />
distribution of fermion energy eigenvalues and the participation ratio of<br />
energy eigenstates. The results for AF spin couplings suggest a possibility<br />
that, in two dimensions, all the energy eigenstates are localized. In three<br />
dimensions, we find that there exists a mobility edge, and estimate the<br />
critical temperature $T_{ß LD}(\delta)$ of the localization-delocalization<br />
transition at the fermion concentration $\delta$.
- ID情報
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- arXiv ID : arXiv:1808.03419