Dimensionality Dependence in Self-Trapping of Excitons

概要

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Self-trapping (ST) of excitons (or electrons) interacting with phonons via short-range potentials depends strongly on the degree of freedom of their motion on the lattice. When excitons can move three-dimensionally, the self-trapped (S) state appears suddenly as a strongly-localized one when the coupling constant (g) exceeds a certain critical value. Free (F) states do not become unstable however large g is. When exciton motion is limited only in one dimension, excitons are always self-trapped and F states are unstable irrespective of the magnitude of g (≠0). The S state appears as a strongly-extended one in the limit of g→0, and its spatial extension decreases as g increases . For excitons mobile in two dimensions, there exist two critical values g_<cl> and g_<C2> (>g_<c1>) of g : The S state appears suddenly as a strongly-localized one when g exceeds g_<c1>, but F states become unstable when g exceeds g_<c2> although they are metastable for g_<c1><g<g_<c2>.
社団法人日本物理学会の論文
1994-02-15