Formation and local symmetry of the Holstein polaron in the t–J model

The formation and local symmetry of a spin–lattice polaron has been investigated semiclassically in planar Holstein t–J-like models within the exact diagonalization method. Due to the interplay of strong correlations and electron–lattice interaction, the doped hole may either move freely or lead to the localized spin–lattice distortion and form a Holstein polaron. The formation of a polaron breaks the translational symmetry by suppression of antiferromagnetic correlations and inducement of ferromagnetic correlations locally. Moreover, the breaking of local rotational symmetry around the polaron has been shown. The ground state is generically a parity singlet and the first excited state may be a parity doublet. Further consequences of the density of states spectra for comparison with scanning tunneling microscopy experiments are discussed. (paper)