HOLE MOTION IN AN ARBITRARY SPIN BACKGROUND - BEYOND THE MINIMAL SPIN-POLARON APPROXIMATION

The motion of a single hole in an arbitrary magnetic background is inv estigated for the two-dimensional t-J model. The wave function of the hole is described within a generalized string picture which leads to a modified concept of spin polarons. We calculate the one-hole spectral function using a large-string basis for the limits of a Neel ordered and a completely disordered background. In addition we use a simple ap proximation to interpolate between these cases. For the antiferromagne tic background we reproduce the well-known quasiparticle band. In the disordered case the shape of the spectral function is found to be stro ngly momentum dependent, the quasiparticle weight vanishes for all hol e momenta. Finally, we discuss the relevance of results for the lowest energy eigenvalue and its dispersion obtained from calculations using a polaron of minimal size as found in the literature.