  We investigate the high frequency Hall effect on a two-dimensional triangular
lattice with nearest-neighbor hopping and a local Hubbard interaction. The
complete temperature and doping dependencies of the high-frequency Hall
coefficient $R_H$ are evaluated analytically and numerically for small,
intermediate, and strong interactions using various approximation schemes. We
find that $R_H$ follows the semiclassical $1/qn^*$ law near T=0, but exhibits a
striking $T$-linear behavior with an interaction- and doping-dependent slope at
high temperature. We compare our results with previous theories as well as Hall
measurements performed in the cobaltates.
