  We studied the electronic structure of a Shastry-Sutherland lattice system,
HoB4 employing high resolution photoemission spectroscopy and ab initio band
structure calculations. The surface and bulk borons exhibit subtle differences,
and loss of boron compared to the stoichiometric bulk. However, the surface and
bulk conduction bands near Fermi level are found to be similar. Evolution of
the electronic structure with temperature is found to be similar to that
observed in a typical charge-disordered system. A sharp dip is observed at the
Fermi level in the low temperature spectra revealing signature of
antiferromagnetic gap. Asymmetric spectral weight transfer with temperature
manifests particle-hole asymmetry that may be related to the exotic properties
of these systems.
