Thermal relaxation in $a$-${\mathrm{As}}_2$${\mathrm{S}}_3$ and $a$-As

The long-time thermal relaxation has been studied in $a$ -${\mathrm{As}}_2$${\mathrm{S}}_3$ and $a$-As at temperatures below 1 K. In both materials there is a contribution to the specific heat with a logarithmic time dependence. However, the obtained density of states is not constant, as in $a$-${\mathrm{SiO}}_2$, but rather most of it indicates an $E^{-2\mathrm{}}$ dependence.