  We investigate the insulating phase that forms in a titanium nitride film in
a close vicinity of the disorder-driven superconductor-insulator transition. In
zero magnetic field the temperature dependence of the resistance reveals a
sequence of distinct regimes upon decreasing temperature crossing over from
logarithmic to activated behavior with the variable-range hopping squeezing in
between. In perpendicular magnetic fields below 2 T, the thermally activated
regime retains at intermediate temperatures, whereas at ultralow temperatures,
the resistance increases faster than that of the thermally activated type. This
indicates a change of the mechanism of the conductivity. We find that at higher
magnetic fields the thermally activated behavior disappears and the
magnetoresistive isotherms saturate towards the value close to quantum
resistance h/e^2.
