We predict the existence of a thermal bistability in many-body systems out of
thermal equilibrium which exchange heat by thermal radiation using
insulator-metal transition (IMT) materials. We propose a writing-reading
procedure and demonstrate the possibility to exploit the thermal bistability to
make a volatile thermal memory. We show that this thermal memory can be used to
store heat and thermal information (via an encoding temperature) for arbitrary
long times. The radiative thermal bistability could find broad applications in
the domains of thermal management, information processing and energy storage