Magnetically stabilized luminescent excitations in hexagonal boron nitride

Magnetically stabilized luminescence is observed in hexagonal boron nitride . The luminescence is induced by absorption of cold neutrons and is in the visible region. In the absence of a magnetic field, the photon emission lev el is observed to decay over several hundred seconds. A fraction of this lu minescence can be suppressed if the temperature is T less than or similar t o0.6 K and the magnetic field is B less than or similar to 1.0 T. Subsequen t to irradiation and suppression, luminescence can be induced by an increas e in T or lowering of B. Possible explanations include stabilization of tri plet states or the localization and stabilization of excitons. (C) 2001 Els evier Science B,V. All rights reserved.