LASER-INDUCED THERMOMAGNETIC DETECTION OF A METASTABLE BAND IN BISMUTH

Thermal gradients were induced in bismuth films (5.5 m thick) by 5-nsec laser pulses of moderate intensity (3×109 W/m2) under an applied magnetic field. The temporal evolution of the thermal gradient, when predicted by the heat-diffusion equation, does not correlate with the observed temporal evolution of the laser-induced thermomagnetic potential in the films. A new source term is introduced into the equation given by the electrons optically pumped to a metastable band. Agreement between experimental results and theoretical prediction is obtained. Estimations of the lifetime and the energy of the metastable band are given as well. © 1990 The American Physical Society.