Time-resolved measurements of photoinduced change in electrical conductivity of the molecular conductor lambda-(BETS)(2)FeCl4

Abstract

Photoinduced change in electrical conductivity of the magnetic molecular conductor lambda-(BETS)(2)FeCl4, where BETS represents bis(ethylenedithio)tetraselenafulvalene, has been examined with nanosecond laser pulse excitation. Time-resolved measurements of the photocurrent have been carried out at low temperatures across the T-MI at which phase transition occurs between the metallic phase and the antiferromagnetic insulating phase. Transient increase of the electrical conductivity is induced by photoexcitation at any temperatures across the T-MI. Time profile of the transient photoresponse shows a maximum of the peak amplitude near the T-MI. The decay lifetime of the photoresponse divergently increases at temperatures lower than the T-MI, as the temperature approaches the T-MI. This result is ascribed to the critical slowing down in antiferromagnets. The dimensionality of the magnetic coupling is discussed on the basis of the critical exponent of the observed divergence. (C) 2015 Elsevier Ltd. All rights reserved.