CONDENSED MATTER PHYSICS:
Hot Electrons in Magnetic Oxides
B. Keimer
If electrons in a material are given energy by an applied electric field, they can ionize the atoms of the material to yield more electrons. This process can continue toward an electron "avalanche" and is the basis for a variety of electronic devices such as photodetectors and semiconductor switches. In his Research Commentary, Keimer discusses results reported by Fiebig et al. in which an unusual kind of avalanche instability has been observed in a manganese oxide material. This type of material is of interest for its colossal magnetoresistance--a phenomenon in which the substance becomes highly sensitive to magnetic fields. The authors are able to use optical imaging to detect the reflectivity changes that occur when laser pulses are used to induce a transition from an insulating phase to a conducting phase; the current that flows through the conducting material in turn maintains the phase transition after the laser pulse is off. The findings reveal new physics and the potential for new device applications.
The author is in the Department of Physics, Princeton University, Princeton, NJ 08544, USA. E-mail: keimer{at}pupgg.princeton.edu
