Variable-temperature photoacoustic effect: Application to phase transition

Abstract

A low-temperature-adapted photoacoustic cell using an electret microphone and a MOSFET preamplifier is described. This cell can operate between 5 and 300 K in a gas-flow cryostat. By way of illustration, it is used here to perform a new kind of photoacoustic measurement, i.e., to study the specific-heat anomaly of various insulators in the neighborhood of magnetic phase transitions.