Ultrasound velocity is one of the most sensitive probe to phase transitions. A transducer is glued on the surface of the sample to generate an acoustic pulse. When travelling through the sample the pulse energy is absorbed by degrees of freedom causing a decay of the pulse amplitude. This decay is related to the ultrasound attenuation which is measured simultaneously with sound velocity.
As an example we show results of sound velocity measurements in the cuprate high-Tc YBCO. The field dependence of the sound velocity of a longitudinal mode in YBCO with doping level p = 0.122 measured at temperatures ranging from 9.8 to 45.2 K is shown. The arrows indicate the transition towars charge order onset. Curves are shifted vertically for clarity. Click here for more details about ultrasound in YBCO.
| Pulsed field | Static field | |
|---|---|---|
| Bmax | 90 T | 36 T |
| Temperature range | 0.5 K - 300 K | 0.05 K - 300 K |