arXiv subjects

A. Penzev

Publications and source records attributed to A. Penzev.

3 recordsLinked to original sources

arXiv2009

Low frequency acoustics in solid $^4$He at low temperature

The elastic properties of hcp $^4$He samples have been investigated using low frequency (20 Hz to 20 kHz) high sensitivity sound transducers. In agreement with the findings of other workers, most samples studied grew very significantly stiffer at low temperature; Poisson's ratio $ν$ was observed to increase from 0.28 below 20 mK to $\sim 0.35$ at 0.7 K. The span of the variation of $ν$ varies from sample to sample according to their thermal and mechanical history. Crystals carefully grown at the melting curve show a different behavior, the change in $ν$ taking place at lower $T$ and being more abrupt.

cond-mat.other↗

arXiv2007

Annealing Effect for Supersolid Fraction in $^4$He

We report on experimental confirmation of the non-classical rotational inertia (NCRI) in solid helium samples originally reported by Kim and Chan. The onset of NCRI was observed at temperatures below ~400 mK. The ac velocity for initiation of the NCRI suppression is estimated to be ~10 $μ$m/sec. After an additional annealing of the sample at $T= 1.8$ K for 12 hours, ~ 10% relative increase of NCRI fraction was observed. Then after repeated annealing with the same conditions, the NCRI fraction was saturated. It differs from Reppy's observation on a low pressure solid sample.

cond-mat.other↗

arXiv1999

Threshold effect during dissolution of 3He inclusions in solid 4He

A pressure jump has been found at the onset of the dissolution of bcc inclusions in separated solid 3He-4He mixture if the crystal is overheated above a certain critical value. This effect can be explained in the framework of a multistage dissolution process model.

cond-mat.soft↗