Heat capacity of solid He 4 and He 3 - He 4 mixture grown in aerogel

Zhi Gang Cheng, Norbert Mulders, Moses Hung-Wai Chan

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We report heat capacity measurements of solid He4 and He3-He4 solid mixture samples grown in silica aerogel. In addition to the Debye T3 term, the heat capacity of solid He4 samples includes T linear and T2 terms which are attributed to the amorphous and two-dimensional helium layers confined near the silica strands of aerogel. Beside these regular polynomial terms, a broad heat capacity peak is found between 0.1 and 0.35 K. The peak probably has its origin in the vibration of the dislocation lines pinned by the silica strands. Compared to He4 samples, the heat capacity of solid He3-He4 mixture samples shows evidence of phase separation below a characteristic temperature Tc that increases with He3 concentration (X3). Below this temperature the heat capacity shows X31/2 dependence suggesting that the He3 atoms are phase separated from being uniformly distributed in the pore space into two-dimensional patches enfolding the silica strands that are themselves coated with a strongly bound amorphous He4 layer.

Original languageEnglish (US)
Article number224101
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number22
DOIs
StatePublished - Dec 1 2014

Fingerprint

Aerogels
aerogels
Specific heat
Silicon Dioxide
specific heat
Silica
strands
silicon dioxide
Helium
Phase separation
polynomials
helium
Polynomials
porosity
Atoms
vibration
Temperature
temperature
atoms

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Cheng, Zhi Gang ; Mulders, Norbert ; Chan, Moses Hung-Wai. / Heat capacity of solid He 4 and He 3 - He 4 mixture grown in aerogel. In: Physical Review B - Condensed Matter and Materials Physics. 2014 ; Vol. 90, No. 22.
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Heat capacity of solid He 4 and He 3 - He 4 mixture grown in aerogel. / Cheng, Zhi Gang; Mulders, Norbert; Chan, Moses Hung-Wai.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 90, No. 22, 224101, 01.12.2014.

Research output: Contribution to journalArticle

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AB - We report heat capacity measurements of solid He4 and He3-He4 solid mixture samples grown in silica aerogel. In addition to the Debye T3 term, the heat capacity of solid He4 samples includes T linear and T2 terms which are attributed to the amorphous and two-dimensional helium layers confined near the silica strands of aerogel. Beside these regular polynomial terms, a broad heat capacity peak is found between 0.1 and 0.35 K. The peak probably has its origin in the vibration of the dislocation lines pinned by the silica strands. Compared to He4 samples, the heat capacity of solid He3-He4 mixture samples shows evidence of phase separation below a characteristic temperature Tc that increases with He3 concentration (X3). Below this temperature the heat capacity shows X31/2 dependence suggesting that the He3 atoms are phase separated from being uniformly distributed in the pore space into two-dimensional patches enfolding the silica strands that are themselves coated with a strongly bound amorphous He4 layer.

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