skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thermal expansion coefficient, scaling, and universality near the superfluid transition of /sup 4/He under pressure

Abstract

Experimental results for the isobaric-thermal-expansion coefficient ..beta../sub P/ of pressurized /sup 4/He near the superfluid transition temperature T/sub lambda/ are reported. Near T/sub lambda/, ..beta../sub P/ is an asymptotically linear function of the specific heat at constant pressure C/sub P/. Therefore these measurements yield some of the same critical-point parameters as those derivable from C/sub P/. The measurements were made with high-temperature resolution over the range 2 x 10/sup -5/ approximately-less-than vertical-bar t vertical-bar equivalent vertical-bar T/T/sub lambda/ - 1 vertical-bar < 7 x 10/sup -2/, along nine isobars. They span the pressure interval 5 approximately-less-than P approximately-less-than 30 bar. A new experimental technique was employed which yielded a temperature resolution of two parts in 10/sup 7/ and a pressure stability of 1 x 10/sup -7/ bar. The results for each isobar were fitted with the equation ..beta../sub P/ = (A/..cap alpha..) t/sup -alpha/(1 + Dt/sub x/) + B above T/sub lambda/, and with the same expression with primed coefficients below T/sub lambda/. When the amplitudes D and D' of the confluent singularity are assumed to be equal to zero (i.e., the data are fitted with a pure power law), the leading exponents are pressure dependent and vary from 0.00more » at low P to 0.06 at high P. This analysis also yields B' > B. The inequality between B and B', and the pressure dependence of ..cap alpha.. and ..cap alpha..', are contrary to the predictions of the phenomenological and renormalization-group theories of critical phenomena. When D and D' are permitted to assume nonzero values, it is statistically allowed by the data to impose the theoretically predicted relations ..cap alpha.. = ..cap alpha..', x = x', and B = B' as constraints in the analysis. With these constraints, and the value of x chosen to be equal to 0.5, we obtain pressure-independent (universal) amplitude ratios and leading exponents, as expected from theory. Their values are (AIP)« less

Authors:
; ;
Publication Date:
Research Org.:
Institut fur Festkorperforschung, Kernforschungsanlage, 517 Julich, West Germany
OSTI Identifier:
7178674
Resource Type:
Journal Article
Journal Name:
Phys. Rev., B; (United States)
Additional Journal Information:
Journal Volume: 14:5
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HELIUM 4; THERMAL EXPANSION; HELIUM II; LAMBDA POINT; MEDIUM PRESSURE; SPECIFIC HEAT; EVEN-EVEN NUCLEI; EXPANSION; HELIUM ISOTOPES; ISOTOPES; LIGHT NUCLEI; NUCLEI; PHYSICAL PROPERTIES; STABLE ISOTOPES; THERMODYNAMIC PROPERTIES; TRANSITION TEMPERATURE; 640450* - Fluid Physics- Superfluidity

Citation Formats

Mueller, K H, Ahlers, G, and Pobell, F. Thermal expansion coefficient, scaling, and universality near the superfluid transition of /sup 4/He under pressure. United States: N. p., 1976. Web. doi:10.1103/PhysRevB.14.2096.
Mueller, K H, Ahlers, G, & Pobell, F. Thermal expansion coefficient, scaling, and universality near the superfluid transition of /sup 4/He under pressure. United States. doi:10.1103/PhysRevB.14.2096.
Mueller, K H, Ahlers, G, and Pobell, F. Wed . "Thermal expansion coefficient, scaling, and universality near the superfluid transition of /sup 4/He under pressure". United States. doi:10.1103/PhysRevB.14.2096.
@article{osti_7178674,
title = {Thermal expansion coefficient, scaling, and universality near the superfluid transition of /sup 4/He under pressure},
author = {Mueller, K H and Ahlers, G and Pobell, F},
abstractNote = {Experimental results for the isobaric-thermal-expansion coefficient ..beta../sub P/ of pressurized /sup 4/He near the superfluid transition temperature T/sub lambda/ are reported. Near T/sub lambda/, ..beta../sub P/ is an asymptotically linear function of the specific heat at constant pressure C/sub P/. Therefore these measurements yield some of the same critical-point parameters as those derivable from C/sub P/. The measurements were made with high-temperature resolution over the range 2 x 10/sup -5/ approximately-less-than vertical-bar t vertical-bar equivalent vertical-bar T/T/sub lambda/ - 1 vertical-bar < 7 x 10/sup -2/, along nine isobars. They span the pressure interval 5 approximately-less-than P approximately-less-than 30 bar. A new experimental technique was employed which yielded a temperature resolution of two parts in 10/sup 7/ and a pressure stability of 1 x 10/sup -7/ bar. The results for each isobar were fitted with the equation ..beta../sub P/ = (A/..cap alpha..) t/sup -alpha/(1 + Dt/sub x/) + B above T/sub lambda/, and with the same expression with primed coefficients below T/sub lambda/. When the amplitudes D and D' of the confluent singularity are assumed to be equal to zero (i.e., the data are fitted with a pure power law), the leading exponents are pressure dependent and vary from 0.00 at low P to 0.06 at high P. This analysis also yields B' > B. The inequality between B and B', and the pressure dependence of ..cap alpha.. and ..cap alpha..', are contrary to the predictions of the phenomenological and renormalization-group theories of critical phenomena. When D and D' are permitted to assume nonzero values, it is statistically allowed by the data to impose the theoretically predicted relations ..cap alpha.. = ..cap alpha..', x = x', and B = B' as constraints in the analysis. With these constraints, and the value of x chosen to be equal to 0.5, we obtain pressure-independent (universal) amplitude ratios and leading exponents, as expected from theory. Their values are (AIP)},
doi = {10.1103/PhysRevB.14.2096},
journal = {Phys. Rev., B; (United States)},
number = ,
volume = 14:5,
place = {United States},
year = {1976},
month = {9}
}