Phonon-roton model for compressed He II

✍ Scribed by R.L Mills

• Publisher: Elsevier Science
• Year: 1965
• Tongue: English
• Weight: 781 KB
• Volume: 35
• Category: Article
• ISSN: 0003-4916
• DOI: 10.1016/0003-4916(65)90247-2

✦ Synopsis

The separate phonon and roton entropies are s _ 2r2k4T3

ph--, 45fl3q3p and

(3)

where Ic, fi, p, and T have their usual meanings, cl is the velocity of first sound at absolute zero, and A, po , and P are parameters of energy, momentum, and effective mass, respectively, which charact.erize the roton. Since the phonon ent,ropy is easily calculable from existing density and sound velocity data (e-8)) one may by subtraction from the total entropy compute the roton entropy and gain some insight concerning the parameters A, po , and p.

The Landau model has been found to be consistent with thermal expansion data on the vapor curve from about 0.85 t'o 2°K (9, 10). It is the purpose of the present paper to analyze the 0~~ data on compressed He II (1) in terms of the Landau model.