Evaluation of specific heat for superfluid helium between 0 - 2.1 K based on nonlinear theory

TL;DR

This paper presents a nonlinear theoretical approach to calculate the specific heat of superfluid helium between 0 and 2.1 K, achieving improved agreement with experimental data by incorporating temperature-dependent excitation energy.

Contribution

It introduces a nonlinear formulation of the total energy based on excitation energy and latent heat, enhancing the accuracy of specific heat predictions for superfluid helium.

Findings

Second iteration results align well with experimental data

Nonlinear energy form improves temperature dependence modeling

Method uses elementary excitation energy at 1.1 K for calculations

Abstract

The specific heat of liquid helium was calculated theoretically in the Landau theory. The results deviate from experimental data in the temperature region of 1.3 - 2.1 K. Many theorists subsequently improved the results of the Landau theory by applying temperature dependence of the elementary excitation energy. As well known, many-body system has a total energy of Galilean covariant form. Therefore, the total energy of liquid helium has a nonlinear form for the number distribution function. The function form can be determined using the excitation energy at zero temperature and the latent heat per helium atom at zero temperature. The nonlinear form produces new temperature dependence for the excitation energy from Bose condensate. We evaluate the specific heat using iteration method. The calculation results of the second iteration show good agreement with the experimental data in the temperature region of 0 - 2.1 K, where we have only used the elementary excitation energy at 1.1 K.