Bose-Einstein condensation in liquid He-4 near the liquid-solid transition line

Article

关键词: INELASTIC NEUTRON-SCATTERING;    SUPERFLUID TRANSITION;    MOMENTUM DISTRIBUTION;    KINETIC-ENERGY;    HELIUM;    HE-4;    SUPERSOLIDITY;    GASES;   

DOI  :  10.1103/PhysRevB.85.140505

来源: SCIE

【 摘 要 】

We present precision neutron scattering measurements of the Bose-Einstein condensate (BEC) fraction n(0)(T) and the atomic momentum distribution n(star)(k) of liquid He-4 as a function of temperature at pressure p = 24 bars. Both the temperature dependence of n(0)(T) and of the width of n(star)(k) are determined. The n(0)(T) can be represented by n(0)(T) = n(0)(0)[1 -(T/T-lambda)(gamma)] with a small n(0)(0) = 2.80 +/- 0.20% and large gamma = 13 +/- 2 for T < T-lambda, indicating a strong interaction. The onset of BEC is accompanied by a significant narrowing of the n(star)(k). The narrowing accounts for 65% of the drop in kinetic energy below T-lambda and reveals an important coupling between BEC and k > 0 states. The experimental results are well reproduced by path integral Monte Carlo calculations.

【 授权许可】

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