Thermodynamic, Elastic, and Magnetic Properties of Solid Helium

Anisotropy of the nuclear magnetic relaxation times induced in solid 3He by modulation of the dipolar interactions

“…However, the K2 value just as the T2 dependence on the magnetic field orientation were consistent with the expected anisotropic relaxation times [9] for a single crystal deduced from the anisotropy of the second moment of the resonance line [10]. The properties of solid helium have been extensively studied in other fields : measurements of the thermal conductivity [11], sound propagation [12,13,14] and ionic mobilities [15], which require high quality monocrystalline samples. New constant pressure growing techniques have been used in which the temperature of the filling capillary is maintained slightly above the melting temperature of the solid [11] in order to avoid the blocking of the capillary.…”

Dynamic diffuse scattering of X‐rays in fcc 4He

“…Furthermore, measured hu Q 2 i values agree with the PIMC computations within about one percent. Besides traditional experimental approaches [5,6], different techniques are being employed to explore further the properties of solid helium. These include extremely high pressure dispersive X-ray diffraction [7] and optical interferometry [8] to chart out the high density phase diagram, neutron Compton scattering [9] to determine the single particle kinetic energies, helium cluster luminescence spectroscopy [10], and inelastic X-ray scattering spectroscopy to study the electronic [11,12] and vibrational [13] excitations at different densities.…”

Impuriton-Phonon Quasiparticles Possibility and Rapid Dissolution of 3He Inclusions in 4He Crystal

“…The longitudinal velocity of sound c l = 400 ÷ 600m/s [1] depends on the pressure and the 4 He crystal orientation. In the case of quantization of the acoustic field the phonons energy has the form…”

“…In [16,17,18] interaction between vacancions describes the local variation of the 1 We neglect their own volume of the helium atom (R kinetic energy of the lattice vibrations due to the presence of vacancies. This kind of interaction is to be written for the fixed defects.…”

“…Here c ik are components of the elastic moduli tensor λ iklm in Voigt notation accounting for the crystal symmetry [20], and c 55 = c 44 9 (cm/s) 2 according to [1] and A hex = A hcp = 1.481. For comparison, we have A cub = A bcc = 23.6 in solid bcc 3 He at a molar volume of 21.64 cm 3 /mole [1]. Consequently, the phase hcp 4 He is close to isotropic.…”