Formation of Nuclear-Polarized Phases of H Atoms Embedded in Solid H-2 Films



: Sheludiakov S, McColgan PT, Lee DM, Khmelenko VV, Järvinen J, Ahokas J, Vasiliev S

Publisher: AMER PHYSICAL SOC

: 2019

: Physical Review Letters

: PHYSICAL REVIEW LETTERS

: PHYS REV LETT

: ARTN 225301

: 122

: 22

: 5

: 0031-9007

: 1079-7114

DOI: https://doi.org/10.1103/PhysRevLett.122.225301

: https://research.utu.fi/converis/portal/detail/Publication/41276084


We report on an experimental observation of two phases of hydrogen atoms in solid H-2 films at temperatures of 0.1-0.8 K, characterized by a large enhancement of the nuclear spin polarization compared to that given by Boltzmann statistics (p = 0.15 at T = 0.15 K). The first phase with p = 0.35(5) is formed spontaneously during sample storage in a high magnetic field (B = 4.6 T). The second phase with an even higher nuclear polarization, p = 0.75(7), can be achieved at T <= 0.55 K by repeating sequences of dynamic nuclear polarization followed by a system relaxation. Upon warming through the range 0.55-0.65 K, the highly nuclear-polarized phase undergoes a phase transition to the spontaneously polarized phase which breaks down at T similar or equal to 0.8 K, and the nuclear polarization gradually converges to the Boltzmann distribution. We discuss possible scenarios for explaining the nature of the observed phenomena.

Last updated on 2024-26-11 at 20:28