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AMO/QO SEMINAR SERIES


"Nuclear polarized phases of H atoms embedded in solid H2 films"


Dr. Vladimir Khmelenko
Texas A&M University

ABSTRACT 

We report on the experimental observation of two phases of hydrogen atoms in solid H2 films at temperatures 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 polarized phase undergoes a phase transition to the spontaneously polarized phase, which breaks down at 𝑇 ≈ 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.


Tuesday, March 19, 2019
IQSE Seminar Room, 12:00 Noon
(578 MPHY)


Institute for Quantum Science and Engineering
Texas A&M University

Pizza lunch to be served at 11:30 a.m.

Host: Dr. Marlan Scully