Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 30: Matter At Low Temperature: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 1

TT 30.12: Vortrag

Mittwoch, 28. März 2012, 18:30–18:45, H 3005

Interaction of helium-3 impurities with point defects and deformation fileds in solid helium-4. — •Yaroslav Lutsyshyn — Institut für Physik, Universität Rostock, 18051 Rostock, Germany

Interaction between defects and impurities is widely believed to be at the root of a wide range of effects which had been observed in recent years in hcp solid helium-4. In particular, several theories place special role on the dislocation network pinning by helium-3 impurities.

We will report quantum Monte Carlo simulations of a helium-3 impurity in crystalline helium-4. Calculations are performed with the diffusion Monte Carlo method. This is a first principles approach which allows to obtain exact ground state of many-body bosonic systems. The results show that while vacancies are attracted to the impurity, the vacancy-He3 pair is not bound at low density. Additional impurity properties are extracted by simulating it in a strained crystal. Motion in the elastic deformation field can be used to describe the long-range interaction of helium-3 with various lattice defects, especially the dislocation lines.