Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 14: 2D Materials: Session II (joint session DS/CPP/HL)

HL 14.9: Talk

Tuesday, March 13, 2018, 11:45–12:00, H 2032

Elasticity theory for two dimensional systems at finite temperatures — •Johannes Häring and Matthias Fuchs — FB Physik, Universität Konstanz, 78457 Konstanz, Germany

According to the Mermin-Wagner theorem many two dimensional systems only exhibit quasi-long-range order. Recently, we developed an elasticity theory for crystals with point defects and applied it to the defect rich cluster crystal [1]. The theory is able to handle long-range translational order. Now we present a method which includes quasi-long-range order.

Furthermore, orientational degrees of freedom are considered as well. As an example results of the helicity modulus and dynamical matrix of the two dimensional XY model are presented. Temperatures range between zero and the Kosterlitz-Thouless transition.

Finally, the influence of topological defects like vortices is discussed.

[1] J.M. Häring, C. Walz, G. Szamel, and M. Fuchs, Phys. Rev. B 92, 184103 (2015)