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TT: Fachverband Tiefe Temperaturen

TT 33: Correlated Electrons: Method Development 1

TT 33.12: Vortrag

Mittwoch, 18. März 2020, 12:30–12:45, HSZ 201

Orientational order parameters for arbitrary quantum systems* — •Michael te Vrugt and Raphael Wittkowski — Institut für Theoretische Physik, Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany

The concept of quantum-mechanical nematic order, which is important in systems such as superconductors, is based on an analogy to classical liquid crystals, where order parameters are obtained through orientational expansions. We generalize this method to quantum mechanics based on an expansion of Wigner functions. This provides a systematic framework for the derivation of quantum order parameters, which unifies all known types of quantum orientational order into one framework and has a natural connection to the classical case. Moreover, new order parameters allow to find new orientational quantum phases. The method is demonstrated for Fermi liquids and spin systems. In addition, we construct new order parameters for molecular systems that cannot be properly described with the usual nematic tensors.
*Funded by the Deutsche Forschungsgemeinschaft (DFG) – WI 4170/3-1