Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 52: Quantum Magnets and Molecular Magnets (joint session TT/MA)

MA 52.2: Talk

Thursday, March 19, 2020, 15:30–15:45, HSZ 304

The power of typicality applied to magnetic molecules and low-dimensional quantum spin systems — •Jürgen Schnack — Universität Bielefeld, Fakultät für Physik

Molecular or low-dimensional quantum spin systems often prevent an exact calculation of their magnetic properties due to a prohibitively large size of the related Hilbert spaces. Typicality-based approaches such as the finite-temperature Lanczos method allow to investigate rather large systems with unprecedented accuracy. This way quantum critical as well as magnetocaloric properties of large cyclic clusters could be elucidated [1]. For the kagome lattice antiferromagnet it became possible to model a lattice of size N=42 (!) quasi exactly. This enabled us to study in particular that the low-lying density of singlet states moves up in energy contrary to common believe [2]. In addition, we could demonstrate for lattices up to 72 sites that magnon crystallization occurs slightly below the saturation field, an effect driven by the existance of flat energy bands [3].

[1] A. Baniodeh et al., npj Quantum Materials 3,10 (2018)

[2] J. Schnack, J. Schulenburg, J. Richter, Phys. Rev. B 98, 094423 (2018)

[3] J. Schnack, J. Schulenburg, A. Honecker, J. Richter, arXiv:1910.10448