SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 9: Cooperative Phenomena: Spin Structures and Magnetic Phase Transitions

MA 9.1: Vortrag

Montag, 27. März 2023, 15:00–15:15, HSZ 401

Spin functional renormalization group for dimerized quantum spin systems — Andreas Rückriegel, •Jonas Arnold, Raphael Goll, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Straße 1, 60438 Frankfurt, Germany

We investigate dimerized quantum spin systems using the spin functional renormalization group approach proposed by Krieg and Kopietz [Phys. Rev. B 99, 060403(R) (2019)] which directly focuses on the physical spin correlation functions and avoids the representation of the spins in terms of fermionic or bosonic auxiliary operators. Starting from decoupled dimers as initial condition for the renormalization group flow equations, we obtain the spectrum of the triplet excitations as well as the magnetization in the quantum paramagnetic, ferromagnetic, and thermally disordered phases at all temperatures. Moreover, we compute the full phase diagram of a weakly coupled dimerized spin system in three dimensions, including the correct mean field critical exponents at the two quantum critical points.