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TT: Fachverband Tiefe Temperaturen

TT 47: Frustrated Magnets II (joint session MA/TT)

TT 47.6: Talk

Wednesday, March 11, 2026, 10:45–11:00, POT/0361

Magnetization plateaus, spin-canted orders and field-induced transitions in a spin-1/2 Heisenberg antiferromagnet on a distorted diamond-decorated honeycomb lattice — •Katarina Karlova and Jozef Strecka — Pavol Jozef Safarik University in Kosice, Slovakia

We investigate the spin-1/2 Heisenberg antiferromagnet on a distorted diamond-decorated honeycomb lattice in an external magnetic field. Using density-matrix renormalization group, sign-problem-free quantum Monte Carlo, exact diagonalization, and an effective lattice-gas approach based on localized-magnon physics, we determine the ground-state phase diagram and analyze the finite-temperature magnetization process.

The model hosts a rich variety of frustration-induced quantum phases, including Lieb-Mattis ferrimagnetic states, spin-canted regimes, monomer-dimer and dimer-tetramer phases, and dimensional-crossover states with 0D or 1D character. Depending on the lattice distortion, we identify robust magnetization plateaus at 0, 1/4, 1/2, and 3/4 of the saturation value, originating from competing local singlet clusters, composite spins, and flat-band localized magnons. Finite-temperature QMC data show how thermal fluctuations progressively smear the plateau structure, while the effective lattice-gas description reliably captures the corresponding low-temperature trends.

Funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V04-00403.

Keywords: Frustrated quantum magnetism; Heisenberg antiferromagnet; Magnetization plateaus; Localized magnons; Sign-problem-free Quantum Monte Carlo