# Frustrated quantum Heisenberg double-tetrahedral and octahedral chains at high magnetic fields

## TL;DR

This paper studies frustrated quantum spin chains with flat magnon bands under high magnetic fields, developing effective models and validating them through numerical methods to understand their magnetic properties.

## Contribution

It introduces effective descriptions for frustrated Heisenberg chains with flat bands using localized magnons and confirms their accuracy via numerical simulations.

## Key findings

- Effective models accurately describe magnetization behavior.
- Numerical results match predictions of the localized magnons approach.
- High-field specific heat exhibits characteristic features of flat band systems.

## Abstract

We consider the spin-1/2 antiferromagnetic Heisenberg model on two one-dimensional frustrated lattices, double-tetrahedral chain and octahedral chain, with almost dispersionless (flat) lowest magnon band in a strong magnetic field. Using the localized magnons picture, we construct an effective description of the one-dimensional chains with triangle and square traps within the strong coupling approximation. We perform extensive exact diagonalization and density matrix renormalization group calculations to check the validity of the obtained effective Hamiltonians by comparison with the initial models with special focus on the magnetization and specific heat at high magnetic fields.