Dynamic Correlations of Frustrated Quantum Spins from High-Temperature Expansion.

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Computational Physics

Background:

• The dynamic structure factor (DSF) is crucial for understanding quantum spin systems.
• Simulating DSF accurately is challenging for frustrated and high-dimensional models at intermediate temperatures.

Purpose of the Study:

• To develop an unbiased and accurate method for computing the DSF.
• To investigate the behavior of frustrated quantum spin models.
• To provide a benchmark for theoretical calculations.

Main Methods:

• A dynamic extension of the high-temperature expansion to frequency moments was employed.
• Calculations focused on nearest-neighbor Heisenberg models with spin lengths S=1/2 and S=1.
• The method was applied to frustrated two- and three-dimensional antiferromagnets.

Main Results:

• The study provides comprehensive benchmarks for the dynamic structure factor (DSF).
• New insights into the anomalous intermediate temperature regime of the S=1/2 triangular lattice model were obtained.
• The computed DSF successfully reproduced experimental measurements for the S=1 pyrochlore material NaCaNi_{2}F_{7}.

Conclusions:

• The developed method offers an accurate way to compute DSF for challenging quantum spin systems.
• The findings shed light on the complex behavior of frustrated magnetic models.
• An open-source implementation is provided for broader scientific use.