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Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
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Dynamical Signatures of Quasiparticle Interactions in Quantum Spin Chains
Anna Keselman1, Leon Balents1,2, Oleg A Starykh3
1Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.
Physical Review Letters
|November 16, 2020
Summary
We investigated spin-1/2 chains and found that interactions create gaps in excitations and two-magnon bound states. These findings offer insights into quantum magnetism and condensed matter physics.
Area of Science:
- Condensed Matter Physics
- Quantum Magnetism
- Low-Dimensional Materials
Background:
- Antiferromagnetic spin-1/2 chains are fundamental models in quantum magnetism.
- Understanding excitation spectra under external fields is crucial for material properties.
Purpose of the Study:
- Investigate the transverse dynamical susceptibility of spin-1/2 chains with a longitudinal Zeeman field.
- Characterize the impact of spinon interactions and neighbor couplings on excitation gaps.
- Explore the emergence of bound states in the high magnetization regime.
Main Methods:
- Utilized numerically accurate, unbiased matrix-product-state techniques.
- Employed analytic approximations for theoretical insights.
- Analyzed the transverse dynamical susceptibility.
Main Results:
- Identified a nonzero gap in excitation branches at low momentum due to backscattering interactions in the gapless phase.
- Demonstrated the gap's dependence on second neighbor interactions, vanishing in a noninteracting spinon gas limit.
- Uncovered two-magnon bound states in the transverse susceptibility near magnetic saturation.
Conclusions:
- Spinon interactions significantly influence the low-energy spectrum of antiferromagnetic chains.
- The observed bound states generalize known phenomena in integrable systems.
- Provides a comprehensive understanding of excitation dynamics in spin chains.
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