Quantum spin liquid is a new quantum phase of matter in which a two-dimensional magnetic insulator material is induced by quantum fluctuation and material's frustrated geometry at low temperatures. Due to the long-range quantum entanglement derived from low temperature, the low energy excitation of the system exhibits typical features of fractionation and has the statistical properties beyond fermions and bosons. The most typical example of such fractionalized excitation is the fractionally charged excitations in the fractional quantum Hall states found in the 1980s. Due to the singular statistical properties of low energy excitation, the quantum spin liquid state is an important material basis for the realization of topological quantum computation in the future.
In the past decade, a series of possible spin liquid materials werereported experimentally. Inelastic neutron scattering became an important means of characterizing the fractionalized excitations in spin liquid materials especially in recent years. Due to the fractionalization of the excitation, the typical peak structure could no longer be observed in non-elastic neutron scattering spectrum. A more important result of those experiments was the measurement of the kagome antiferromagnet herbertsmithite, which is one of the most promising spin-liquid candidates. However, the lack of theoretical understanding of the dynamic properties of the corresponding kagome spin model resulted in an incomplete understanding of the experimental results.
In response to this problem, Professor Gong Shoushu from the School of Physics of Beihang University, Professor Zhu Wei of Beihang’s long-term partner Westlake Institute for Advanced Study, and Professor Sheng Dongning of California State University have togetherstudied the dynamic structural factors of the kagame spin system, using the large-scale density-matrix renormalization-group method. The current numerical results, which are so far the largest in size and highest in precision, show that the theoretical calculations and the experimental observations are highly consistent, indicating that the experimental results do support the ground state of Herbertsmithite as a gapless spin-liquid phase. They also broaden the thinking in understanding the inelastic neutron scattering features of other materials.
Figure: Comparison between the inelastic neutron scattering spectrum of spin liquid material Herbertsmithite and numerical results of the dynamic structural factor of kagome Heisenberg spin system.
The related results are published inProceedings of the National Academy of Sciences of the United States of America(PNAS) , titled “Spinon Fractionalization from Dynamic Structure Factor of Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice".
This work is funded by the Hundred Excellent Talents Project and the Top-Notch Youth Talents Project of Beihang University.
The research article is available at: