Hong Kong University physicists unveil new quantum state
Researchers at University of Hong Kong in collaboration with the Chinese Academy of Sciences and J-PARC Japan have uncovered a novel quantum state known as “Dirac spin liquid.” This groundbreaking discovery, published in Nature Physics, reveals the existence of Dirac spinons in a material called YCu3-Br, which features a kagome lattice structure.
Dirac spinons are quasiparticles that exhibit a linear dispersion relation between energy and momentum, similar to Dirac particles in high-energy physics and Dirac electrons in graphene. Despite being theorised for generations, these spin-½ charge-neutral quasiparticles had not been observed in quantum magnets until now.
Theoretical physicists Dr Chengkang Zhou and Professor Zi Yang Meng from the University of Hong Kong along with experimentalists Zhenyuan Zeng and Professor Shiliang Li at the Institute of Physics of the Chinese Academy of Sciences in Beijing and Professor Kenji Nakajima of J-PARC in Japan used inelastic neutron scattering to probe the spin excitations of YCu3-Br. By assembling approximately 5,000 single crystals, they overcame significant experimental challenges and observed conical spin continuum patterns characteristic of Dirac spinons.
This discovery not only advances the fundamental understanding of condensed matter physics but also opens new avenues for practical applications. The highly entangled quantum material could potentially be used in developing quantum computers, much like silicon has been used over the past half-century.
The study was supported by the Ministry of Science and Technology of China, the Chinese Academy of Sciences, and the Hong Kong Research Grants Council. Theoretical calculations were performed using Hong Kong University’s High-Performance Computing Platform and Beijing Paratera Tech Corp Ltd.
For more details, visit the Hong Kong University Faculty of Science website or access the full paper in Nature Physics.