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  • Decorative image Prof Daw-Wei Wang (Deputy director, TG7 and a professor of NTHU) and Prof. Chung-Yu Mou (TG8, professor of NTHU) have published in Phys. Rev. Letter (Editor's Suggestion) on a new system for metallic quantum solid in Rydberg atoms.  They examine possible low-temperature phases of a repulsively Rydberg-dressed Fermi gas in a three-dimensional free space. It is shown that the collective density excitations develop a roton minimum, which is softened at a wave vector smaller than the Fermi wave vector when the particle density is above a critical value. The mean field calculation shows that, unlike the insulating density wave states often observed in conventional condensed matters, a self-assembled metallic density wave state emerges at low temperatures. In particular, the densit...Read More
  • Decorative imageThe quantum anomalous Hall (QAH) phase is a two-dimensional bulk ferromagnetic insulator with a nonzero Chern number in the presence of spin-orbit coupling (SOC) but in the absence of applied magnetic fields. Associated metallic chiral edge states host dissipationless current transport in electronic devices and thus promise great applications in low-power-consumption electronic and spintronic devices. This intriguing QAH phase has recently been observed in magnetic impurity-doped topological insulators, albeit, at extremely low temperatures. By first-principles density functional calculations, Guang-Yu Guo (Distinguished Center Scientist & Professor of NTU-Physics) and his collaborators recently demonstrated in a paper published in the Physical Review Letters[1] that layered rhodium ox...Read More
  • Decorative imageAlmost a decade ago, an anomaly was observed in neutron scattering experiment on the spin ice material Ho2Ti2O7, and the origin of this anomaly has so far eluded theorists. In a paper published in Phys. Rev. B 93, 180410(R), Prof. Ying-Jer Kao (Center Scientist, TG4 coordinator, Prof. of NTU) and his collaborators simulated the dipolar spin ice model by closely mimicking the experimental setup and found that the anomalous critical scattering is related to the selection of an ordered state, previously known as q=X state. Spin ice is a class of materials with a crystal structure called pyrochlore, which is composed of corner-sharing tetrahedra. The magnetic moments, or spins, are confined to pointing into or out of the center of the tetrahedron. Applying magnetic field along the three-fold ...Read More
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