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  • 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
  • Decorative imageProf. Yueh-Nan Chen (Dep. of Physics, NCKU, and Center Scientist of NCTS) and his student collaborate with Prof. Yeong-Cherng Liang (professor of NCKU, TG6) published their recent works in Phys. Rev. Lett. on the topic of Device-independent quantification of quantum steerability. They introduce the concept of assemblage moment matrices and demonstrate how it can be used for quantum states and measurements characterization in a device-independent manner, i.e., without invoking any assumption about the measurement nor the preparation device. In addition, by proving a quantitative relationship between steering robustness and the recently introduced incompatibility robustness, their approach also allows for a device-independent quantification of the incompatibility between various measure...Read More
  • Decorative imageProf. Chung-Yu Mou, Prof. Chung-Hou Chung (TG8) and collaborators published their research in Phys. Rev. Lett. on April 29, 2016 on theoretical realization of fermionic finite-temperature Dirac points as critical points separating two topological phases in a Kondo lattice. The underlying Dirac point is central to the profound physics manifested in a wide class of materials. However, it is often difficult to drive a system with Dirac points across the massless fermionic critical point. Here by exploiting screening of local moments under spin-orbit interactions in a Kondo lattice, they show that below the Kondo temperature, the Kondo lattice undergoes a topological transition from a strong topological insulator (STI) to a weak topological insulator (WTI) at a finite temperature TD. At&n...Read More
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