Huiya Li

Large magnetic moment of gadolinium substituted topological insulator: Bi1.98Gd0.02Se3

The crystal structure, electronic, and magnetic properties of Gadolinium (Gd) substituted Bi2Se3—represented by Bi1.98Gd0.02Se3—were investigated systematically by scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and superconducting quantum interference device. Gd dopants with valence of 3+ were mainly found to substitute Bi atoms. Each Gd3+ ion has a magnetic moment as large as ∼6.9μB in the bulk paramagnetic state.

Electronic structure of a superconducting topological insulator Sr-doped Bi2Se3

Using high-resolution angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, the atomic and low energy electronic structure of the Sr-doped superconducting topological insulators (SrxBi2Se3) was studied. Scanning tunneling microscopy shows that most of the Sr atoms are not in the van der Waals gap. After Sr doping, the Fermi level was found to move further upwards when compared with the parent compound Bi2Se3, which is consistent with the low carrier density in this system. The topological surface state was clearly observed, and the position of the Dirac point was determined in all doped samples. The surface state is well separated from the bulk conduction bands in the momentum space. The persistence of separated topological surface state combined with small Fermi energy makes this superconducting material a very promising candidate for the time reversal invariant topological superconductor.

Carriers dependence of the magnetic properties in magnetic topological insulator Sb1.95−xBixCr0.05Te3

Bulk carrier density and magnetic properties of Sb1.95−xBixCr0.05Te3 single crystals were studied. We found that the carrier density can be tuned by Bi substitution. Both the Curie temperature and magnetic moments are strongly related to the carrier density, which suggests the existence of intrinsic ferromagnetism in Cr-doped Sb2Te3 magnetic topological insulator that is very important for spin-related applications.

Convective effect on the microstructure evolution during a liquid-liquid decomposition

The microstructure evolution during a liquid-liquid phase transformation was calculated. The effect of convections on the microstructure development was investigated. The results demonstrate that the convective flow against the solidification direction causes an increase in the local nucleation rate. Convections lead to a more nonuniform distribution of the minority phase droplets (MPDs) in the melt. They cause an increase in the size of the largest MPDs and are against the obtaining of the immiscible alloys with a well dispersed microstructure.

Carrier density dependence of the magnetic properties in iron-doped Bi2Se3 topological insulator

The electronic and magnetic properties of iron-doped topological insulator Bi1.84−xFe0.16CaxSe3 single crystals were studied. By co-doping Fe and Ca atoms, ferromagnetic bulk states with different carrier density (from n-type to p-type) were obtained. Effective magnetic moments for each Fe atom was estimated as small as about 0.07μB. Magnetic and non-magnetic phases separation was observed in all samples. Our results suggest that the bulk ferromagnetism in Fe-doped Bi2Se3 is not intrinsic and regardless of carrier density.

Size dependent melting behaviors of nanocrystalline in particles embedded in amorphous matrix

The composites of In nanoparticles embedded in Al-based amorphous matrix were synthesized. As the content of In increases, the average size of In nanoparticles increases. The melting behaviors of embedded In nanoparticles were investigated, indicating that the melting temperature is suppressed, and the smaller the size is, the lower the melting temperature is. It is confirmed by comparing the differential scanning calorimetry curves with those of the size distribution. The size dependent melting behaviors of nanoparticles were discussed with the thermodynamic model.

Wetting behavior of molten In–Sn alloy on bulk amorphous and crystalline Cu40Zr44Al8Ag8

Using the sessile-drop method, the wettability of the molten In–Sn alloy on bulk amorphous and crystalline Cu40Zr44Al8Ag8 alloy was studied at different temperatures. It was found that the equilibrium contact angle of In–Sn alloy melt on bulk amorphous substrate was smaller than that of the crystalline one. An intermetallic compound existed at the interface of In–Sn alloy on amorphous Cu40Zr44Al8Ag8, while no intermediate reaction layer was formed at the interface of In–Sn alloy on crystalline Cu40Zr44Al8Ag8 in the temperature range studied.

Effects of quasicrystal formation on the crystallization of (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) metallic glasses

The crystallization behaviors of the (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17; at. %) metallic glasses are investigated under both the continuous heating and isothermal conditions by the differential scanning calorimetry. Quasicrystals are found in the crystallization products under both conditions by X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The evolution of the primary crystallization products of these alloys is discussed in detail. The effects of the increasing distortion energy of the icosahedral short-range order with the increasing Cu content in the(Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) alloys are found to be responsible for the evolution of the crystallization products. The isothermal crystallization kinetics deviates from the Johnson-Mehl-Avrami-Kolmogoroff (JMAK) model. A modified JMAK model with an impingement parameter is found to be suitable for the isothermal crystallization kinetic...