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Using first-principles calculations based on density-functional theory, this paper investigates the electronic structure and magnetic properties of the Heusler alloy Mn2LiGe bulk and its (001) surfaces. The Mn2LiGe bulk is demonstrated to be inverse Heusler alloy with space group of F43m and lattice constant of 5. 87 Å. A direct band gap with a width of 1. 1 eV near the Fermi surface of the spin-down channel is detected. The Mn2LiGe bulk possesses stable half-metallic and magnetism in the lattice constant range of 5. 55 - 6. 33 Å. In addition, six different surface structures of Mn2LiGe are constructed in this paper. The first layer atoms on the surface undergo different displacements, increasing the surface roughness. Due to surface effects, the magnetic properties of atoms on the surface are different compared to those in the bulk. Both the MnA MnA and MnB MnB surface structures have the highest magnetic moments, while the LiLi and the GeGe surface structures have the lowest magnetic moments. Electronic structure calculations show that the half-metallic band gap present in the bulk is destroyed in all six surface structures and the spin polarization is weakened in varying degrees. Only the LiLi surface structure maintains up to 99. 9% of the surface spin polarization, making the surface an excellent prospect for applications in spintronic devices. [ABSTRACT FROM AUTHOR]

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Improving the Curie temperature of V3O4 is a key problem to the application of this semimetal material in semiconductor spintronics. In this paper, the mechanism of the effect of the Cr and Ce co-doping on the spin polarization is investigated using the first-principles calculations. The results reveal that, compared with ideal V3O4, Cr and Ce co-doping lowers the spin polarization degree and total magnetic moment. However, when Cr and Ce dopants both at A sites, both at B sites, as well as at B and A sites, the stability of ferromagnetic state and the Curie temperature are both increased. Cr and Ce dopants both at A sites can best improve the ferromagnetic state and the Curie temperature. This study provides the theoretical guidance and method for improving stability of ferromagnetic state and the Curie temperature of V3O4, which promotes the applications of half-metal V3O4 in spintronics. [ABSTRACT FROM AUTHOR]

Understanding the phase structures of strong interaction matter is an active frontier in nuclear physics research currently, and it will provide crucial insights into heavy-ion collision experiments as well as neutron star observations. Most studies in this area focus on the influence of extremely high temperatures and baryon densities on matter properties, especially pertaining to phase transitions such as the chiral symmetry breaking and color superconductivity. Recent experimental and theoretical studies reported that in non-central heavy-ion collisions, systems carry a large initial angular momentum that becomes very strong vorticity fields in the bulk fluid. This has thus introduced several new questions regarding the properties of strong interaction matter under vorticity fields, and have led to many novel results. Thermal field theory calculations based on rotating frame and mean-field approximation have been developed to study various phase transitions under rotation, such as chiral symmetry breaking, color superconductivity and superfluidity at high isospin asymmetry. The results have demonstrated important impacts of vorticity fields on the phase boundaries of these transitions, and have also revealed nontrivial new phase structures of strong interaction matter under rotation. A new dimension of the usual QCD phase diagram has been unveiled. The study of rotation-induced phase transition extends phase transition research to a broader space. There remain more unexplored issues that merit further study.

The electromagnetic and electronic properties of six atomic terminations CrCr-ScFe-T, ZrSb-ScSn-T, CrCr-ScSn-B, ZrSb-ScFe-B, CrCr-ScFe-V, and ZrSb-ScSn-V in complete Heusler alloy Cr2 ZrSb/Sc2 FeSn (100) heterojunction were systematically studied by first-principles calculation based on density functional theory. The results show that the interactions between the interface atoms causes the unevenness of the interface atomic layer, which leads to the increase of the mechanical mismatch rate of the interface layer. Compared with the high spin polarization in the bulk, the spin polarization of the heterojunction is destroyed to varying degrees. Fortunately, the termination ZrSb-ScFe-B retains a high spin polarization value and has a tunnel magnetoresistance of 429.29% at low temperature according to the Julliere model, indicating its potential application prospects in spintronic devices. [ABSTRACT FROM AUTHOR]

In this paper, the first principle method based on density functional theory is used to calculate the electronic structure, magnetic moment, and charge density and differential charge density of the thin film growth system whose epitaxial relation is CoSi (001)//MgO (001). The results show that when the lattice constants a and b of CoSi crystal are set as 0 .84224 nm and C =0.28135 nm, the energy of the system is the lowest and the most stable equilibrium state is reached. It can be seen from the spin polarization band diagram, total electron state density and fractal density that the guide band bottom and valence band top of the CoSi epitaxial film overlap significantly, thus showing the gold property and producing obvious spin cracking phenomenon near the Fermi level. The valence band top is mainly composed of THE 3d7 state electrons of Co, while the conduction band bottom is mainly composed of the 3p state electrons of Si. At the same time, it can be seen from the state density that the phenomenon of pseudo energy gap is generated. The Co-3d state electrons not only mainly contribute to the state density, but also are speculated to be the main factor for the magnetic generation of the film. According to the calculated Mulliken charge and charge density, electrons are transferred from Si to Co, and Co ACTS as the electron acceptor, forming an anti-bonding state between Co and Si, and forming a covalent bond structure between Co and Si. The CoSi under this epitaxial relationship is ferromagnetic and the total magnetic moment is 0.52 μB. [ABSTRACT FROM AUTHOR]

Due to its inherent size and surface effect, the ferroelectric properties of two-dimensional ferroelectrics are very different from those of traditional bulk ferroelectrics. So far, two-dimensional ferroelectrics have been reported to have many properties, including bulk photoelectric effect, piezoelectric/pyroelectric effect, valley polarization and spin polarization. These properties either depend on ferroelectric polarization or couple with it for electrical control, which makes 2 D ferroelectrics suitable for multi-functional nano devices. At present, the research of two-dimensional ferroelectrics in theory, experiment and application is accumulating. This study briefly introduces these theories and methods. Then, the intrinsic and extrinsic origins of two-dimensional ferroelectrics are summarized respectively. Finally, the existing problems and development prospects of two-dimensional ferroelectrics are discussed. [ABSTRACT FROM AUTHOR]