Search

Liquid–liquid phase transitions hold a unique and profound significance within condensed matter physics. These transitions, while conceptually intriguing, often pose formidable computational challenges. However, recent advances in neural network (NN) potentials offer a promising avenue to effectively address these challenges. In this paper, we delve into the structural transitions of liquid CdTe, CdS, and their alloy systems using molecular dynamics simulations, harnessing the power of an NN potential named LaspNN. Our investigations encompass both pressure and temperature effects. Through our simulations, we uncover three primary liquid structures around melting points that emerge as pressure increases: tetrahedral, rock salt, and close-packed structures, which greatly resemble those of solid states. In the high-temperature regime, we observe the formation of Te chains and S dimers, providing a deeper understanding of the liquid's atomic arrangements. When examining CdSxTe1−x alloys, our findings indicate that a small substitution of S by Te atoms for S-rich alloys (x > 0.5) exhibits a structural transition much different from CdS, while a large substitution of Te by S atoms for Te-rich alloys (x < 0.5) barely exhibits a structural transition similar to CdTe. We construct a schematic diagram for liquid alloys that considers both temperature and pressure, providing a comprehensive overview of the alloy system's behavior. The local aggregation of Te atoms demonstrates a linear relationship with alloy composition x, whereas that of S atoms exhibits a nonlinear one, shedding light on the composition-dependent structural changes. [ABSTRACT FROM AUTHOR]

Defects play significant roles in spin-current-related physical processes in intrinsic ferromagnetic semiconductors (FMSs), which are great promise for spintronics applications. However, current defect calculation methods cannot be used to investigate charged defects in FMSs due to the spin polarization of both the charged defect states and ionized carriers, which is not well treated in current defect calculation methods. In order to solve this problem, we propose a spin-distinguishable charge correction (SDCC) method that uses spin-polarized band edge charge density instead of spin-unpolarized uniform background charge density as the compensating charge for charged defects. We apply our method to study the defect properties of CrI3 monolayer and find it can be doped n-type under the Cr-rich growth condition but difficult to be doped p-type. The SDCC method proposed here is generally suitable for all FMSs, which will be useful for the studies of defect properties of magnetic semiconductors. [ABSTRACT FROM AUTHOR]

Defects play significant roles in spin-current-related physical processes in intrinsic ferromagnetic semiconductors (FMSs), which are great promise for spintronics applications. However, current defect calculation methods cannot be used to investigate charged defects in FMSs due to the spin polarization of both the charged defect states and ionized carriers, which is not well treated in current defect calculation methods. In order to solve this problem, we propose a spin-distinguishable charge correction (SDCC) method that uses spin-polarized band edge charge density instead of spin-unpolarized uniform background charge density as the compensating charge for charged defects. We apply our method to study the defect properties of CrI3 monolayer and find it can be doped n-type under the Cr-rich growth condition but difficult to be doped p-type. The SDCC method proposed here is generally suitable for all FMSs, which will be useful for the studies of defect properties of magnetic semiconductors. [ABSTRACT FROM AUTHOR]

Aim: Stent placements for the treatment of complex internal carotid bifurcation aneurysms are not well documented yet. In this article, we reported a series of 16 such cases to evaluate the feasibility, safety and effectiveness of stent placement for these particular lesions., Material and Methods: Between June 2001 and August 2011, 16 patients with 16 ICA bifurcation aneurysms were treated by stent assisted coiling at our institution. Their clinical data, treatment results and follow-up were retrospectively collected and analyzed., Results: Sixteen stents, including 10 Enterprise, 4 Neuroform, 1 Solitaire and 1 one balloon-mounted coronary stent (BX), were successfully deployed in this series. Immediate angiogram showed complete occlusion in 5, neck remnant in 2 and residual sac in 9. No procedure-related complication occurred. Angiographic follow-up results (mean, 12.1 months) were available in 15 patients, 9 of the aneurysms were cured, 1 was improved, 3 were stable, 2 were recanalized, and 1 was retreated. Clinical follow-up (mean, 28.6 months) of all 16 patients demonstrated no neurologic deterioration or rebleeding., Conclusion: Our result suggests that stent placement for the treatment of complex ICA bifurcation aneurysms is feasible and safe. However, its efficacy should be further evaluated by larger case series and more adequate follow-up.