Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi2Te4 thin films.

The intrinsic magnetic topological insulator MnBi2Te4 provides a feasible pathway to the high-temperature quantum anomalous Hall (QAH) effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4 thin flakes, it remains a big challenge to achieve molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4 thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4 and to find a way out of the big difficulty in obtaining MnBi2Te4 samples showing quantized transport properties.

Quadruple fenestration aortic stent implantation combined with unilateral IBE and internal iliac artery stent implantation for complex abdominal aortic aneurysm: one case report.

An abdominal aortic aneurysm is a frequently encountered clinical condition, which necessitates prompt and effective remediation to avoid rupture. Surgeons must meticulously select an appropriate method of repair and assess the long-term surgical prognosis when dealing with patients with complex abdominal aortic aneurysms. In this case report, a 74-year-old man was hospitalized due to acute abdominal pain. Upon further examination, it was discovered that he was suffering from a complex abdominal aortic aneurysm. The thoracoabdominal aorta CTA showed that the aneurysm involved both renal arteries, the part below the kidney was severely twisted, the neck of the aneurysm was short, and it was accompanied by bilateral common iliac and internal iliac aneurysms, and there were considerable thrombus attached to the vessel wall. In this case, our team used 3D technology to simulate the spatial structure of the aneurysm and comprehensively evaluate the patient's condition. Ultimately, we decided to perform a quadruple fenestration aortic stent implantation and endovascular repair of aortic aneurysm, combined with right IBE and internal iliac artery stent implantation, right internal iliac artery reconstruction, and left internal iliac artery aneurysm embolization on this patient. This is an innovative surgical method. The operation was successful and the patient recovered well after the operation.

Controlling the Zero Hall Plateau in a Quantum Anomalous Hall Insulator by In-Plane Magnetic Field.

We investigate the quantum anomalous Hall plateau transition in the presence of independent out-of-plane and in-plane magnetic fields. The perpendicular coercive field, zero Hall plateau width, and peak resistance value can all be systematically controlled by the in-plane magnetic field. The traces taken at various fields almost collapse into a single curve when the field vector is renormalized to an angle as a geometric parameter. These results can be explained consistently by the competition between magnetic anisotropy and in-plane Zeeman field, and the close relationship between quantum transport and magnetic domain structure. The accurate control of zero Hall plateau facilitates the search for chiral Majorana modes based on the quantum anomalous Hall system in proximity to a superconductor.

Zitterbewegung near new Dirac points in graphene superlattices.

New Dirac points may appear when periodic potentials are applied to graphene, and there are many interesting effects near them. Here we investigate the Zitterbewegung effect of fermions described by a Gaussian wave packet in graphene superlattice near these points. The Zitterbewegung near different Dirac points has similar characteristics, while fermions near new ones have different group velocities in both x- and y-direction, which causes the different properties of the Zitterbewegung near them. We also investigate the Zitterbewegung effect influenced by multi Dirac points, and get the evolution with changing potential. Our results suggest that graphene superlattice may provide an appropriate system to study the Zitterbewegung effect near new Dirac points experimentally.