Ferroelectric Controlled Spin Texture in Two-Dimensional NbOI_(2)Monolayer

The persistent spin helix(PSH)system is considered to have promising applications in energy-conservation spintronics because it supports an extraordinarily long spin lifetime of carriers.Here,we predict that the existence of PSH state in two-dimensional(2 D)ferroelectric NbOI_(2)monolayers.Our first-principles calculation results show that there exists Dresselhaus-type spin-orbit coupling(SOC)band splitting near the conduction-band minimum(CBM)of the NbOI_(2)monolayer.It is revealed that the spin splitting near CBM merely refers to out-of-plane spin configuration in the wave vector space,which gives rise to a long-lived PSH state that can be controlled by reversible ferroelectric polarization.We believe that the coupling characteristics of ferroelectric polarization and spin texture in NbOI_(2)provide a platform for the realization of fully electric controlled spintronic devices.

Exotic Dielectric Behaviors Induced by Pseudo-Spin Texture in Magnetic Twisted Bilayer

Twisted van der Waals bilayers provide an ideal platform to study the electron correlation in solids. Of particular interest is the 30° twisted bilayer honeycomb lattice system, which possesses an incommensurate moiré pattern,and uncommon electronic behaviors may appear due to the absence of phase coherence. Such a system is extremely sensitive to further twist and many intriguing phenomena will occur. Based on first-principles calculations we show that, for further twist near 30°, there could induce dramatically different dielectric behaviors of electron between left and right-twisted cases. Specifically, it is found that the left and right twists show suppressed and amplified dielectric response under vertical electric field, respectively. Further analysis demonstrate that such an exotic dielectric property can be attributed to the stacking dependent charge redistribution due to twist,which forms twist-dependent pseudospin textures. We will show that such pseudospin textures are robust under small electric field. As a result, for the right-twisted case, there is almost no electric dipole formation exceeding the monolayer thickness when the electric field is applied. Whereas for the left case, the system could even demonstrate negative susceptibility, i.e., the induced polarization is opposite to the applied field, which is very rare in the nature. Such findings not only enrich our understanding on moiré systems but also open an appealing route toward functional 2D materials design for electronic, optical and even energy storage devices.

Concepts of the half-valley-metal and quantum anomalous valley Hall effect

Valley,the energy extrema in the electronic band structure at momentum space,is regarded as a new degree of freedom of electrons,in addition to charge and spin.The studies focused on valley degree of freedom now form an emerging field of condensed-matter physics,i.e.,valleytronics,whose development is exactly following that of spintronics,which focuses on the spin degree of freedom.

Serum Copeptin and In-Hospital Major Adverse Events after Head Trauma: A Multicenter Study

Background: Copeptin is a biomarker for brain injury. However,it is unclear whether it is discriminative regarding in-hospital major adverse events (IMAEs),including acute lung injury,acute traumatic coagulopathy,progressive hemorrhagic injury and post-traumatic cerebral infarction,in patients with traumatic brain injury (TBI). This study was aimed at investigating the relationship between the serum copeptin level and occurrences of IMAEs. Methods: In this multicenter observational study,we recruited 173 severe TBI patients and 173 healthy controls. Serum levels of copeptin,interleukin-6,tumor necrosis factor-alpha,C-reactive protein,myelin basic protein,glial fibrillary astrocyte protein,S100B,neuron-specific enolase,phosphorylated axonal neurofilament subunit H,tau protein and ubiquitin carboxyl-terminal hydrolase L1 were quantified using available enzyme-linked immunosorbent assays. Areas under the receiver operating characteristic curves (AUCs) were estimated to determine and compare their discriminatory ability for IMAEs. Results: Patients had dramatically elevated levels of the afore-mentioned biomarkers,as compared with controls. In the discrimination of IMAEs,serum copeptin had a significantly higher AUC than serum interleukin-6,tumor necrosis factor-alpha and C-reactive protein and its AUC was similar to that of the Glasgow coma scale (GCS) score and the other remaining biomarkers mentioned above. Except copeptin,no other biomarkers could significantly improve the AUC of the GCS score. Conclusion: Serum copeptin levels combined with the GCS score might aid in discriminating IMAEs following TBI.