Focusing RKKY interaction by graphene P-N junction

The carrier-mediated RKKY interaction between local spins plays an important role for the application of magnetically doped graphene in spintronics and quantum computation. Previous studies largely concentrate on the influence of electronic states of uniform systems on the RKKY interaction. Here we reveal a very different way to manipulate the RKKY interaction by showing that the anomalous focusing - a well-known electron optics phenomenon in graphene P-N junctions - can be utilized to refocus the massless Dirac electrons emanating from one local spin to the other local spin. This gives rise to rich spatial interference patterns and symmetry-protected non-oscillatory RKKY interaction with a strongly enhanced magnitude. It may provide a new way to engineer the long-range spin-spin interaction in graphene.Comment: 9 pages, 4 figure

Superfluid and magnetic states of an ultracold Bose gas with synthetic three-dimensional spin-orbit coupling in an optical lattice

We study ultracold bosonic atoms with the synthetic three-dimensional spin-orbit (SO) coupling in a cubic optical lattice. In the superfluidity phase, the lowest energy band exhibits one, two or four pairs of degenerate single-particle ground states depending on the SO-coupling strengths, which can give rise to the condensate states with spin-stripes for the weak atomic interactions. In the deep Mott-insulator regime, the effective spin Hamiltonian of the system combines three-dimensional Heisenberg exchange interactions, anisotropy interactions and Dzyaloshinskii-Moriya interactions. Based on Monte Carlo simulations, we numerically demonstrate that the resulting Hamiltonian with an additional Zeeman field has a rich phase diagram with spiral, stripe, vortex crystal, and especially Skyrmion crystal spin-textures in each xy-plane layer. The obtained Skyrmion crystals can be tunable with square and hexagonal symmetries in a columnar manner along the z axis, and moreover are stable against the inter-layer spin-spin interactions in a large parameter region.Comment: 9 pages, 4 figures; title modified, references and discussions added; accepted by PR

The electronic structure of intrinsic magnetic topological insulator MnBi2Te4 quantum wires

The ferromagnetic and antiferromagnetic nanostructure are crucial for fundamental spintronics devices, motivated by its potential application in spintronics, we theoretically investigate the electronic structure of the ferromagnetic and antiferromagnetic phases of the cylindrical intrinsically magnetic topological insulator $\mathrm{MnBi_{2}Te_{4}}$ quantum wires for both cases. We demonstrate that a few surface states exist between the bulk band gap in the ferromagnetic phase, with only one spin branch. In the antiferromagnetic phase, we show that three coexistent states exist between the energy gaps of the quantum wires

Cynodon dactylon (L) Pers (Poaceae) root extract induces apoptotic cell death via the cyclin D1 pathway in human nasopharyngeal carcinoma cells in vitro and in vivo

Purpose: To investigate the activity of Cynodon dactylon root extract as a potential anticancer agent.Methods: Human nasopharyngeal carcinoma HNK-1 cells were treated with ethanol extract of C. dactylon roots. After treatment with C. dactylon root extract, cells were assessed for their cytotoxicity, metabolic status, apoptosis and cell cycle progression. The anticancer activity of the extract was also determined in vivo using a mouse model.Results: C. dactylon extract exhibited significant cytotoxicity and arrested cell cycle in HNK-1 cells in a dose-dependent manner. Fluorescence-activated cell sorting (FACS) data revealed that it also induced apoptotic cell death. Rb phosphorylation and mRNA levels of cyclin E were significantly reduced. Moreover, C. dactylon extract caused a significant reduction in tumor size and volume in vivo.Conclusion: C. dactylon root extract induces apoptosis in nasopharyngeal cancer cells via cyclin D1 pathway and inhibits tumor growth in vivo.Keywords: Cynodon dactylon, Anticancer, Cyclin D1 pathway, Apoptosis, Nasopharyngeal carcinom