Thermoelectric response of spin polarization in Rashba spintronic systems

Motivated by the recent discovery of a strongly spin-orbit-coupled two-dimensional （2D） electron gas near the surface of Rashba semiconductors BiTeX （X = Cl, Br, I）, we calculate the thermoelectric responses of spin polarization in a 2D Rashba model. By self-consistently determining the energy- and band-dependent transport time, we present tion for elastic scattering. Using this solution, an exact solution of the linearized Boltzmann equa- we find a non-Edelstein electric-field-induced spin polarization that is linear in the Fermi energy EF when EF lies below the band crossing point. The spin polarization efficiency, which is the electric-field-induced spin polarization divided by the driven electric current, increases for smaller EF. We show that, as a function of EF, the temperature- gradient-induced spin polarization increases continuously to a saturation value when EF decreases below the band crossing point. As the temperature tends to zero, the temperature-gradient-induced spin polarization vanishes.

Experimental evidence of anomalously large superconducting gap on topological surface state of b-Bi2Pd film

Connate topological superconductor(TSC) combines topological surface states with nodeless superconductivity in a single material, achieving effective p-wave pairing without interface complication. By combining angle-resolved photoemission spectroscopy and in-situ molecular beam epitaxy, we studied the momentum-resolved superconductivity in b-Bi2 Pd film. We found that the superconducting gap of topological surface state(DTSS$ 3.8 meV) is anomalously enhanced from its bulk value(Db$ 0.8 meV). The ratio of 2 DTSS/kBTc$ 16.3, is substantially larger than the BCS value. By measuring b-Bi2 Pd bulk single crystal as a comparison, we clearly observed the upward-shift of chemical potential in the film. In addition, a concomitant increasing of surface weight on the topological surface state was revealed by our first principle calculation, suggesting that the Dirac-fermion-mediated parity mixing may cause this anomalous superconducting enhancement. Our results establish b-Bi2 Pd film as a unique case of connate TSCs with a highly enhanced topological superconducting gap, which may stabilize Majorana zero modes at a higher temperature.

Asymmetric ferromagnetic criticality in pyrochlore ferromagnet Lu2V2O7

We study the ferromagnetic criticality of the pyrochlore magnet Lu2 V2 O7 at the ferromagnetic transition TC% 70 K from the isotherms of magnetization MeHT via an iteration process and the Kouvel-Fisher method. The critical exponents associated with the transition are determined: b = 0.32(1), c = 1.41(1),and d ? 5:38. The validity of these critical exponents is further verified by scaling all the MeHT data in the vicinity of TConto two universal curves in the plot of M=jejbversus H=jejbtc, where e ? T=TCà 1.The obtained b and c values show asymmetric behaviors on the T < TCand the T > TCsides, and are consistent with the predicted values of 3 D Ising and cubic universality classes, respectively. This makes Lu2 V2 O7 a rare example in which the critical behaviors associated with a ferromagnetic transition belong to different universality classes. We describe the observed criticality from the Ginzburg-Landau theory with the quartic cubic anisotropy that microscopically originates from the anti-symmetric Dzyaloshinskii-Moriya interaction as revealed by recent magnon thermal Hall effect and theoretical investigations.

Photolithography-free fabrication of photoresist-mold for rapid prototyping of microfluidic PDMS devices

Traditional soft lithography based PDMS device fabrication requires complex procedures carried out in a clean room. Herein, we report a photolithography-free method that rapidly produces PDMS devices in 30 min. By using a laser cutter to ablate a tape, a male photoresist mold can be obtained within 5 min by a simple heating-step, which offers significant superiority over currently used photolithographybased method. Since it requires minimal energy to cut the tape, our fabrication strategy shows good resolution(~ 100 μm) and high throughput. Furthermore, the micro-mold height can be easily controlled by changing the tape types and layers. As a proof-of-concept, we demonstrated that the fabricated PDMS devices are compatible with biochemical reactions such as quenching reaction of KI to fluorescein and cell culture/staining. Collectively, our strategy shows advantages of low input, simple operation procedure and short fabrication time, therefore we believe this photolithography-free method could serve as a promising way for rapid prototyping of PDMS devices and be widely used in general biochemical laboratories.

Laser-induced topology optimized amorphous nanostructure and corrosion electrochemistry of supersonically deposited Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) HEA coating based on AIMD

A novel Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) high-entropy alloy(HEA)coating was irradiated to optimize its internal structure via laser after supersonic particle deposition(SPD).Owing to the high energy density of the laser and large temperature gradient,the crystallization process of the molecules and atoms in the coating was restrained and supercooling occurred.Experimental results showed that a considerable number of nano-crystal grains precipitated and amorphous structures were formed because of the random orientation of the crystals.The baseline of differential scanning calorimetry scans obtained for the coating started to shift at the Tg of 939.37℃ and a step was observed.Multiple dispersion peaks and lattice fringes indicated that the nucleation of the irradiated laser-induced topology optimized(LTO)coating was incomplete.The laser-induced topology optimizing treatment led to quasi-isotropy in the SPD coating.Furthermore,the LTO coating exhibited a residual stress of 18.4 MPa,stress-strain response,and fatigue limit of 265 MPa.Hence,the LTO coating exhibited higher performance than the unirradiated SPD coating.The Nyquist and Bode electrochemical impedance spectra of the LTO coating,including two relaxation processes,indicated that the corrosion process steadily recovered to the equilibrium state.This implies that the uniform oxidation passivation layer on the surface of the LTO coating insulated the material from the corrosive medium,protecting the substrate from further corrosion,thus enhancing the structural security of the material for use in super-intense laser facility applications.