We study the coexistence of the spin-polarized current and the spin accumulation in a three-terminal quantum ring structure, in which two quantum dots (QDs) are inserted in one arm of the ring and the Rashba spin-orbit interaction (RSOI) exists in the other. We find that by properly adjusting the applied voltages in the three leads, the RSOI-induced phase factor and the parameters relevant to the QDs, the spin-polarization efficiency in the leads can achieve either 100% or infinite, and the electrons of the same or different spin directions can accumulate in the two dots, respectively. The manipulation of the electron spin in the present device relies on the RSOI and the electric fields, thus making it realizable with the currently existing technologies.

A naked cyclo-N5 – salt has yet to be recovered to ambient conditions, precluding its application as a high-energy density material for explosive or propulsion applications. Here, we suggest a simple route for the synthesis of a metal cyclo-N5 – salt via compressing CuN6. Using first-principles calculations with structural search, we predict a CuN5 compound with a cyclo-N5 – anion that is energetically favorite in the pressure range of 50–100 GPa. At ambient conditions, CuN5 comprises alternant-connected cyclo-N5 – anions and Cu+ ions, forming a zigzag chain. The copper cyclo-N5 – salt is thermodynamically stable with a 2.5 eV band gap at ambient conditions. Further analysis of electronic properties reveals that the Cu atoms not only contribute electrons to change the bonding state of N5 rings but also use empty outer-shell orbitals to accommodate lone pair electrons of N atoms, forming coordinate bonds to stabilize the system. This expands the known cyclo-N5 – salt and indicates a simple route to its synthesis.

First-principles calculations and Boltzmann transport theory have been combined to comparatively investigate the band structure, phonon spectrum, lattice thermal conductivity, and the transport properties of the β-bismuth monolayer and bulk Bi.

A new type of spin-orbit magnetoresistance effect is observed in Cu/YIG with interface decorated with nanosize Pt islands.

No abstract

We report measurements of in-plane field magnetoresistivity of the two-dimensional electrons in two Si/ SiGe quantum wells with different disorder strength at 20 mK. For both samples, the ratio of the saturation resistivity in the high magnetic field to the zero-field resistivity was approximately constant in the high-density limit. In the metallic to insulating transition ͑MIT͒ regime, it is strongly enhanced and appears diverging as the electron density approaches a sample-dependent characteristic density n ‫ء‬ . n ‫ء‬ is below n c , the critical density of MIT at which the temperature dependence of resistivity changes sign. Disorder is believed to play an important role in this phenomenon. Furthermore, the field at which the magnetoresistivity saturates appears to extrapolate to zero, suggesting that ferromagnetic instability does not occur in Si/SiGe, at least down to n ϳ 0.3 ϫ 10 11 / cm 2 .Almost 15 years ago, a metallic to insulating transition ͑MIT͒ in conductivity was observed in high-mobility twodimensional electron systems ͑2DESs͒ realized in Si metaloxide-semiconductor field-effect transistors ͑Si MOSFETs͒. 1 Extensive studies have since been carried out to understand the nature of this transition. To date, there is still no unequivocal explanation for the observation and many issues remain unresolved. One example is the large response of the 2DES metallic conductivity to an in-plane magnetic field ͑B ip ͒. It was observed that the in-plane magnetoresistivity ͑B ip ͒ first increases as B ip 2 at low B ip . After a characteristic magnetic field B s , which has been identified as the full spinpolarization magnetic field for the 2DES, 2 the in-plane magnetoresistivity saturates to a constant value. In general, the enhancement of ͑B ip ͒ is due to the reduction in screening of charged impurities in a Fermi liquid caused by the loss of spin degeneracy. Depending on the nature of the disorder, i.e., the background impurity scattering vs the remote ionized impurity scattering, an enhancement ratio R ip ϵ ͑B ip Ͼ B s ͒ / ͑B ip =0͒ of 4 or ϳ1.2 is expected, respectively. 3-5 However, in most measurements in Si MOSFETs, this enhancement ratio is much larger up to several orders of magnitude when the electron density ͑n͒ is close to the critical density n c , at which the temperature dependence of resistivity changes sign. It remains unclear whether this colossal enhancement is simply a disorder effect or is related to the strong electron-electron interaction. Besides the enhancement ratio, B s is also controversial. In Ref. 6, Shashkin et al. showed that B s was linear with n and, by extrapolation, vanished at n c . This vanishing B s was then taken as evidence of a ferromagnetic instability in 2DES at n c . Later, however, this interpretation was criticized. 7Recently in the 2DES realized in Si/SiGe quantum wells, which experiences much weaker disorder and has higher mobility than in Si MOSFETs, very different results were obtained. 8 It was found that the resistivity enhancement ratio R ip in in-plane magneti...

We study the properties of the heat flow generated by electric current in a quantum dot (QD) molecular sandwiched between two ferromagnetic leads. The heat is exchanged between the QD and the phonon reservoir coupled to it. We find that when the leads' magnetic moments are in parallel configuration, the total heat generation is independent on the leads' spin-polarization regardless of the magnitude of the intradot Coulomb interaction. This behavior is similar to that of the electronic current. In the antiparallel configuration, however, the influences of the leads' ferromagnetism on the heat generation are quite different from those on the electric current. Under the conditions of weak intradot Coulomb interaction and small bias voltage, the heat generation is monotonously suppressed by increasing leads' spin-polarization. Whereas for sufficient large intradot Coulomb interaction and bias voltage, the heat generation shows non-monotonous behavior due to the electron-phonon interaction and the spin accumulation induced on the dot. Furthermore, the magnitude of the negative differential of the heat generation previously found in a QD connected to nonmagnetic leads can be weakened by the increase of the spin-polarization of the ferromagnetic leads.

Despite the ability of microbubble contrast agents to improve ultrasound diagnostic performance, their application potential is limited due to low stability, fast clearance, and poor tissue permeation. This study presents a promising nanosized phase‐changeable erythrocyte (Sonocyte), composed of liposomal dodecafluoropentane coated with multilayered red blood cell membranes (RBCm), for improving ultrasound assessments. Sonocyte is the first RBCm‐functionalized ultrasound contrast agent with uniform nanosized morphology, and exhibits good stability, systemic circulation, target‐tissue accumulation, and even ultrasound‐responsive phase transition, thereby satisfying the inherent requirement of ultrasound imaging. It is identified that Sonocyte displays similar sensitivity as microbubble SonoVue, a clinical ultrasound contrast agent, for effectively detecting normal parenchyma and hepatic necrosis. Importantly, compared with SonoVue lacking of ability to detect tumors, Sonocyte can identify tumors with high sensitivity and specificity due to superior tumor accumulation and penetration. Therefore, Sonocyte exhibits superior capabilities over SonoVue, endowing with a great clinical application potential.