Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging (CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation - clusters. The method is unique for identifying the atomic locations with ångstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summaries the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI (UCEI). Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Manipulation of the valley degree of freedom provides a new path for quantum information technology, but the real intrinsic large valley-polarization materials are few reported up to date. Here, we perform first-principles calculations to predict a class of 2H-phase single layer (SL) materials Lu<jats:italic>X</jats:italic> <jats:sub>2</jats:sub> (<jats:italic>X</jats:italic>=Cl, Br, I) to be ideal candidates. SL-Lu<jats:italic>X</jats:italic> <jats:sub>2</jats:sub> are ferrovalley materials with a giant valley-polarization of 55~148 meV as a result of its large spin-orbital coupling (SOC) and intrinsic ferromagnetism (FM). The magnetic transition temperatures of SL-LuI<jats:sub>2</jats:sub> and SL-LuCl<jats:sub>2</jats:sub> are estimated to be 89~124K, with a sizable magnetic anisotropy with out-of-plane direction. Remarkably, the anomalous valley Hall effect (AVHE) can be controlled in SL-Lu<jats:italic>X</jats:italic> <jats:sub>2</jats:sub> when an external electric field is applied. Moreover, the intrinsic valley-polarization of SL-LuI<jats:sub>2</jats:sub> is highly robust for biaxial strain. These findings provide a promising ferrovalley material system for the experiment of valleytronics and the subsequent application.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Logic gates are fundamental structural components in all modern digital electronic devices. Here, nonequilibrium Green’s functions are incorporated with the density functional theory to verify the thermal spin transport features of the single-molecule spintronic devices constructed by a single molecule in series or parallel connected with graphene nanoribbons electrodes. Our calculations demonstrate that the electric field can manipulate the spin-polarized current. Then, a complete set of thermal spin molecular logic gates is proposed, including AND, OR, and NOT gates. The mentioned logic gates enable different designs of complex thermal spin molecular logic functions and facilitate the electric field control of thermal spin molecular devices.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recently, a Corbino-geometry Josephson junction (JJ) based on topological insulator has been proposed for hosting and braiding Majorana zero modes. As a first step to test this proposal, we successfully fabricated Corbino-geometry JJs on the surface of topological insulator Bi2Te3. Ac Josephson effect with fractional Shapiro steps was observed in the Corbino-geometry JJs while the flux in the junction area is quantized. By analyzing the experimental data using the resistively shunted Josephson junction model, we found that the Corbino-geometry JJs exhibit a highly transparent current-phase relation. The results suggest that Corbino-geometry JJs may provide a promising platform for studying Majorana-related physics.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic computing. In this work, we demonstrate the switching plasticity in Co/Gd ferrimagnetic multilayers where the binary states magnetization switching induced by spin-orbit toque can be tuned into a multistate one as decreasing the domain nucleation barrier. Therefore, the switching plasticity can be tuned by the perpendicular magnetic anisotropy of the multilayers and the in-plane magnetic field. Moreover, we used the switching plasticity of Co/Gd multilayers for demonstrating spike timing-dependent plasticity and sigmoid-like activation behavior. This work gives useful guidance to design multilevel spintronic devices which could be applied in high-performance neuromorphic computing.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Thermal oxidation and hydrogen annealing were applied on a 100 μm thick Al-doped p-type 4H-SiC epitaxial wafer to modulate the minority carrier lifetime, which was investigated by microwave photoconductive decay (μ-PCD). The minority carrier lifetime decreased after each thermal oxidation. On the contrary, with the hydrogen annealing time increasing to 3 hours, the minority carrier lifetime increased from 1.1 μs (as-grown) to 3.14 μs and then saturated after the annealing time reached 4 hours. The increase of surface roughness from 0.236 nm to 0.316 nm may also be one of the reasons for limiting the further improvement of minority carrier lifetimes. Moreover, the whole wafer mappings of minority carrier lifetimes before and after hydrogen annealing were measured and discussed. The average minority carrier lifetime was up to 1.94 μs and non-uniformity of carrier lifetime reached 38 % after 4-hours hydrogen annealing. The increasing minority carrier lifetimes could be attributed to the double mechanisms of excess carbon atoms diffusion caused by selective etching of Si atoms and passivation of deep-level defects by hydrogen atoms.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigated the band structure and Goos-Hänchen-Like shift in ferromagnetic mass graphene junction modulated by the circularly polarized light. It is found that both spin and valley-related energy gaps can be opened by employing the circularly polarized light and exchange fields in mass graphene. The valley-polarized Goos-Hänchen-Like shift can be identified in the presence of the circularly polarized light, and the spin-polarized Goos-Hänchen-Like shift can be realized with the introduction of an exchange field in mass graphene. Furthermore, the spin and valley polarization-related Goos-Hänchen-Like shift can be achieved with the combination of the circularly polarized light and exchange field in mass graphene. We hope that our work will be more conducive for future applications in graphene polarization transport devices.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Quantum anomalous Hall effect (QAHE) is an innovative topological spintronic phenomenon with dissipationless chiral edge states and attracts rapidly increasing attention. However, it has only been observed in few materials in experiments. Here, according to first-principles calculations, we report that the MXene MoYN<jats:sub>2</jats:sub>CSCl shows a topologically nontrivial band gap of 37.3 meV, possessing QAHE with a Chern number of <jats:italic>C</jats:italic> = 1, which is induced by band inversion between <jats:italic>d</jats:italic> <jats:sub> <jats:italic>xz</jats:italic> </jats:sub> and <jats:italic>d</jats:italic> <jats:sub> <jats:italic>yz</jats:italic> </jats:sub> orbitals. Also, the topological phase transition for MoYN<jats:sub>2</jats:sub>CSCl can be realized via strain or by turning the magnetization direction. Remarkably, MoYN<jats:sub>2</jats:sub>CSCl shows the nodal-line semimetal state dependent on the electron correlation <jats:italic>U</jats:italic>. Our findings add an experimentally accessible and tunable member to QAHE family, which stands a chance of enriching the applications in spintronics.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system return to its initial state after a single period is given by the means of the Landau-Zener-Stuckelberg-Majorana destructive interference. The nonadiabatic geometric phase ¨ accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In the past years, great progresses have been made on quantum computation and quantum simulation. The research with increasing number of qubits in the quantum processors are expected to be one of the main motivations in the next years, while noises in manipulation of quantum states may still be inevitable even the precision will improve. For research in this direction, it is necessary to review the available results about noisy multiqubit quantum computation and quantum simulation. The review focuses on multiqubit state generations, quantum computational advantage, simulating physics of quantum many-body systems. Perspectives of near term noisy intermediate-quantum processors will be discussed.</jats:p>