Catálogo de publicaciones - revistas

<jats:p>We study the behavior of two-dimensional electron gas in the fractional quantum Hall (FQH) regime in the presence of disorder potential. The principal component analysis is applied to a set of disordered Laughlin ground state model wave function to enable us to distill the model wave function of the pure Laughlin state. With increasing the disorder strength, the ground state wave function is expected to deviate from the Laughlin state and eventually leave the FQH phase. We investigate the phase transition from the Laughlin state to a topologically trivial state by analyzing the overlap between the random sample wave functions and the distilled ground state wave function. It is proposed that the cross point of the principal component amplitude and its counterpart is the critical disorder strength, which marks the collapse of the FQH regime.</jats:p>

<jats:p>Breakdown of bulk-boundary correspondence in non-Hermitian (NH) topological systems with generalized inversion symmetries is a controversial issue. The non-Bloch topological invariants determine the existence of edge states, but fail to describe the number and distribution of defective edge states in non-Hermitian topological systems. The state-dependent topological invariants, instead of a global topological invariant, are developed to accurately characterize the bulk-boundary correspondence of the NH systems, which is very different from their Hermitian counterparts. At the same time, we obtain the accurate phase diagram of the one-dimensional non-Hermitian Su–Schrieffer–Heeger model with a generalized inversion symmetry from the state-dependent topological invariants. Therefore, these results will be helpful for understanding the exotic topological properties of various non-Hermitian systems.</jats:p>

<jats:p>We report the experimental investigation of the superconductor-metal quantum phase transition of the EuO/KTaO<jats:sub>3</jats:sub> interface. Around the transition, a divergence of the dynamical critical exponent is observed, which supports the quantum Griffiths singularity in the EuO/KTaO<jats:sub>3</jats:sub> interface. The quantum Griffiths singularity could be attributed to large rare superconducting regions and quenched disorders at the interface. Our results could pave the way for studying the exotic superconducting properties at the EuO/KTaO<jats:sub>3</jats:sub> interface.</jats:p>

<jats:p>We report a perpendicular magnetic tunnel junction (pMTJ) cell with a tunnel magnetoresistance (TMR) ratio of nearly 200% at room temperature based on CoFeB/Ta/CoFeB as the free layer (FL) and a synthetic antiferromagnetic (SAF) multilayer [Pt/Co]/Ru/[Pt/Co]/Ta/CoFeB as the reference layer (RL). The field-driven magnetization switching measurements show that the pMTJs exhibit an anomalous TMR hysteresis loop. The spin-polarized layer CoFeB of SAF-RL has a lower critical switching field than that of FL. The reason is related to the interlayer exchange coupling (IEC) through a moderately thick Ta spacer layer among SAF-RLs, which generates a moderate and negative bias magnetic field on CoFeB of RL. However, the IEC among RLs has a negligible influence on the current-driven magnetization switching of FL and its magnetization dynamics.</jats:p>

<jats:p>We report a distinctive way for designing lead-free films with high energy storage performance. By inserting different single perovskite cells into Bi<jats:sub>4</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>12</jats:sub>, <jats:italic>P</jats:italic>–<jats:italic>E</jats:italic> hysteresis loops present larger maximum polarization, higher breakdown strength and smaller slim-shaped area. We prepared 0.15Bi<jats:sub>7</jats:sub>Fe<jats:sub>3</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>21</jats:sub>-0.5Bi<jats:sub>4</jats:sub>Sr<jats:sub>3</jats:sub>Ti<jats:sub>6</jats:sub>O<jats:sub>21</jats:sub>-0.35Bi<jats:sub>4</jats:sub>Ba<jats:sub>3</jats:sub>Ti<jats:sub>6</jats:sub>O<jats:sub>21</jats:sub> solid solution ferroelectric films employing the sol-gel method, and obtained high energy storage density of 132.5 J/cm<jats:sup>3</jats:sup> and efficiency of 78.6% while maintaining large maximum polarization of 112.3 <jats:italic>μ</jats:italic>C/cm<jats:sup>2</jats:sup> and a high breakdown electric field of 3700 kV/cm. Moreover, the energy storage density and efficiency exhibit stability over the temperature range from 20 °C to 125 °C, and anti-fatigue stability maintains up to 10<jats:sup>8</jats:sup> cycles. The films with a simple preparation method and high energy storage performance are likely to become candidates for high-performance energy storage materials.</jats:p>

<jats:p>High-performance WSe<jats:sub>2</jats:sub> complementary transistors are demonstrated on an individual flake by ozone exposure, which relies on the charge transfer mechanism. This technology is readily feasible for modulating the conductivity type in WSe<jats:sub>2</jats:sub>, and the p–n junction presents a high on-off ratio of 10<jats:sup>4</jats:sup>. Based on robust p-type transistors and matched output current of n-type WSe<jats:sub>2</jats:sub> transistors, the complementary inverter achieves a high voltage gain of 19.9. Therefore, this strategy may provide an avenue for development of high-performance complementary electronics.</jats:p>

<jats:p>The DArk Matter Particle Explorer (DAMPE) is a satellite-borne detector for high-energy cosmic rays and <jats:italic>γ</jats:italic>-rays. To fully understand the detector performance and obtain reliable physical results, extensive simulations of the detector are necessary. The simulations are particularly important for the data analysis of cosmic ray nuclei, which relies closely on the hadronic and nuclear interactions of particles in the detector material. Widely adopted simulation softwares include the GEANT4 and FLUKA, both of which have been implemented for the DAMPE simulation tool. Here we describe the simulation tool of DAMPE and compare the results of proton shower properties in the calorimeter from the two simulation softwares. Such a comparison gives an estimate of the most significant uncertainties of our proton spectral analysis.</jats:p>

<jats:p>A quantum computer is not necessarily alone, e.g., thousands and millions of quantum computers are simultaneously working together for adiabatic quantum computers based on nuclear spins. Long-range interaction is inevitable between these nuclear spin qubits. Here we investigate the effect of long-range dipolar interaction between different adiabatic quantum computers. Our analytical and numerical results show that the dipolar interaction can enhance the final fidelity in adiabatic quantum computation for solving the factorization problem, when the overall interaction is negative. The enhancement will become more prominent if a single quantum computer encounters an extremely small energy gap which occurs more likely for larger-size systems.</jats:p>

<jats:p>Active metamaterials have shown huge advantages to control electromagnetic and acoustic waves. However, how to use active metamaterials to control thermal waves has not been explored, though thermal waves are significant in various fields. To address the problem, here we report an active scheme for thermal wave cloaks. The thermal waves are based on conduction and convection, which are dominated by the Fourier and Darcy laws, respectively. By calculating the propagation of thermal waves in a free space, we can derive the global temperature and pressure distributions. We then apply these calculation results to actively control the boundary temperature and pressure, and active thermal wave cloaks can be obtained. Compared with existing passive schemes to control thermal waves, the present active scheme is more flexible for switching on/off and changing geometries. This work provides active and controllable components to thermal wave cloaks, which can be further used to design more active thermal wave metamaterials.</jats:p>

<jats:p>We propose a model for three-terminal thermionic heat engines based on semiconductor heterostructures. According to electron transport theory, we drive the formulas for the charge current and energy current flowing from the electron reservoir and we then obtain the power output and efficiency in the linear and nonlinear regimes. Furthermore, we analyze the performance characteristic of the thermionic heat engine and get the maximum power output by optimizing the performance parameters. Finally, we optimize the thermodynamic performance of the thermionic heat engine by maximizing the product of the power output and efficiency.</jats:p>