Catálogo de publicaciones - revistas

<jats:p>We successfully overcome the problem of cross-talk in multiplexed metasurface design and realize the multiplexed metasurface with five printing images in both theoretical and experimental aspects, by employing the coherent pixel design considering coherent superposition of all the sub-elements. Compared with most previous studies where the integrated printing images were usually no more than three, our study shows obvious improvement. More importantly, in our approach all the sub-elements, which were crystalline silicon nanobricks with the size of 320 × 80 × 230 nm<jats:sup>3</jats:sup>, were arranged in a square space of 1.45 × 1.45 <jats:italic>μ</jats:italic>m<jats:sup>2</jats:sup> following the closest packing way, enabling our multiplexed metasurface to have a potential of effective physical information capacity of printing image reaching the optical diffraction limit. Our study not only enlarges the information capacity of metasurfaces by expanding the integrated number of printing image in one metasurface, but also can promote metasurface applications in various fields such as information storage and encoding.</jats:p>

<jats:p>A spintronics neuron device based on voltage-induced strain is proposed. The stochastic switching behavior, which can mimic the firing behavior of neurons, is obtained by using two voltage signals to control the in-plane magnetization of a free layer of magneto-tunneling junction. One voltage signal is used as the input, and the other voltage signal can be used to tune the activation function (Sigmoid-like) of spin neurons. Therefore, this voltage-driven tunable spin neuron does not necessarily use energy-inefficient Oersted fields and spin-polarized current. Moreover, a voltage-control reading operation is presented, which can achieve the transition of activation function from Sigmoid-like to ReLU-like. A three-layer artificial neural network based on the voltage-driven spin neurons is constructed to recognize the handwritten digits from the MNIST dataset. For the MNIST handwritten dataset, the design achieves 97.75% recognition accuracy. The present results indicate that the voltage-driven adaptive spintronic neuron has the potential to realize energy-efficient well-adapted neuromorphic computing.</jats:p>

<jats:p>Optical true delay lines (OTDLs) of low propagation losses, small footprints and high tuning speeds and efficiencies are of critical importance for various photonic applications. Here, we report fabrication of electro-optically switchable OTDLs on lithium niobate on insulator using photolithography assisted chemo-mechanical etching. Our device consists of several low-loss optical waveguides of different lengths which are consecutively connected by electro-optical switches to generate different amounts of time delay. The fabricated OTLDs show an ultra-low propagation loss of ∼ 0.03 dB/cm for waveguide lengths well above 100 cm.</jats:p>

<jats:p>The figure of merit <jats:italic>ZT</jats:italic> is the direct embodiment of thermoelectric performance for a given material. However, as an indicator of performance improvement, the only <jats:italic>ZT</jats:italic> value is not good enough to identify its outstanding inherent properties, which are highly sought in thermoelectric community. Here, we utilize one powerful parameter to reveal the outstanding properties of a given material. The weighted mobility is used to estimate the carrier transports of p-type SnS crystals, including the differences in doping level, carrier scattering and electronic band structure. We analyze the difference in carrier scattering mechanism for different crystal forms with the same doping level, then evaluate and confirm the temperature-dependent evolution of electronic band structures in SnS. Finally, we calculate the quality factor <jats:italic>B</jats:italic> based on the weighted mobility, and establish the relationship between <jats:italic>ZT</jats:italic> and <jats:italic>B</jats:italic> to further predict the potential performance in p-type SnS crystals with low cost and earth abundance, which can be realized through taking advantage of the inherent material property, thus improving <jats:italic>B</jats:italic> factor to achieve optimal thermoelectric level.</jats:p>

<jats:p>Layered material indium selenide (In<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Se<jats:sub> <jats:italic>y</jats:italic> </jats:sub>) is a promising candidate for building next-generation electronic and photonic devices. We report a zirconium aided MBE growth of this van der Waals material. When co-depositing zirconium and selenium onto an indium phosphide substrate with a substrate temperature of 400°C at a constant zirconium flux rate of 0.01 ML/min, the polymorphic In<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Se<jats:sub> <jats:italic>y</jats:italic> </jats:sub> layer emerges on top of the insulating ZrSe<jats:sub>2</jats:sub> layer. Different archetypes, such as InSe, <jats:italic>α</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> and <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>, are found in the In<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Se<jats:sub> <jats:italic>y</jats:italic> </jats:sub> layers. A negative magnetoresistance of 40% at 2K under 9T magnetic field is observed. Such an In<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Se<jats:sub> <jats:italic>y</jats:italic> </jats:sub>/ZrSe<jats:sub>2</jats:sub> heterostructure with good lattice-matching may serve as a candidate for device applications.</jats:p>

<jats:p>We present a theory of both the itinerant carrier-mediated RKKY interaction and the virtual excitations-mediated Bloembergen–Rowland (BR) interaction between magnetic moments in graphene induced by proximity effect with a ferromagnetic film. It is shown that the RKKY/BR interaction consists of the Heisenberg, Ising, and Dzyaloshinskii–Moriya (DM) terms. In the case of the nearest distance, we estimate the DM term from the RKKY/BR interaction is about 0.13 meV for the graphene/Co interface, which is consistent with the experimental result of DM interaction 0.16±0.05 meV. Our calculations indicate that the intralayer RKKY/BR interaction may be a possible physical origin of the DM interaction in the graphene-ferromagnet interface. This work provides a new perspective to comprehend the DM interaction in graphene/ferromagnet systems.</jats:p>

<jats:p>There is a considerable amount of work that shows the biomagnetism of organic components without ferromagnetic components at the molecular level, but it is of great challenge to cover the giant gap of biomagnetism between their experimental and theoretical results. Here we show that the diamagnetism of aromatic peptides is greatly enhanced for about 11 times by self-assembling, reaching two orders of magnitude higher than the mass susceptibility of pure water. The self-assembly of aromatic rings in the peptide molecules plays the key role in such a strong diamagnetism.</jats:p>