Spintronic nanodevices have ultrafast nonlinear dynamic and recurrence behaviors on a nanosecond scale that promises to enable a high-performance spintronic reservoir computing (RC) system. Here, two physical RC systems based on one single magnetic skyrmion memristor (MSM) and 24 spin-torque nano-oscillators (STNOs) are numerically modeled to process image classification task and nonlinear dynamic system prediction, respectively. Based on the nonlinear responses of the MSM and STNO with current pulse stimulation, our results demonstrate that the MSM-based RC system exhibits excellent performance on image classification, while the STNO-based RC system does well in solving the complex unknown nonlinear dynamic problems, e.g., a second-order nonlinear dynamic system and NARMA10. Our result and analysis of the current-dependent nonlinear dynamic properties of the MSM and STNO provide the strategy to optimize the experimental parameters in building the better spintronic-based brainlike devices for machine learning based computing.

Potassium‐ (PIBs) and sodium‐ion batteries (SIBs) are emerging as promising alternatives to lithium‐ion batteries owing to the low cost and abundance of K and Na resources. However, the large radius of K+ and Na+ lead to sluggish kinetics and relatively large volume variations. Herein, a surface‐confined strategy is developed to restrain SnS2 in self‐generated hierarchically porous carbon networks with an in situ reduced graphene oxide (rGO) shell (SnS2@C@rGO). The as‐prepared SnS2@C@rGO electrode delivers high reversible capacity (721.9 mAh g−1 at 0.05 A g−1) and superior rate capability (397.4 mAh g−1 at 2.0 A g−1) as the anode material of SIB. Furthermore, a reversible capacity of 499.4 mAh g−1 (0.05 A g−1) and a cycling stability with 298.1 mAh g−1 after 500 cycles at a current density of 0.5 A g−1 were achieved in PIBs, surpassing most of the reported non‐carbonaceous anode materials. Additionally, the electrochemical reactions between SnS2 and K+ were investigated and elucidated.

Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La 2/3 Sr 1/3 MnO 3 (LSMO)/ BaTiO 3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacing with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin-lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin-lattice coupling.spin-lattice coupling | interfaces | magnetic/electric | structural transition | ultrathin films I nterface physics has emerged as one of the most popular methods to discover unique phenomena caused by broken symmetry (1-6). In transition metal oxide (TMO) interfaces, the different electronic, magnetic, lattice, and orbital properties of two adjoined materials lead to fascinating properties that are often radically different from those of the two component bulk materials (7-10). It would seem that we are on the verge of being able to design (11) or engineer (12) the properties of interfaces.Although the behavior of individual interfaces has been widely investigated, how two or more interfaces behave within superlattices (SLs) remains an interesting and open topic (13,14). As shown in Fig. 1A, when two interfaces are geometrically close enough, they can drastically alter the properties of the material in between because of proximity effects. Unlike layered compounds, such as Fe-based superconductors and cuprates, which have pronounced 2D properties, most perovskites with the chemical formula ABO 3 exhibit drastic decreases in their functionalities under reduced dimensionality (i.e., ultrathin materials). This property has hindered the exploration and development of active low-dimensional materials (15, 16). Therefore, exploring ultrathin materials confined by two interfaces is a rational approach to see whether interfacial effects can be exploited to achieve desired functionalities.In this work, we present an example of using the structural phase change induced by two adjacent interfaces as a route to design ultrathin TMOs. We choose two materials with distinct properties: BaTiO 3 (BTO), which in its bulk form, is polar ferroelectric, and La 2/3 Sr 1/3 MnO 3 (LSMO), which in its bulk form, is nonpolar/tilt ferromagnetic....

No abstract