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Vanadium dioxide (VO2) has been one of the most significant functional materials for its prominent property change during phase transition. Here the modulation in crystallinity and morphology of VO2 thin film is achieved by femtosecond laser direct writing. Both the local crystallization from an amorphous phase and self-organized periodical structures are generated due to the well-controlled femtosecond laser energy deposition and controlled accumulation. The dynamic evolution of either the volumetric or surface nano-/micro-structure depends strongly on the femtosecond laser conditions, revealed by changes of the Raman bands and reflectance spectra at visible wavelengths. Based on the distinguishable color display performance of differently processed regions, a four-color-level image has been drawn on a VO2 thin film. This work proposes an elaborate "annealing by light" and optical property modulation method for the VO2, paving the way to producing complex integrated multi-functional devices for color display and data storage. [ABSTRACT FROM AUTHOR]

Perpendicular magnetic anisotropy (PMA) is one of the most significant technologies to be used in next generation spintronic devices due to its potential for promoting thermal stability and device miniaturization. It is an important issue to find an efficient way to modulate its property in the process of PMA application. In this work, we report the phase-transition controlled magnetic anisotropy modulation in the VO2/(Co/Pt)2 heterostructure, where VO2 is introduced into the system to apply an interfacial strain by its metal-insulator transition. A large reversible modulation of PMA reaching 3 × 105 erg/cm3 is observed during this process. The calculated energy density variation of interfacial anisotropy reaches 0.85 erg/cm2, which shows a significant advantage over traditional modulation strategies. Further experimental results including magnetization change versus temperature, strain buffered modulation, and pre-strained sample comparison prove that the interfacial coupling between VO2 and PMA layers plays a crucial role in this modulation. This work, demonstrating great potential for phase-transition materials in efficient magnetic anisotropy modulation, would benefit the exploration of low-power consumption devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solid-state synaptic transistor using SrFeO 2.5 channel was designed and fabricated. • An excellent symmetric behavior with an asymmetric ratio of only 0.19 is achieved. • A high level of MNIST pattern recognition accuracy (97.3%) was obtained. In the past few years, synaptic device has become a hot topic in material science because of the urgent demand of neuromorphic computing. Ionic liquids gated three-terminal synaptic transistors have drawn extensive attention due to their outstanding energy efficiency, linearity, and symmetry. However, utilization of liquid electrolyte is not appropriate for the requirement of the practical application. Herein, a novel three-terminal synaptic transistor is designed and constructed using a solid-state electrolyte gate and a brownmillerite SrFeO 2.5 thin film channel. Topotactic phase transformation can be induced between insulative brownmillerite SrFeO 2.5 and conductive perovskite SrFeO 3−δ. Nonvolatile conductance switching of the SrFeO x film can be realized by inserting and extracting of oxygen ions with electrolyte gating. The essential synaptic learning functions including excitatory postsynaptic current, and short-term/long-term plasticity, are successfully mimicked in the three-terminal synaptic transistor. This synapse device achieves a large scale adjusted range and multistable plasticity, demonstrating a new way to achieve key component of upcoming neuromorphic circuitry. [ABSTRACT FROM AUTHOR]