Tuning interlayer exchange coupling of co-doped TiO2/VO2 multilayers via metal-insulator transition

Photonic bandgap engineering in (VO2)n/(WSe2)nphotonic superlattice for versatile near- and mid-infrared phase transition applications

The application of the photonic superlattice in advanced photonics has become a demanding field, especially for two-dimensional and strongly correlated oxides. Because it experiences an abrupt metal-insulator transition near ambient temperature, where the electrical resistivity varies by orders of magnitude, vanadium oxide (VO₂) shows potential as a building block for infrared switching and sensing devices. We reported a first principle study of superlattice structures of VO₂as a strongly correlated phase transition material and tungsten diselenide (WSe₂) as a two-dimensional transition metal dichalcogenide layer. Based on first-principles calculations, we exploit the effect of semiconductor monoclinic and metallic tetragonal state of VO₂with WSe₂in a photonic superlattices structure through the near and mid-infrared (NIR-MIR) thermochromic phase transition regions. By increasing the thickness of the VO₂layer, the photonic bandgap (PhB) gets red-shifted. We observed linear dependence of the PhB width on the VO₂thickness. For the monoclinic case of VO₂, the number of the forbidden bands increase with the number of layers of WSe₂. New forbidden gaps are preferred to appear at a slight angle of incidence, and the wider one can predominate at larger angles. We presented an efficient way to control the flow of the NIR-MIR in both summer and winter environments for phase transition and photonic thermochromic applications. This study's findings may help understand vanadium oxide's role in tunable photonic superlattice for infrared switchable devices and optical filters.

Optically Tunable Magnetoresistance Effect: From Mechanism to Novel Device Application

The magnetoresistance effect in sandwiched structure describes the appreciable magnetoresistance effect of a device with a stacking of two ferromagnetic layers separated by a non-magnetic layer (i.e., a sandwiched structure). The development of this effect has led to the revolution of memory applications during the past decades. In this review, we revisited the magnetoresistance effect and the interlayer exchange coupling (IEC) effect in magnetic sandwiched structures with a spacer layer of non-magnetic metal, semiconductor or organic thin film. We then discussed the optical modulation of this effect via different methods. Finally, we discuss various applications of these effects and present a perspective to realize ultralow-power, high-speed data writing and inter-chip connection based on this tunable magnetoresistance effect.