Intrinsic magnetic topological insulator (TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel topological quantum effects but remains elusive experimentally so far. Here, we report the experimental realization of high-quality thin films of an intrinsic magnetic TI-MnBi2Te4-by alternate growth of a Bi2Te3 quintuple-layer and a MnTe

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This paper describes a strategy to impart brittle conductive patterns composed of silver nanoparticles with high stretchability and structure‐dependent electrical characteristics. Silver nanoinks are printed on an elastomeric polyurethane acrylate substrate in the form of planar serpentine structures that can effectively mitigate strain concentration. The relative changes in resistance (∆R/R 0) and stretchability are found to strongly depend on the serpentine radius (r) that determines the strain relieving efficiency. Features with small radius of curvature show colossal ∆R/R 0 and hold great promise as ultrasensitive stretchable strain gauges. A record high gauge factor of 107 is achieved at 12% strain with r = 200 µm. Devices with larger radius of curvature exhibit higher stretchability and much more stable conductance, thus can be used as stretchable conductors. The results demonstrate the versatile functionalities that can be acquired from conventional materials by judicious structural designs.

Recently, there has been tremendous research efforts on the development of energy harvesters that can scavenge energy from ubiquitous forms of mechanical energy. The most studied mechanisms are based on the use of piezoelectric and triboelectric effects. Polypropylene ferroelectret (PPFE) is introduced here as the active material in an efficient, flexible, and biocompatible ferroelectret nanogenerator (FENG) device. PPFE is charged polymers with empty voids and inorganic particles that create giant dipoles across the material's thickness. Upon applied pressure, the change in the dipole moments generate a change of the accumulated electric charge on each surface of the PPFE film, resulting in a potential difference between the two electrodes of the FENG. The mechanical-electrical energy conversion mechanism in PPFE films is described by finite element method (FEM). Further investigation of

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