Science Daily July 4, 2023 Dielectric capacitors can become ideal, safe energy storage devices. However, they yield rather low energy densities compared with other energy storage devices such as batteries and supercapacitors. Researchers in Japan designed ultrahigh energy storage capacitors using two-dimensional (2D) high-κ dielectric perovskites (Ca2Nam–3NbmO3m+1; m = 3–6). Individual Ca2Nam–3NbmO3m+1 nanosheets exhibited an ultrahigh dielectric strength even in the monolayer form, which exceeded those of conventional dielectric materials. Multilayer stacked nanosheet capacitors exhibited ultrahigh energy densities, high efficiencies (>90%), excellent reliability (>107 cycles), and temperature stability (−50–300 °C); the maximum energy density was much higher than those of […]
Tag Archives: Insulators
Chip-scale Floquet topological insulators to enhance 5G wireless communications
Phys.org May 30, 2022 A team of researchers in the US (Columbia University, City University of New York, UT Austin, industry) introduced Floquet topological insulators for radio-waves with a unique design, based on the quasi-electrostatic propagation of radio signals in switched-capacitor networks. In their previous work they developed photonic topological insulators (PTI) chips that could be used to create full-duplex phased-array wireless technology, which combines two different 5G wireless capabilities: full-duplex and multi-antenna operation. PTIs do not allow the propagation of electromagnetic waves in their bulk, but they ensure efficient and robust wave propagation on their boundaries, however shaped. These […]
Quantum one-way street in topological insulator nanowires
Phys.org May 12, 2022 Recently quantum mechanical non-reciprocal transport effects that enable a highly controllable rectification were discovered. One such effect is magnetochiral anisotropy (MCA) in which the resistance of a material or a device depends on both the direction of the current flow and an applied magnetic field. However, the size of rectification possible due to MCA is usually extremely small because MCA relies on inversion symmetry breaking that leads to the manifestation of spin–orbit coupling, which is a relativistic effect. To overcome this limitation, an international team of researchers (Switzerland, Germany, Belgium) artificially broke the inversion symmetry via […]