Strain-induced high-temperature perovskite ferromagnetic insulator.

Ferromagnetic insulators are required for many new magnetic devices, such as dissipationless quantum-spintronic devices, magnetic tunneling junctions, etc. Ferromagnetic insulators with a high Curie temperature and a high-symmetry structure are critical integration with common single-crystalline oxide films or substrates. So far, the commonly used ferromagnetic insulators mostly possess low-symmetry structures associated with a poor growth quality and widespread properties.

Engineering the exchange bias and bias temperature by modulating the spin glassy state in single phase BiFeTiO.

Exchange anisotropy is normally observed at ferromagnetic (FM)/anti-ferromagnetic (AFM) interfaces and also usually at low temperatures. An effective way to find new single-phase materials with strong exchange bias (EB) and high operation temperatures is required for making them useful in practical applications of future spintronic devices. In this work, the exchange bias behaviors of single phase BiFeTiO (BFT) were found able to be manipulated by altering its spin glassy state, when the material was intentionally prepared in the nanobelt format.

Giant frequency tunability enabled by external magnetic and a gate electric fields in graphene devices.

Graphene possesses a unique Landau level system that is non-equidistantly spaced in energy, as thus a large amount of optical transitions may become possible. Here, by utilizing this unique feature, we propose a novel dual field method which combines both external magnetic field and gate electric field together to control the optical response of the graphene-based devices. The key principle of this method is to selectively allow different optical transitions in graphene among Landau levels via an electric gate tuning of the Fermi level.

Hybrid tandem solar cell enhanced by a metallic hole-array as the intermediate electrode.

A metallic hole-array structure was inserted into a tandem solar cell structure as an intermediate electrode, which allows a further fabrication of a novel and efficient hybrid organic-inorganic tandem solar cell. The inserted hole-array layer reflects the higher-energy photons back to the top cell, and transmits lower-energy photons to the bottom cell via the extraordinary optical transmission (EOT) effect. In this case light absorption in both top and bottom subcells can be simultaneously enhanced via both structural and material optimizations.

Nanoscale structural modulation and enhanced room-temperature multiferroic properties.

Availability of a single-phase multiferroic material functional at room temperature poses a big challenge, although it is very important to both fundamental physics and application development. Recently, layered Aurivillius oxide materials, one of the most promising candidates, have attracted considerable interest. In this work, we investigated the nanoscale structural evolution of the six-layer Bi7Fe(3-x)Co(x)Ti3O21 when substituting excessive Co.

Enhanced photon absorption and carrier generation in nanowire solar cells.

Overall performance of a thin film solar cell is determined by the efficiency of converting photons to electrons through light absorption, carrier generation, and carrier collection. Recently, photon management has emerged as a powerful tool to further boost this conversion efficiency. Here we propose a novel nanograting solar cell design that achieves enhanced broadband light absorption and carrier generation in conjunction with the reduced use of active and non-earth-abundant materials.