Three novel organic dyes based on porphyrin derivatives were designed and synthesized for dye-sensitized solar cells, resulting in a maximum power conversion efficiency (eta) of 5.14% and a maximum IPCE value of 72% for a cell based on the dye.
We demonstrate a memory device with multifield switchable multilevel states at room temperature based on the integration of straintronics and spintronics in a La2/3Ba1/3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) (011) heterostructure. By precisely controlling the electric field applied on the PMN-PT substrate, multiple nonvolatile resistance states can be generated in La2/3Ba1/3MnO3 films, which can be ascribed to the strain-modulated metal-insulator transition and phase separation of Manganite. Furthermore, because of the strong coupling between spin and charge degrees of freedom, the resistance of the La2/3Ba1/3MnO3 film can be readily modulated by magnetic field over a broad temperature range. Therefore, by combining electroresistance and magnetoresistance effects, multilevel resistance states with excellent retention and endurance properties can be achieved at room temperature with the coactions of electric and magnetic fields. The incorporation of ferroelastic strain and magnetic and resistive properties in memory cells suggests a promising approach for multistate, high-density, and low-power consumption electronic memory devices.
Magnetoelectric materials which simultaneously exhibit electric polarization and magnetism have attracted more and more attention due to their novel physical properties and promising applications for next-generation devices. Exploring new materials with outstanding magnetoelectric performance, especially the manipulation of magnetization by electric field, is of great importance. Here, we demonstrate the cross-coupling between magnetic and electric orders in polycrystalline Co4Nb2O9, in which not only magnetic-field-induced electric polarization but also electric field control of magnetism is observed. These results reveal rich physical phenomenon and potential applications in this compound.
Determination of the structures of materials involving
more light
elements such as boron-rich compounds is challenging and technically
important in understanding their varied compositions and superior
functionalities. Here we resolve the long-standing uncertainties in
structure and composition about the highest boride (termed MoB4, Mo1–x
B3, or
MoB3) through the rapid formation of large-sized boron-rich
molybdenum boride under pressure. Using high-quality single-crystal
X-ray diffraction analysis and aberration-corrected scanning transmission
electron microscopy, we reveal that boron-rich molybdenum boride with
a composition of Mo0.757B3 exhibits P63/mmc symmetry with a partial
occupancy of 0.514 in 2b Mo sites (Mo1), and direct
observations reveal the short-range ordering of cation vacancies in
(010) crystal planes. Large anisotropic Young’s moduli and
Vickers hardness are seen for Mo0.757B3, which
may be attributed by its two-dimensional boron distributions. Mo0.757B3 is also found to be superconducting with
a transition temperature (T
c) of ∼2.4
K, which was confirmed by measurements of resistivity and magnetic
susceptibility. Theoretical calculations suggest that the partial
occupancy of Mo atoms plays a crucial role in the emergence of superconductivity.
Two-dimensional topological insulators show great promise for spintronic applications. Much attention has been placed on single atomic or molecular layers, such as bismuthene. The selections of such materials are, however, limited. To broaden the base of candidate materials with desirable properties for applications, we report herein an exploration of the physics of double layers of bismuthene and antimonene. The electronic structure of a film depends on the number of layers, and it can be modified by epitaxial strain, by changing the effective spin-orbit coupling strength, and by the manner in which the layers are geometrically stacked. First-principles calculations for the double layers reveal a number of phases, including topological insulators, topological semimetals, Dirac semimetals, trivial semimetals, and trivial insulators. Their phase boundaries and the stability of the phases are investigated. The results illustrate a rich pattern of phases that can be realized by tuning lattice strain and effective spin-orbit coupling.
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