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The anomalous Nernst effect (ANE) has been under consideration for potential transverse thermoelectric applications. However, the utilized material systems are generally limited to chemically ordered crystals with notable features of nontrivial band topology and/or strong spin–orbit coupling, such as topological ferromagnets and antiferromagnets. In this study, we present the observation of a robust room-temperature ANE in a chemically disordered ferromagnet, specifically an A1-type FexPt100−x alloy. The observed anomalous Nernst thermopower Sxy (∼1.6 μV/K) remains stable over a wide range of thicknesses (6 ≤ t ≤ 100 nm) and compositions (46 ≤ x ≤ 67), which is in stark contrast to the common situation in topological ferromagnets. This behavior can be attributed to both the large anomalous Nernst conductivity αxy (∼1.3 A K−1 m−1), originating from Berry phase effects, as well as the significant Seebeck-driven anomalous Hall effect that modulates its action through mean-free-path and two-carrier models. [ABSTRACT FROM AUTHOR]

Low activator concentration in upconversion phosphors has been a hindrance in improving luminescence performance. Herein, we report an Er3+ doping concentration as high as 30 at. % in the CaLuAlO4 upconversion host. The CaLuAlO4:Er3+ phosphors were prepared by the traditional high-temperature solid-state method. Under the excitation of a 980 nm laser, the optimal concentration of Er3+ approaches 30% according to the total integrated intensity of red and green upconversion luminescence. This quenching concentration is one order of magnitude higher than that in the traditional Er3+ doped upconversion polycrystals. The results obtained from first-principles calculations suggest that there are no in-plane or chain rare-earth ions in the cell. This increases the difficulty of propagating excitation energy to quench centers and is advantageous for high doping concentration. Our work can spark people's interest in the research and application of highly doped upconversion phosphors. [ABSTRACT FROM AUTHOR]

A large rotating magnetocaloric effect (RMCE) was always observed in the materials with anisotropic magnetisms, for example, ferromagnetism vs antiferromagnetism or paramagnetism, at different crystallographic directions. In this work, anisotropic ferromagnetic susceptibility is utilized to implement low-field (≤2 T) large RMCE in the textured polycrystalline HoB2 alloy. The x-ray diffraction and scanning electron microstructure results reveal that the arc-melted HoB2 exhibits preferred grain orientation along the solidification direction. The measured rotating magnetic entropy changes (−ΔSR) and refrigeration capacity are 6.27 J/kg K and 73.7 J/kg, respectively, under the magnetic field change of 1 T. They are comparable with those of other materials contributed by anisotropic magnetisms. Our results suggest that the polycrystal HoB2 alloy is a promising material for practical application of magnetic refrigeration based on RMCE. [ABSTRACT FROM AUTHOR]

We present an optomechanical scheme for selective self-excitation of a particular mechanical mode of a micro-cantilever. Depending on the slope of interference, the oscillation of the laser illuminated micro-cantilever can be either damped or enhanced by the retarded bolometric backaction. Selective self-excitation of the first two modes is achieved by positioning the laser spot on a specific region along the lever. A theoretical simulation has been performed to provide guidance in the photothermal self-excitation of higher-order modes. This efficient self-excitation technique offers a simple control scheme in force microscopy imaging with higher-order mechanical mode of micro-cantilever. [ABSTRACT FROM AUTHOR]