We have fabricated thin films of a van der Waals (vdW) ferromagnetic metal Fe5GeTe2 and characterized them by measuring the anomalous Hall effect. While the bulk Fe5GeTe2 does not exhibit a perpendicular magnetic anisotropy (PMA) unlike Fe3GeTe2, PMA emerges in the thin film devices. Furthermore, the PMA is enhanced with decreasing the thickness of Fe5GeTe2. In particular, a thin film (5 unit-cell layer) device fabricated with Fe5GeTe2 quenched at 1050 K has two times larger coercive field than that prepared without quenching. Such a PMA should be useful for future vdW spintronic devices.

We have performed magnetoresistance (MR) measurements on van der Waals ferromagnetic devices using quenched- (Q-) and nonquenched- (NQ-) Fe5GeTe2 crystals. A clear butterfly-shaped hysteresis has been observed for thin-film (less than 6 unit-cell layer) Q- and NQ-Fe5GeTe2 devices, but not for thicker film ones. The switching field of the butterfly-shaped MR is consistent with the coercive filed obtained from the Hall measurements. The MR ratio of the butterfly peak reaches about 10% at maximum, which is much larger than that observed with conventional magnetic materials. Such a large MR ratio would be related to magnetic fluctuations due to the complicated magnetic structure in this material.

Recovery of the organics in industrial wastewaters/liquid wastes as polyhydroxyalkanoate (PHA) and/or glycogen (GLG) in waste activated sludge is a useful strategy to not only improve the resource value of waste activated sludge but also reduce the energy and cost of waste disposal and wastewater treatment. This study aimed to evaluate the potential of activated sludge to accumulate PHA and GLG using complex substrates (actual and simulated industrial wastewaters/liquid wastes) in addition to various simple organic substrates (organic acids, saccharides, and glycerol). The 24 h PHA and GLG accumulation experiments resulted in the accumulation of up to 25.5%, 6.0% and 14.1% of polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and GLG, respectively, from simple substrates, and up to 9.8%, 0.1% and 14.6%, respectively, from complex substrates. The results indicated that activated sludge can accumulate PHA and GLG even from complex wastewater substrates, although the accumulated PHA and GLG levels were not sufficiently high. The results also indicated that the PHA and GLG accumulation abilities of activated sludge from complex substrates can be drastically enhanced by a short-term acclimation to the corresponding substrate. This study will present the practical implications for value-added resource production through the combined use of waste activated sludge and industrial wastewaters.

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