Tohoku University Technology: Polycrystalline Heusler alloy thin film: T20-2968

Polycrystalline Heusler alloy film exhibiting performance comparable to that for a single crystal, which can be formed on a flexible substrate

Co-based Heusler alloy such as Co2MnGa or Co2MnAl has attracted attention as candidate materials for high-sensitivity sensor and high-efficiency thermoelectric conversion element thanks to their large anomalous Nernst and Hall effects. In order to realize these excellent properties, it is thought that a single crystalline bulk material or a thin film grown on a single crystalline substrate is necessary. Thus, such single crystalline samples have been produced. Considering that those materials are applied to actual devices, it is necessary that a polycrystalline film, which does not use a single crystalline substrate, shows the property equivalent to those of single crystalline material. 　This invention is able to provide a “polycrystalline Heusler alloy thin film" that does not require a single crystalline substrate, while showing the properties of anomalous Hall angle (θAH~7.5%) and anomalous Nernst coefficient (SANE~5μV/K) comparable to a single crystalline thin film. It can promote the control of crystal orientation and the improvement of crystallinity by sandwiching the polycrystalline layer with an insulating AlN layer.

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