Layered magnetic/piezoelectric heterostructures have drawn a great amount of interest for their potential use in ultra-sensitive magnetoelectric (ME) sensors, ME antennas, voltage tunable inductors and magnetic tunable resonators, etc. It is critically important to achieve a high piezomagnetic coefficient, which determine the magnetoelectric coupling strength, and the performance of these ME devices. Recently we reported new FeGaB films with a strong piezomagnetic coefficient of 7ppm/Oe before magnetic annealing [1,2], which was increased to 12ppm/Oe after magnetic annealing . We also investigated the dependence of magnetostriction and piezomagnetic coefficient on different carbon content in FeGa and FeCo based thin films. By incorporating of metalloid element carbon into FeGa and FeCo alloys, the nanocrystalline phase was destabilized which was detrimental to high saturation magnetostriction. The coexistence of microstructure in both nanocrystalline phase and amorphous phase led to a dramatical enhancement in soft magnetic and microwave properties. With carbon content of 11% and 5% in FeGaC and FeCoC respectively [4,5], a giant piezomagnetic coefficient of 10 ppm/Oe has been achieved in both type of thin films before magnetic annealing, making them superior materials for applications in ME devices.
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