Novel electrostatically tunable FeGaB/(Si)/PMN-PT multiferroic heterostructures for microwave application

Strong magnetoelectric (ME) coupling can be realized in multiferroic heterostructures, which have led to a variety of devices. However, it has been challenging in achieving strong ME coupling at microwave frequencies. Here, we report on novel FeGaB/Si/PMN-PT and FeGaB/PMN-PT microwave multiferroic heterostructures, which show strong ME coupling at both DC and microwave frequencies. A high microwave frequency tunability of Deltaf = 900 MHz or Deltaf/f = 58%, which is equivalent to a magnetic field tunable range of ~30 Oe, was demonstrated in the FeGaB/Si/PMN-PT heterostructures. By eliminating the Si substrate, which acts to impede the ME coupling, a much larger tunable magnetic field range of ~330 Oe was observed in the FeGaB/PMN-PT heterostructures. These multiferroic heterostructures with strong ME coupling provide great opportunities for electrostatically tunable ME microwave devices.