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High Frequency Multiferroic Devices

  • Author(s): Hu, Jinzhao
  • Advisor(s): Carman, Gregory P
  • Sepulveda, Abdon E
  • et al.
Abstract

This dissertation focuses on high frequency multiferroic devices from both theoretical and experimental aspects. Some potential applications for high frequency multiferroic: antennas, logic and memory, will be presented in this dissertation. The introduction section provides a fundamental explanation on the multiferroic devices as well as the modeling methods for strain-mediated multiferroic systems. Former researches indicate that the composites of piezoelectric substrate and the magnetoelastic material show great potential on reducing both the devices’ size as well as energy consumption.

Part I of the dissertation shows multiferroics for antenna applications. Conventionally, antennas such as dipoles and loops rely on an electromagnetic (EM) wave resonance. Therefore, the sizes of such antennas are within the same order of free space wavelength. Multiferroic antenna can transfer the EM wave into an acoustic wave, which has much smaller wavelength compared with the wavelength of the EM wave under the same frequency. In this way, multiferroic antennas show a promising path for reducing the antenna system’s size, weight and volume. Also, three multiferroic antennas: shear wave antenna, lamb wave antenna as well as tunable frequency broadband antenna are introduced in this section. The shear wave antenna and lamb wave antenna are studied experimentally, and the tunable frequency broadband antenna is studied theoretically. All of them show great potential on reducing the antenna’s size.

Part II of this dissertation indicates other applications of multiferroic devices: logic and memory. For the logic aspects, a numerical simulation is performed on in-plane mode Bennett clocking systems. For memory aspects, a new concept for breaking the switch symmetry the high frequency control of the magnetization in nanodisk. In this part, a fully coupled finite element model is used to simulate the switch process of the magnetization in the nanodisks. This voltage-controlled process has potential be used in magnetic memory devices with very low energy dissipations.

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