Investigations Of Magnetic/Electric Field Control Of Magnetization Of Ferromagnetic And Multiferroics

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The shortcomings of contemporary complementary metal oxide semiconductor (CMOS) technologies include increased power consumption, scalability, volatility, and device variability. New materials and novel devices are being investigated in this regard. Spintronic devices, which are normally based on magnetic materials, store and process data based on the modes of electron spins, rather than the presence or absence of charges as in the CMOS, are one possible approach. Numerous potential advantages of spintronic devices include its quick operational speed, low power requirement, and non-volatility. Two ferromagnetic materials suitable for creating spintronic devices are investigated in his dissertation study. Material properties, techniques for regulating the magnetization of materials, with both magnetic and electrical fields, and the development of devices useful for use in frequency modulations are all respectively detailed.The first section of this dissertation studies the magnetically-induced transparence (MIT) effect in Y3Fe5O12 (YIG)/Permalloy (Py) coupled bilayers. The measurement is achieved via a heterodyne detection of the coupled magnetization dynamics using a single wavelength that probes the magneto-optical Kerr and Faraday effects of Py and YIG, respectively. Clear features of the MIT effect are evident from the deeply modulated ferromagnetic resonance of Py due to the perpendicular-standing-spin-wave of YIG. We develop a phenomenological model that nicely represents the experimental results including the induced amplitude and phase evolution caused by the magnon-magnon coupling. This work offers a new route towards studying phase-resolved spin dynamics and hybrid magnonic systems. The second part of this dissertation discusses the research on the hexaferrite material, Zn2Y, and the prospect of controlling its magnetic characteristics by applying a dc voltage, which is akin to a bias electric field. The detection and investigation of the magnetoelectric (ME) effect for in-plane currents orthogonal to the hexagonal axis in single crystal and thin films of Zn2Y grown via liquid phase epitaxy. By applying a dc voltage, tuning of ferromagnetic resonance (FMR) was achieved in the hexaferrites. In addition to the frequency shift caused by the electrical tuning, magnetic properties of the material as a function of the input tuning power was also studied.



Engineering, Ferrites, Magnetism, Spintronics