Recently, the giant magneto impedance (GMI) effect has been studied extensively because of its potential applications in sensor elements. The focus of this thesis work is to explore different compositions and processing conditions for CoSiB and NiFe thin films to obtain the soft magnetic properties and to evaluate their potential use in GMI sensor applications. Prior to this study, an MH Looper was constructed, which was extremely important and provided the basic magnetic characterization of the many ferromagnetic thin films deposited during this work. The CoSiB films were co-sputter deposited in an ultra high vacuum chamber. Films with different relative compositions of Co, Si and B were deposited by varying respective target powers. Different substrate bias conditions were also studied. Also, NiFe films were studied by varying relative composition by variation of target powers and also by variation deposition pressure. The effect of annealing was also studied. The magnetic and electrical characterization of these films was done using the MH Looper, Quad-pro four-point probe resistivity measurement, and Low Frequency Impedance analyzer HP4192A. Finally, CoSiB films with soft magnetic properties were obtained with optimized set of deposition parameters. A sample for GMI measurement was prepared, consisting of a multilayer thin film structure: CoSiB 200nm/ Cu 400nm / CoSiB 200nm. A serpentine pattern was generated on this film by photolithography technique. After obtaining the pattern, GMI studies were performed using LF impedance analyzer. This instrument was capable of providing the drive frequency in the range of 5Hz to 13MHz, but the impedance mis-match of the test fixture limited useful measurements to 9MHz. The highest GMI ratio observed was 6.2% at a 21 Oe longitudinal magnetic bias field at an 8MHz drive frequency. Transverse permeability measurements were performed by the use of two magnetic field axes of the MH Looper. The permeability behavior of the device reflects the impedance behavior with the external field. Permeability measurements were also performed on NiFe GMI Device with NiFe 600nm/ Cu 1200nm / NiFe 600nm sandwich structure. This sample was not successfully patterned and hence the impedance measurements could not be performed. Correlation of the magnetic properties of the structures was studied with the impedance responses.

Motivated by previous relevant research on phononics including both active and passive phononics, the interest of faster turnability and more functions of the active phononics of further study led to this proposing research topic: magnetic field tunable active functional phononics. The first design of magnetic field tunable reciprocal--non-reciprocal transmission acoustic device was established, material was characterized, and numerical simulation has been performed. The simulation results show clear T-symmetric breaking non-reciprocity due to energy level splitting effect with Doppler effect – an acoustic Zeeman effect. Inspired by this preliminary work, further experiments were planned to demonstrate this effective Zeeman effect in phononics and effectively charged phonons in water based ferro-fluid. The objectives of this work as the next series of tasks were to illustrate acoustic Zeeman effect and acoustic Landau levels in various strength of magnetic field to investigate a design non-reciprocal sound device with magnetic field switching, which could be controlled on the amount of non-reciprocity with the strength of magnetic field. Once this new field first discovered by the proposed study tasks, more active tunable magnetic field phononics devices could be designed and exemplified in terms of both simulations and experiments. Faster and more controllable active phononic devices could be designed and made based on this study. The experimental maximum non-reciprocity was measured as 22 dB difference and the amount of the non-reciprocity can be further controlled by adjusting the strength of the external magnetic field. The remote pumping system in the device worked as expected and did not introduce any impact of the cavity properties.

This thesis focuses on investigating the possible x-ray illumination effects on the magnetic domain memory (MDM) in magnetic [Co/Pd]IrMn multilayers. In this material, MDM is induced via exchange couplings between the ferromagnetic Co/Pd layer and the antiferromagnetic IrMn layer. To carry out this investigation, we have used magneto-transport and x-ray resonant magnetic scattering. The use of magneto-transport in-situ at synchrotron x-ray scattering facility has allowed us to follow the gradual effect of x-ray illumination on the amount of exchange bias, initially present after field cooling the material. With our in-situ measurements we have been able to see that x-ray illumination does have an effect on the strength of exchange couplings in our material. To support this observation, we have also carried out complementary measurements at home in a cryomagnet, at various temperatures between 300K and 25K, and in a variety of configurations.

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Liquid metals (LMs) are compelling candidates for use as plasma facing components (PFCs) in fusion devices to mitigate heat loading, limit damage due to erosion, and possibly breed tritium. When used as electrodes, such as in z-pinch devices, PFCs are subject to large current and magnetic flux densities resulting in large Lorentz forces. Furthermore, if the PFCs are LM, the forces excite wave behavior that has not previously been investigated. The work presented here first characterizes the response of LMs to current pulses which peak between 50 and 200 kA and generate magnetic pressures between 0.5 and 5 MPa. High-speed videography records the liquid metal free surface during and after the current pulse and captures a fast moving, annular jet of LM emerging from the main body. The vertical velocities of the jet range from 0.6 to 5.3 m/s which is consistent with hydrodynamic predictions. Ejection of small droplets is observed from the LM immediately after the current pulse, preceding the LM jet, with velocities ranging from −3.1 to 18.9 m/s in the vertical direction and −14.3 to 6.3 m/s in the radial. A statistical model is developed to predict the likelihood of certain LM PFC material contaminating a core plasma and the severity in such an event. Lastly, effectiveness of bulk wave movement mitigation is investigated with two solid barrier designs, a cylindrical and conical baffle. These designs were fabricated after an iterative design process with assistance from hydrodynamic simulations. A cylindrical baffle design is shown to be preferable for integration into future fusion devices for the reduced likelihood of interference with plasma column formation. / Doctor of Philosophy / Liquid metals are considered for use as a coating on the interior surfaces in nuclear fusion reactors because they can remove heat, reduce damage, and generate additional fuel for the reactor. There has been very little research on what happens to the liquid metal when large amounts of electric current pass through it, as would be necessary in some designs. The work presented here first shows the liquid responds to large amounts of electric current with a fast moving, ring-shaped jet that correlates to the specific amount of current used. A theoretical relationship is used to relate the jet to hydrodynamic scenarios with solid bodies entering liquids. Small droplets are also observed sprayed from the LM earlier in time and the likelihood and severity of liquid metal contaminating the fusion core is analyzed. Finally, solid barriers are used to slow down the jet and minimize the mass it contains. To reduce the likelihood that the jet interferes with the fusion core, certain characteristics of barriers are identified as being preferable for use in plasma devices.

We have investigated the Faraday effect of bismuth-doped rare-earth iron-garnets with varying doping levels of gallium from z = 1.0 to 1.35. We used lutetium to control the film's in-plane magnetic properties and found that gallium doping levels above the compensation point caused a loss of anisotropy control, a canted out-of-plane magnetization in the film, and an extremely weak but linear coercivity above 10 micro-Tesla fields. Using these results we focused on in-plane films to create 8 layer stacks of 500 um thick films to achieve a minimum detectable field of 50 pT at 1 kHz. Unlike previous Magneto-Optic (MO) studies that typically used thin films of approximately 1um thickness, we used approximately 400um thick films to allow experimentation with the final, robust, ideal form the MO sensor would take. We measured what most other MO studies with garnets neglected: the magnetic anisotropy axis or structure within the film. Knowledge of this structure is essential in improving the sensitivity of a stacked MO probe. Studying thick films proved to be key to understanding the magnetic anisotropy and domain properties that can degrade or enhance the sensitivity of the Faraday rotation in bismuth doped rare-earth iron-garnets to an applied magnetic field and to pointing the direction of future research to develop the conditions for rugged magnetometer sensors. / Physics

A series of measurements aimed at comparing the magneto-elastic response and non-Joulian properties (magneto-volume) of single crystals of the iron-aluminum alloys Fe_81.8 Al_18.2 with different thermal treatments were per formed; the results of which confirmed net volume expansion in all field orientations. The magnitude of this expansion varied largely across various magnetic field alignments, with a greater than four times larger expansion for fields parallel to the [010] crystal axis than the [100] axis. The magnitude and direction of the change in volumetric expansion from quenched crystals to slow cooled crystals also depended heavily on the orientation of the magnetic field, with reduced magneto-volume responses ranging from ~2.4 to 0.5 times smaller for fields parallel to the [100] and [110] crystal axes respectively. These results present evidence of the non-Joulian effect and places crystals of the iron aluminum alloy Fe_81.8 Al_18.2 within the realm of functional non-Joulian magnets. / Mechanical Engineering