Electromagnets use current to change magnetization which is impractical on the small-scale and generates high electrical power consumption. Applying a voltage rather than current such as by using magneto-ionics allows for the alteration of a material composed of small particles. This project aims at replicating the results in the micron-scale on the nanoscale. SmCo5 nanoparticles are hydrogenated in an electrolytic cell which uses samarium cobalt as the working electrode, platinum as the counter, and silver-silver chloride as the reference electrode with an electrolyte of KOH. The chemical reaction that takes place is induced by the application of 1 V.This method has been successfully used with SmCo5 to control the magnetization of micron-scale particles but with a 20-hour duration needed to achieve results [Ye, X., Singh, H.K., Zhang, H. et al. Giant voltage-induced modification of magnetism in micron-scale ferromagnetic metals by hydrogen charging. Nat Commun 11, 4849 (2020)]. Using smaller particle sizes that have a higher surface-area-to-volume ratio will expedite the process. Cyclic voltammetry is used to measure the current generated by the reaction to make sure that enough hydrogen is being produced to alter the magnetization of the material without producing an excess of hydrogen which can degrade the material, XRD is used to measure how much the expansion of the material’s crystal lattice, SQUID magnetometry is used to examine magnetism changes. Controlling a substance’s magnetism efficiently and at room temperature will be useful in applications such as small biomedical devices, data storage, and if refined, cell sorting.

Current cell sorting methods are relying on cell surface expression. However, emerging cell therapies can benefit from selecting individual cells based on their complex behaviors or time-dependent functions, which are not directly correlated to cell surface protein expression. Single-domain multiferroic array-addressable Terfenol-D (SMArT) micromagnets have shown their ability to capture magnetic beads as well as magnetically tagged cells with consistent precision. Terfenol-D is the material chosen, as it has the highest magnetostrictive strain of any soft magnetoelastic material. The direction and intensity of magnetization can be controlled with voltage-induced strain by accompanying magnetostrictive materials with ferroelectric material. Through voltage-induced strain, the magnetic state of these micromagnets can be switched, resulting in a multiferroic approach to trap, incubate, and release magnetically-labeled single cells. Therefore, multiferroics present an opportunity to automate single-cell selection based on functional and time-dependent properties.

Next generation magnetic memory devices based on spin orbit torque effects promise to revolutionize the industry of computing but are currently limited due to high write currents and inefficiency when it comes to changing the orientation of a bit. The development of magneto resistive-based random access memory devices (MRAM) based on the voltage control magnetic anisotropy affect(VCMA) promise to mitigate this problem with magnetization switching at much lower current densities. The VCMA technique is a precessional based approach that requires precise timing of a voltage pulse to achieve the magnetization switching. Here we develop a numerical micromagnetics study for a 50nm perpendicular magnetic tunnel junction (MTJ) to investigate the timing of an applied voltage pulse on the spin dynamics of the free layer within the MTJ. Results are reported on the voltage-induced switching in the resonant (precessional) regimes at low temperature, while also adding thermal noise in the LLG equation to allow the evaluation of stochastic switching. Results reveal fast (< 1 ns) and ultralow-power (< 40 fJ/bit) write operations at voltages ~ 1- 2 V. It is shown that the model allows for optimization of write pulse timing and design considerations to achieve the lowest WER for the given MTJ parameters.

Traditional electromagnets become impractical when designed for small scale applications due to significant increases in resistive heating. To circumvent this, it would be beneficial to have a magnetic material which can be reversibly switched on/off by electrochemical hydrogenation utilizing an applied voltage. Fabrication of SmCo5 nanoparticles has seen increasing interest in data storage and biotechnological applications. This is due to the unique magnetic properties of SmCo5; with a high coercivity at room temperature it has the potential to be utilized as an on/off magnetic material. Therefore, it would be worthwhile to optimize current synthesis methods in order to improve this process. In attempting to accomplish this, a simultaneous reduction of Sm(acac)3 and Co(acac)3 is done within the presence of oleic acid and oleylamine. This is done with the assistance of Cu(acac)2 which has been previously shown to aid in forming the desired CaCu5 crystalline structure. Our samples were characterized using a variety of methods which include Electron Dispersive Spectroscopy, Transmission Electron Microscopy, X-Ray Diffraction, and SQUID magnetometry. In the future we hope to hydrogenate SmCo5 within an electrolytic cell by applying a voltage in order to observe switchable on/off magnetization.