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Institute for Electronics and Nanotechnology (IEN)

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End date: 2023 × Start date: 2023 × Has files: Yes × Type: Moving Image ×

Publication Search Results

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    An engineer’s perspective on antiferromagnetic spintronics
    (Georgia Institute of Technology, 2023-03-07) Rakheja, Shaloo
    Antiferromagnets (AFM) materials have ordered spin moments that alternate between individual atomic sites, which gives them a vanishing macroscopic magnetic signature and picosecond intrinsic timescale. In his 1970 Nobel Lecture, Louis Néel claimed that antiferromagnets are “extremely interesting from theoretical standpoint, but do not seem to have any applications.” Traditionally, AFM materials have played a secondary role to ferromagnets, which are used as active elements in commercial spintronic devices like magnetic sensors and non-volatile magnetic memory. However, it was recently suggested that spin transfer torque could in principle be used to manipulate the magnetic order in AFMs, leading to either stable AFM order precessions for their use as high-frequency oscillators, or switching of the AFM order for their use as magnetic memories. My presentation will focus on recent theoretical and experimental developments in the field of spintronic devices using antiferromagnets as their active elements. I will specifically talk about two unique AFM materials, Cr2O3, a single-phase magnetoelectric material that can be manipulated solely with electric fields and the Weyl semi-metal Mn3Sn in which spin torque can induce chiral spin rotations. Cr2O3-based ferromagnet-free random access memory has been experimentally demonstrated, while in the case of Mn3Sn, spin torque driven dynamics were found to induce chiral oscillations, from the megahertz to the terahertz frequency range. These materials can overcome the central challenge of manipulating and reading the AFM’s order parameter via microelectronics compatible circuitry, thus allowing us to develop antiferromagnetic spintronics along a similar route as ferromagnetic spintronics. I will conclude my talk by summarizing the limits, challenges, and opportunities of AFM spintronics for future technologies such as high-density, secure nonvolatile memory, compact narrowband terahertz sources, and spike generators.
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    Atomically-Precise Materials Prepared Using Ion Soft Landing
    (Georgia Institute of Technology, 2023-02-21) Johnson, Grant E.
    Scientific challenges that underlie efficient energy storage, chemical conversions and separations, and quantum computing may be addressed using unconventional mass spectrometry techniques that provide unprecedented molecular-level insight. Novel materials not obtainable through conventional synthesis methods may be prepared using a versatile deposition approach known as ion soft landing. A wide range of polyatomic ions, clusters, and nanoparticles with precise composition and charge may be delivered to supports with predetermined coverage and kinetic energy, thereby circumventing the heterogeneity, contamination, and aggregation that often confound characterization and modeling of materials. In this presentation, I will illustrate several recent applications of ion soft landing in energy related research. Precisely controlling the size, shape, and elemental composition of alloy nanoparticles is central to developing catalysts that efficiently promote reactions. Magnetron sputtering combined with gas aggregation prepares bare ionic nanoparticles with unique composition and morphology that are size-selected and deposited onto electrodes. For energy storage, sub-nanometer metal oxides known as polyoxometalates are leading candidates for use in advanced molecular batteries and supercapacitors. Insights are obtained into how the redox properties of polyoxometalates evolve with metal substitution by leveraging the atom-by-atom selectivity of ion soft landing. The impact of substrate and intermolecular interactions on the vibrational properties of polyoxometalate-based molecular qubit arrays is investigated, as is the influence of the size and stoichiometry of ionic liquid clusters on the desolvation, reduction, and separation of metals ions at electrodes. Combined with state-of-the-art characterization techniques and high-level theoretical modeling, ion soft landing is providing transformative insights into the properties of materials in the size regime where each atom counts.
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    LEEFT with Nano for Water Disinfection
    (Georgia Institute of Technology, 2023-02-07) Xie, Xing
    Water is a basic human need. Nevertheless, more than 10% of the world’s population lacks access to safe drinking water. An effective water disinfection method is still not readily accessible to these people. In developed urban areas, water is typically disinfected in a centralized facility through chlorine-based methods that inevitably generates harmful disinfection byproducts. In addition, current water disinfection systems are vulnerable to natural disasters. Next-generation water disinfection should minimize the use of chemicals, the consumption of energy, and the impact on the environment, while having high resilience for different application scenarios. The recently developed water disinfection approach based on locally enhanced electric field treatment (LEEFT) has a great potential to transform current water disinfection strategies and systems. The LEEFT is a physical treatment process that aims to utilize a strong electric field to disrupt cell membranes and thus inactivate pathogens. The electrodes installed in a LEEFT device are typically modified with one-dimensional nanostructures, such that the electric field is greatly enhanced locally near the tips of the nanostructures. LEEFT can potentially be applicable at all scales, from portable devices to point-of-use household units and from distributed community-scale treatment clusters to centralized treatment plants. This talk will cover the recent progress on the development of the LEEFT technology.