Vitaliy Lomakin - US grants

NIRT: Opto-Plasmonic Nanoscope
Yeshaiahu Fainman, University of California at San Diego
0608863

Abstract

Intellectual Merit: This NIRT project focuses on the novel Opto-Plasmonic Nanoscope based on the recently observed transfer of the spatial phase of an ultrashort optical pulse into the phase of the excited surface plasmon polariton (SPP) wave packet. The Opto-Plasmonic Nanoscope resolution is determined by the SPP wavelength, which can be as much as 100 times smaller than the optical field wavelength, supporting resolution <100nm. The goal of this multidisciplinary proposal is to conduct basic research on the excitation, propagation, and detection of ultrashort pulse SPP waves focused to <100 nm, and to investigate effects that arise in the process of linear and nonlinear interaction of the focused SPP with bio-matter (e.g., protein molecules and live cells) attached to the surface. Specific research objectives include (i) excitation of SPP waves using 2D nanostructures for focusing to <100 nm; (ii) investigation of interaction of the SPP waves with various types of bio-matter arranged in different patterns on the surface; (iii) investigation of imaging and detection methods associated with the Opto-Plasmonic Nanoscope; (iv) investigation of label-free detection of protein molecules attached to the surface; (v) investigation of imaging of live cell dynamics on the surface with a resolution <100 nm; and (vi) planning innovative education and outreach projects with the Preuss School on the University of California, San Diego campus.

Broader Impacts: The research on the Opto-Plasmonic Nanoscope advances fundamental understanding and the ability to excite, control, and detect the SPP fields, and understanding of their interaction with biopolymers and live cells that has profound significance for the biomedical imaging. The proposed work will allow application of the SPP waves for advanced nanoscale biochemical, biological and medical imaging, and for sub-wavelength lithography. Innovative education and outreach projects with the Preuss School, designed for students in 6-12 grades coming from disadvantaged households will be carried out.

Data is at the heart of the digital revolution. Changing work habits, increasingly stringent electronic record-keeping mandates, and developments in the health care, energy, and retail sectors all suggest a growing demand for data storage and memories for the foreseeable future. Fast, low-power, ultra-high density, and non-volatile magnetic storage and memory systems are projected to accommodate the bulk of the global data storage needs for decades to come and spawn revolutionary data-intensive computing modalities along the way. Their timely development, however, critically depends on the availability of fast and accurate computational tools capable of simulating electromagnetic field and magnetization dynamics in complete magnetic data storage and memory systems. Unfortunately, current simulators are not up to this task.
This project focuses on the development of high-performance hybrid micromagnetic-electromagnetic simulators for modeling next-generation magnetic memory and data storage systems. The simulators leverage analytically preconditioned time-domain integral equation methods to solve the Maxwell and Landau-Lifshitz-Gilbert-Slonczewski equations, which govern coupled electromagnetic field and magnetization phenomena. To facilitate the analysis of such phenomena in complex systems involving billions of degrees of freedom, the simulators are implemented on massively parallel Central Processing Unit (CPU) and Graphics Processing Unit (GPU) computers. These simulators are used for the design of next generation magnetic random memory devices as well as bit patterned media and heat-assisted magnetic recording storage systems. Such advanced memory and storage systems are to be essential to future high-performance computing systems.

The ability to control spin dynamics is critical for enabling the operation of a host of magnetic devices. Exciting opportunities for manipulate spins are offered by directly using optical fields, as was recently demonstrated in experiments. This program introduces a comprehensive theoretical and computational framework for the characterization, modeling, and design of magnetic devices involving optical control of spin dynamics.

The proposed research has a theoretical physics, computational physics, engineering, technological, and educational component. The research provides fundamental understanding of optics driven spin dynamics, such as near Curie-point switching, all-optical switching, combined optical-spin transfer torque phenomena, and optics-induced spin waves. The program identifies new spin dynamics phenomena and structures that exhibit novel functionalities and the associated fluctuations and noise reduction particularly prevalent on the quantum scale. The research creates new methods and efficient simulators, including high-performance atomistic, mesoscale, and multiscale (hybrid atomistic-mesoscale) solvers. The research spawns new opportunities for modeling magnetic and optical devices and systems. The introduced multi-scale framework is used to address critical technological problems involving magnetic materials and devices employing optical control, such as energy assisted magnetic recording. The program includes an essential component of education of undergraduates and graduates, through courses and mentoring, in application of quantum mechanics to modern technology, particularly, micro- and nano-magnetics and electromagnetics. The work involves graduate and undergraduate students in research, and contributes to diversity.

The program has a range of broader impacts. The fundamental quantum mechanical models for magnetics contributes to the general field of quantum mechanics and its relation to practical devices. Various components of the high-performance methods can be used in other fields, such as biophysics, chemistry, and astrophysics. The proposed multi-physics solvers can be hybridized with solvers in other physical domains such as electrical/mechanical/fluidic modeling frameworks. The magnetic recording applications contributes to the development of data storage devices which are pervasive in modern society. The effort also develops a set of educational materials covering the proposed theory, simulation framework, and device study.

TECHNICAL SUMMARY:
New functionality in nanomagnetic devices requires control of magnetic order at the nanometer spatial scale and sub-nanosecond temporal scale. Many spin-based devices are still in their infancy and a thorough understanding of the underlying materials and electronic properties and their effect on device performance will be essential for future applications. With support from the Division of Materials Research, this Materials World Network project builds on a strong existing collaboration between the PIs Fullerton and Lomakin in the US and Ravelosona and Mangin in France and focuses on the study of magnetization manipulation in novel and complex magnetic heterostructures with perpendicular magnetic anisotropy. The goal of this project will be on understanding the fundamental physics of magnetically coupled nanostructured materials and their application for spintronic devices that will enable energy-efficient magnetic memory, magnetic oscillators and spin logic devices. In particular, the research team is interested in developing approaches for actively controlling the response of composite materials through a combined experimental and micromagnetic approach. Each materials system will be optimized to enable new phenomena such as low critical currents and ultra-fast reversal, resonant behavior at the nanoscale and strain modified domain wall motion.

NON-TECHNICAL SUMMARY:
New scientific discoveries in nano-magnetism are enabling a range of emerging nanotechnologies in the areas of data storage, memories, information processing and energy efficiency in computing. Combining nano-magnetism with advances in semiconductor science and technology, that have until recently ignored the spin of the electron, it gives rise to the field of spintronics. Spintronics is ushering in a range of new sensors, memories, logic devices and providing a spin-vision for the electronics of the future. This Materials World Network project has the transformative goal to provide the scientific underpinnings for next generation energy efficient, ultrafast, and ultrasmall spintronic devices. The project will promote active exchange of students, faculty and researchers between institutions and student researchers will be exposed to a broad range of materials challenges using novel and sophisticated equipment. A key component of the proposal is to foster collaborations between leading international, industrial, and national user-facility scientists. This will not only strengthen the scientific excellence and broaden the impact of the research, but it will also provide important educational and post-graduate career opportunities for both graduate and undergraduate students. This project will support innovative and sustainable partnerships between French and US research centers and institutions of higher education.

Modern science and technology increasingly rely on materials and devices utilizing unique properties of nanometer-scale composition. It is critical to be able to characterize such complex nanoscale configurations. A unique tool for characterization of nanoscale materials and devices is X-ray imaging, which can provide structural images with a high spatial and time resolution. In a typical X-ray imaging setup an X-ray source generates an X-ray beam that is scattered from the structure. The scattered X-ray beam is captured by a camera, and the resulting picture is processed to reconstruct the actual structure configuration. Due to their short wavelength X-rays can penetrate the structure's volume thus enabling not only two-dimensional but also three-dimensional imaging. X-ray imaging typically requires a significant computational effort for image reconstruction and often the computational time is longer than the time for performing the experiment. This project aims at closing this gap by creating high-performance computational tools for real-time X-ray imaging. The created software is to serve a broad community of synchrotron scientists. The developments in nanoscale imaging are intended to have applications in areas ranging from condensed matter physics to biology and chemistry of single molecules. A close interdisciplinary research effort between a computational researcher and an expert in X-ray scattering and material physics will benefit graduate students and postdocs working in these fields, and is likely to result in new and unexpected discoveries.

The goal of this research project is to create a high-performance computational framework for real-time X-ray imaging to be performed at X-ray scattering facilities. The X-ray imaging is to be accomplished using a new emerging three-dimensional X-ray imaging methodology called Coherent X-ray Diffractive Imaging (CXDI), which is based on computational phase-retrieval of the X-ray diffraction patterns. The proposed research includes algorithm and code implementation, practical application, and educational components. A set of algorithms for phase retrieval X-ray imaging are to be introduced, including methods for image representation and use of relevant constraints, methods for computing transformations between real to reciprocal spaces, and implementations on massively parallel computing systems. The research effort also introduces a virtual synchrotron framework utilizing computational methods to simulate experimental image reconstruction and provide required constraints, with magnetic nanostructures as a testbed. The developed computational framework is to be applied to real-time study of nanostructured materials and devices, such as nanoscale magnetic devices. The program integrates research and education by enhancing undergraduate and graduate courses on computational physics, micromagnetics and electromagnetics as well as providing graduate and undergraduate student training and contributing to diversity.