Study of spin transport has seen an explosion of interest and growth reflecting the richness of the underlying physics and the potential for technological application. IRG-3 is exploring a new frontier in spin transport by moving beyond the regime of diffusive transport. Nonlinear magnetic dynamics will arise from non-adiabatic torques in sharp textures, collective transport in dynamic textures, and large spin fluxes. IRG-3 combines theory, modeling and ab-initio materials prediction with expertise in spin-thermal transport, diverse magnetic and semiconductor materials growth, and high sensitivity spin detection to provide foundations for new approaches to manipulation and control of spin transport.

IRG-3 Faculty

• Joseph Heremans, Professor of Mechanical & Aerospace Engr. (Co-leader)
• Fengyuan Yang, Assoc. Professor of Physics (Co-leader)
• Ezekiel Johnston-Halperin, Assoc. Professor of Physics
• P. Chris Hammel, Professor of Physics
• Roberto Myers, Assoc. Professor of Materials Science Engineering
• Wolfgang Windl, Professor of Materials Science Engineering
• Michael Flatte, Professor of Physics, University of Iowa
• Yaroslav Tserkovnyak, Professor of Physics, UCLA

Organic Optoelectronic Interfaces relies on a combination of experimental and theoretical approaches to determine the key structure-property relationships associated with interfaces in a new generation of organic optoelectronic devices. By combining its expertise in molecular synthesis, film growth, transport, spectroscopy, computation, and modeling, the IRG aims to fabricate and characterize organic-insulator, organic-organic, and organic-metal interfaces with enhanced performance in field effect transistors (OFETs) and photovoltaic cells (OPVs).

IRG 1: Random Organization of Disordered Materials combines researchers from Chemistry, Civil and Chemical Engineering, Mathematics and Physics to investigate new principles for organizing and controlling the microstructure of multiscale materials. The IRG builds on the remarkable discovery of the Random Organization Principle, pioneered by NYU MRSEC investigators, by which systems driven out of equilibrium evolve towards absorbing states in which dynamic rearrangement ceases. IRG 1 explores the structures and correlations that arise in granular, multicomponent and active materials under external and internal driving, particularly those of the absorbing states, seeking to optimize material properties such as yield strength and photonic band structure, and to develop active materials such as optically

reconfigurable colloids and active extensile viscoelastic liquids.

Faculty and Senior Participants: Jasna Brujic, Paul M. Chaikin, Aleks Donev, Alexander Grosberg, Magued Iskander, David J. Pine, Stefano Secanna,  Nadrian C. Seeman, Mike J. Shelley, Eric Vanden-Eijnden

 

 

 

Senior Investigators: Dennis E. Discher & Andrea Liu IRG Leaders; Paul A. Heiney, Randall D. Kamien, Michael L. Klein, Virgil Percec, Shu Yang IRG-2 will collaborate to synthesize sstrongi-flexible, functional cylinders composed of dendrimer-based polymers & self-assstrongbling block copolymers. The goal is to understand the interplay between soft structure & function and thereby develop cylinders whose meso-conformations can be controlled to generate mechanical motion and cylinders that can be arrayed as flow-responsive nano-reactors.

IRG1, Designing Functionality into Layered Ferroics, will showcase materials discovery by design for electric field control of electronic, optical, magnetic and structural response of materials starting from the level of atoms. The goal is to design and discover fundamental new mechanisms and material classes of acentric layered oxides with strong coupling to spin, charge, and lattice degrees of freedom. An unprecedented expansion of ferroic families in layered oxides – a vast and largely unexplored materials class with unique control knobs in chemistry, topology, and geometry – will enable the design of ferro- & ferri-electricity, magnetoelectricity, multiferroicity, and gradient-driven effects. We will counterpoise competing phases with colossal properties to transform otherwise nonpolar materials into strongly polar ones and will couple electrical, magnetic and structural order parameters. Group theory, materials informatics, first-principles DFT, model Hamiltonians, and phase-field modeling will predict new ferroic systems and guide experimental efforts. Potential new technologies include room temperature electric field control of ferromagnetism, highly nonlinear optical materials, high temperature piezoelectrics, GHz electronics, and electric field control of correlated phenomena.

The Materials Research Science and Engineering Center (MRSEC) at the University of Alabama features a multidisciplinary research program built on a solid foundation provided by the existing Center for Materials for Information Technology (MINT). The MRSEC supports interactive research through two interdisciplinary research groups. The group which focuses on the relationship of microstructure and magnetic properties carries out fundamental measurements on materials systems which have potential applications in future magnetic recording systems. Of particular interest are nitrogenated iron based alloys, high magnetization iron nitride films and giant magnetoresistance thin films. The group which concentrates on the preparation and dispersion of magnetic nanoparticles is directed to develop new synthetic methods for the preparation of magnetic particles and to gain a fundamental understanding of magnetic dispersions. The MRSEC is housed in the same research building where the MINT Center is located and shares a number of central facilities with the existing center. Collaboration with industry is extensive and well established by the MINT Center. The MRSEC provides seed funding for exploratory research and emphasizes minority recruitment and interdisciplinary training. A major component of the educational goals is to attract, retain and train more students in a technologically important area where, as demonstrated by the success of graduates, excellent jobs are available. The close association with the Historically Back Colleges and Universities (HBCU) in the South is utilized to enhance current outreach programs that support minority students and faculty. The center currently supports 7 faculty, 5 post-doctoral assistants, and 5 graduate students. The MRSEC is directed by Professor William Doyle.

Mission:

This IRG will investigate metamaterials- particularly chiral, quasiperiodic and hyperbolic MMs – and MM-inspired structures with unusual properties such as near-field plates and hyperlenses, and develop understanding applicable to communication, sensing and imaging.

Research Overview:

Metamaterials (MMs) are homogeneous artificial mixtures, that is, composites for which the distance be-tween neighboring inclusions is significantly smaller than the wavelength of interest. Recent advances in assembly methods, micro- and nanofabrication, coupled with an increased understanding of their electro-magnetic (EM) response have led to the synthesis of composites whose behavior is quite unlike those of natural materials. Negative refraction, cloaking, plasmonic hot-spots, super-resolution, and high-frequency magnetism are but a few of the terms that were introduced into the scientific vocabulary during the past decade following continuous progress in MMs research. This IRG program provides a comprehensive approach for the development of novel composites; particularly chiral, quasiperiodic and hyperbolic MMs; and MMs-inspired struct

ures with unusual physical properties, such as near-field (NF) plates and hyperlenses. The research combines state-of-the-art self-organized, epitaxial growth and lithographic techniques with the development of innovative NF experimental tools, together with a strong theoretical basis and a multiplicity of characterization methods.

An example of the way recent breakthroughs in metamaterialsresearch has opened up new frontiers in photonics is the recent demoonstration by Shalaev and coworkers at Purdue that the high losses normally present in plasmonic MMs can be overcome by incorporating gain media within the composite. In another example, at the University of Michigan, Merlin and colleagues have devised novel structures such as near-field plates for superresolution imaging. Based on these and related  breakthroughs, IRG2 explores this newly opened frontier of MMs as a partnership between Michigan and Purdue, with additional collaborations from the University of Texas and Wayne State University.

IRG2 makes, models, and studies autonomous motors and pumps that convert the free energy of local chemical, optical, thermal, and acoustic fields to motion. In addition to providing information about the mechanisms of motility, the study of synthetic motors helps address fundamental questions about emergent collective behavior at low Reynolds number and on length scales from sub-nanometers to hundreds of micrometers. Much of our understanding of active matter derives from continuum theories coupled to observations of complex biological swimmers or externally driven colloidal particles. The observation in abiotic systems of many behaviors previously associated with purely biological processes suggest intriguing questions as to the underlying principles that govern both. The IRG2 team pursues a bottom-up approach to understanding motility, sensing and emergent collective behavior in autonomously driven synthetic systems by combining theory and numerical modeling with the synthesis and experimental study of new classes of motors.

Important findings in IRG2 include the discovery of synthetic autonomous nanomotors and micropumps driven by catalysis and light, elucidation of their self-electrophoretic propulsion mechanisms, discovery of complex swarming, predator-prey, and spatio-temporal oscillatory behavior in colloidal motor assemblies, engineering of chemotaxis, steering, and cargo delivery in motor systems, demonstration of catalytically powered motion at the nm scale of individual catalyst molecules, including (non-motor) enzyme molecules, characterization of momentum transfer by active swimmers at length scales from colloidal to molecular, and discovery of two new acoustic motor propulsion mechanisms that are tolerant of electrolyte solutions and gel media, including the interior of living cells.

The vision of this IRG is to drive, “Transformational improvement in solar energy conversion through fundamental materials innovation.”  There are two aspects to its strategy for realizing this vision. The first involves its core research mission directed at “Understanding, controlling and exploiting the unique properties of group IV nanostructures in photovoltaic architectures.” The second is to be an enabler acting as a “nucleation and growth point for a broad range of materials research in solar energy conversion.” The research program is directed at creating technology discontinuities that significantly shorten the time scale for solar energy to make a major contribution to world energy production. Critical to success is the Center’s integration of unique nano materials synthesis, novel characterization and computational interrogation. 

The vision of IRG-1, Electrostatic Control of Materials, is to use a set of new techniques for electrostatic manipulation of charge carrier density at material surfaces as a universal platform to probe and control electronic properties in novel materials. Recently developed methods based on ionic liquids, ionic gels, and solid electrolyte structures are being used to generate unprecedented charge densities in a variety of materials, up to significant fractions of an electron per unit cell, enabling dramatic property modification. Opportunities include reversible control of magnetic order and properties, fine-tuning of insulator-metal and superconducting transitions, novel electronic and opto-electronic device concepts, discovery of new electronic and magnetic phases, and determination of the limits of transport in new materials. The IRG is exploring three classes of materials of exceptional current interest as test cases: (i) organic conductors; (ii) metal chalcogenides; and (iii) complex oxides.