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Department of Physics
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Materials physics attracts a high fraction of physicists worldwide not only by virtue of the immediate technological impact of its advances, but also because the theoretical tools developed to understand emerging properties, such as superconductivity or ferromagnetism, can be applied in all other areas of physics. Our group has a very broad range of interests, from the synthesis of new materials with lower dimensionality to the use of atomic-size probes to understand the observed properties in terms of the most elementary atomic constituents. Our faculty and students devote a significant effort to the development of new experimental and theoretical tools that will make it possible to achieve a deeper understanding of materials properties, from electron holography to thermodynamics at the nanoscale.
Why Nanoscience & Materials at ASU ?
ASU is one of the few institutions worldwide where a true interdisciplinary critical mass has been achieved for materials research, with more than 100 faculty members scattered across departments and colleges working together on diverse nano-science and materials physics projects. Large-scale facilities for materials synthesis, nano-fabrication, ion-beam scattering, electron-microscopy, diffraction-physics, optical spectroscopy, and supercomputing are available on campus.
In particular, ASU is the world’s leading university in the field of sub-angstrom resolution electron microscopy, and will soon be home to the first table-top free electron laser for materials research. Students find that most materials science facilities they need to pursue their research are available on campus, and that each of these facilities are used by other students and faculty members who can provide the key insights to advance any project.
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Name
Contact
Expertise
Department Chair and Professor
Bennett works in experimental surface science to study ultra-thin films and self-assembled nanostructures.
480-727-9394
PSF 450A
Professor
Chamberlin is interested in the internal response of condensed matter. For example, we want to understand how the magnetization inside a material relaxes as a function of time after removing an applied field.
480-965-3922
PSF 425
Associate Professor
Culbertson's interests include Physics and Society.
480-965-0945
PSH 553
Professor
Drucker is a professor with interests in nanoscience and materials physics. His research group performs experimental and theoretical research to better understand the atomistic mechanisms of crystal growth on surfaces.
480-965-9658
PSF 342
Associate Professor
Dwyer is an electron microscopist with a backgrounds in scattering and condensed-matter physics. He is an Associate Professor in the Department of Physics at ASU.
480-965-2674
PSF 336
Assistant Professor
Erten is a condensed matter theorist. He obtained his doctorate at The Ohio State University in 2013 and has worked at Rutgers University and Max Planck Institute for the Physics of Complex Systems before joining ASU.
Associate Professor
Graves' interests focus on a new type of x-ray light source based on the collision of extremely short electron and laser pulses.
480-727-3441
Biodesign C 303
Assistant Professor
Hariadi's interests include the biological physics of molecular machines, mechanobiology, low-cost ultra-sensitive digital diagnostics, and the origin of life.
480-727-0064
BDI A120C
Assistant Professor
Karkare's research is at the interface of accelerator physics and nano-science.
Professor
Liu's interests are in nanoscience and materials physics.
480-965-9731
PSF 432A
Professor
McCartney's research interests include nanoscience and material physics.
480-965-4558
PSB 347
Professor
Menéndez leads a research program on the physics of semiconductor materials.
480-965-4817
PSB 349
Regents Professor
Nemanich's research group has applied advanced microscopy and spectroscopy techniques to characterize the growth and properties of thin film interfaces and nanostructures.
480-965-2240
PSB 353
Associate Professor
Peng's expertise is in first principles density-functional theory calculations and material science.
480-727-5013
WANER 340N
Professor
Ponce's current interest is in the understanding of the materials properties of III-V nitrides, and their correlation to growth and to device performance for solid state lighting.
480-965-5557
PSF 344
Associate Professor
Qing is a joint assistant professor of the Department of Physics, and the Center of Bioelectronics and Biosensors in the Biodesign Institute. He is also a member of the Center of Biological Physics at ASU.
480-965-9261
PSF 433A
Professor
Rez's background is in the theory of electron scattering as applied to electron microscopy and analysis. His studies include the development of electron energy loss spectroscopy and the microstructure of kidney stones.
480-965-6449
PSF 325
Professor & Associate Chair of Space
Ros' research interests are in experimental biophysics and nanoscience.
480-727-9280
PSF 359B
Assistant Professor
Professor
Schmidt's interests include quantum Monte Carlo, many-particle theory, nuclear physics, cold atoms, and femtosecond pulse X-ray scattering.
480-965-8240
PSF 242
Assistant Professor
480-965-6073
Regents Professor
Smith specializes in the development, applications, and advancement of atomic-resolution electron microscopy.
480-965-4540
PSB 343
Associate Professor
Sukharev's research interests include computational nano-optics; coherent control, and physics of light-matter interaction in strong and ultra-strong coupling regimes.
480-727-1398
WANER 340M
Assistant Professor
480-727-2772
Professor & Associate Chair of Academics
Treacy received his PhD in physics from Cavendish Laboratory, Cambridge in 1979. His interests are: modeling hypothetical zeolite frameworks; the study of disordered materials by Fluctuation Microscopy.
480-965-5359
PSB 249
Founding Director
Venables retired from his tenured post in 2008. He was rehired increasingly part-time in connection with the PSM in Nanoscience, for which he is the founding program director.
480-965-0355
PSB 470
Research Professor
Weierstall is working on bio-sample delivery methods for X-ray Free Electron Lasers and Synchrotrons. He is a member of the NSF BioXFEL Science and Technology Center.
480-965-0426
PSF 248
John M. Cowley Center for High Resolution Electron Microscopy
As a global leader in high resolution electron microscopy, ASU plays an important role characterizing critical properties of materials. This facility houses a dozen electron microscopes that can probe the physical, electronic and chemical structure of matter on an atomic scale. Instruments & techniques include Ion Milling; Electron Microprobe; Scanning Electron Microscopy; Transmission Electron Microscopy; Scanning Transmission Electron Microscopy; and Aberration Corrected Electron Microscopy.
View research by individual faculty
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Dr. Menendez
The Menéndez group specialized in semiconductor physics, with emphasis on experimental optical properties probed with techniques such as photoluminescence, spectroscopic ellipsometry, and Raman scattering. Recent work has focused on the study of new materials synthesized at ASU, most notably group-IV alloys and ultrahighly-doped semiconductors.
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Dr. Nemanich
Dr. Nemanichs research involves an interdisciplinary group of researchers dedicated to the study of semiconductor surfaces, interfaces, and processing, with a focus towards electronic and optoelectronic applications. Students from physics, electrical engineering, and materials science work together under the direction of Dr. Robert J. Nemanich
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Dr. Drucker
In the Drucker group we try to understand the atomic processes leading to crystal growth. This fundamental knowledge enables engineering materials and nanoscale architectures not found in nature that may have novel properties enabling next generation technologies. Our current focus is on 2-D materials, which can be grown as covalently bonded single-atom or single unit cell thick layers such as graphene, hexagonal boron nitride (h-BN) or transition metal dichalcogenides such as MoS2.
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Dr. Treacy
Dr Treacy has research efforts in two areas. The first is in electron diffraction physics, where new electron microscopy methods are developed and explored for determining the structures of materials. At present, the emphasis is on amorphous materials. The second area is the study of zeolite structures and their topologies. This topic lives at the rich interface between physics, chemistry, mathematics, computation and algorithms, and structural engineering. Many interesting collaborations arise. The figure shows an interferometric diffraction pattern (right side). The fading of fringes tells us about decoherence arising from beam-induced atom motions.
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Dr. Chen
Dr. Chen specializes in experimental Condensed Matter Physics. His recent research focuses on spin-polarized currents, pure spin currents, super-spin currents, and spin caloritronics to explore novel physics and to engineer new types of devices for future electronics with ultralow power consumption and ultrahigh density. The new type of electronics, taking advantage of both charge and spin of conduction electrons, can be driven by electric field, magnetic field, or thermal gradient. Please visit his group webpage for more information.
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Dr. Fischer
Dr. Fischer research is mainly focused on the study of optical and structural properties of III-nitrides for optoelectronic and photovoltaic applications. He is currently working on an ARPA-e project for the development of high-temperature thermionic InGaN solar cells. He is specialized in temperature-dependent carrier lifetime measurements, cathodoluminescence, photoluminescence, reflectance/transmittance, X-ray diffraction, and ellipsometric spectroscopy.
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Dr. Sukharev
The goal of the Sukharev research group is to advance fundamental understanding of light-matter interaction at subwavelength scale. The group utilizes both classical and quantum theories to scrutinize general physical aspects of optical properties of various materials ranging from dispersive dielectrics to nonlinear crystals. Such systems exhibit interesting phenomena, some of which we use to investigate how aggregates of atoms and molecules behave near interfaces with nanomaterials. The group has close collaborations with experimental and theoretical groups in the US (Northwestern University, UCLA, AFRL, University of Pennsylvania), Israel (Tel Aviv University, Bar-Ilan University), and France (University of Paris SUD, Paul Pascal CNRS research laboratory).
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Dr. Bennett
The Bennett group studies self-assembled surface nanostructures using a variety of techniques, including Scanning Tunneling Microscopy (STM), Low Energy Electron Microscopy (LEEM), UHV-Transmission Electron Microscopy (UHV-TEM), Atomic Force Microscopy (AFM), Magneto-transport and Electron Beam Lithography (EBL). The Figure shows insitu resistivity measurements of metallic nanowires on a silicon surface, using an STM (panel a,b). These nanowires are only 3nm wide, and are prefect single-crystals, as seen in the cross-section TEM image (panel c).
Research Highlights
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ASU physicists achieve 10-fold improvement vibrational mapping
It has very recently become possible to use a focused beam of high-energy electrons to map the vibrational modes in free-standing nanomaterials. ASU's LeRoy Eyring Center for Solid State Science houses the first-of-its-kind instrument capable of such experiments (the Nion UltraSTEM 100, pictured). In a recent work published in Physical Review Letters (117, 256101), ASU physicist Christian Dwyer, in collaboration with scientists from LE-CSSS and Nion Co., has demonstrated a spatial resolution of better than 2 nm – a 10-fold improvement on previous efforts. These results open the door to nanometer-scale electron-beam mapping of vibrational modes as a powerful tool for nanomaterials analysis.
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Nanoscience & Materials: Conduction of a typical resistor
Conduction of a typical resistor is described by the Ohm’s law, where current (I) is linearly proportional to applied bias voltage (V) with conductance (I/V) as the coefficient. The more sensitive differential conductance (dI/dV) gives the same constant value of I/V. However, at some interfaces between different materials, the conductance varies depending on V and there is a peak (anomaly) in dI/dV at V = 0, called zero bias anomaly (ZBA). Many ZBAs are due to novel physics induced at the interface and have been utilized as crucial signature evidence to identify some of the recent exciting physics such as topological insulators and superconductors, Majorana fermions, nodal superconductivity, and decagonal quasicrystals. In this work, the Chen Lab in Physics has demonstrated that ZBAs can be observed in conventional superconductors and the observed ZBAs cannot be suppressed by a highly spin-polarized current. By systematically varying the size of the interface, they show the evolution of the ZBAs from conductance dips and determine that the ZBAs are not intrinsic to the SCs but are due to a resistance change induced by the critical field of large interfaces. This work demonstrated that it is crucial to vary the interface systematically to identify the origin of the ZBA. . Courtesy of Tingyong Chen, from: Gifford et al., J. Appl. Phys., 120, 163901 (2016).
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Nanoscience & Materials: Spintronics requires spin of conduction electrons
Spintronics requires spin of conduction electrons aligned in a direction with the degree of the alignment measured by spin polarization. Despite its importance, very few techniques can measure spin polarization of a material. Andreev reflection spectroscopy (ARS) utilizes a spin configuration of a Cooper pair in a superconductor (SC) to detect the spin polarization. Previously, only conventional SCs have been utilized in ARS, with a typical Tc below 10 K and a critical field up to 1 kOe. Unconventional SCs can have much higher Tc up to 160K and much larger critical field of over 122 T, which can be utilized to explore many spin-related phenomena in a wide temperature and magnetic field range. However, spin detection using an unconventional SC has never been demonstrated in ARS. In this work, the Chen lab in Physics has, for the first time, shown that the spin polarization of a highly spin-polarized material can be measured using an unconventional Fe SC up to 52 K and the measured spin polarization is the same as that measured by a conventional SC. Courtesy of Tingyong Chen, from: Gifford et al., AIP Adv., 6, 115023 (2016).
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Nanoscience & Materials: Polarization fields and stacking disorder in InAs nanopillars
Former Physics graduate student Luying Li returned to continue her collaboration with Physics faculty Dave Smith and Molly McCartney and address the possibility of detecting polarization fields across polytype interfaces in InAs nanopillars using the technique of electron holography. Part of the investigation included studying the local crystal polarity on an individual column-by-column basis. The false color image shows an aberration-corrected electron micrograph from an InAs nanopillar with irregular stacking disorder, also demonstrating that resolution of individual In and As atomic columns can be achieved.
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Nanoscience & Materials: Multigrain magnetic domains in thin spinel ferrite films
Materials graduate Desai Zhang, working with Physics faculty Molly McCartney, used the technique of electron holography to resolve a longstanding question about the multi-grain nature of magnetic domains in thin spinel ferrite films: a) Lorentz image; b) phase image; b) map of magnetic domains; d) domain overlay on Lorentz image demonstrating the multigrain domains. The composite image was featured as a cover illustration in a recent issue of the Journal of Applied Physics.
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Nanoscience & Materials: Spin polarization gets tuned
In conventional electronics, only an electron current is utilized, whereas a spin-polarized electron current is utilized in spintronic devices. The device performance then depends crucially on the value of the spin polarization. Thus, a current with controllable spin polarization can be used to tune the device. However, the spin polarization depends on the specific band structures of the material and cannot readily be changed. In this work, physics faculty Tingyong Chen and Dave Smith have shown that in a Co/Cu multilayer structure consisting of 1 nm Co and 1nm Cu with large giant magnetoresistance (GMR) value of close to 120%, the spin polarization can be continuously controlled by a modest external magnetic field. This result is the first demonstration of continuous control of the spin polarization of current by a magnetic field. Courtesy of Tingyong Chen, from: J. A. Gifford, et al., Appl. Phys. Lett. 108, 212401 (2016)
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Nanoscience & Materials: Polarization fields and stacking disorder in InAs nanopillars
Former Physics graduate student Luying Li returned to continue her collaboration with Physics faculty Dave Smith and Molly McCartney and address the possibility of detecting polarization fields across polytype interfaces in InAs nanopillars using the technique of electron holography. Part of the investigation included studying the local crystal polarity on an individual column-by-column basis. The false color image shows an aberration-corrected electron micrograph from an InAs nanopillar with irregular stacking disorder, also demonstrating that resolution of individual In and As atomic columns can be achieved.
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Nanoscience & Materials: Plasmons in silver islands
Dexin Kong, a recently graduated PhD student working in the Drucker group, measured the optical response of epitaxial Ag islands grown on Si(100). These islands host localized surface plasmon resonances (LSPR) that are oscillations in their charge density. The LSPR modes that oscillate parallel to the Si surface have different frequencies than those that oscillate perpendicular to the Si surface. A theoretical model was developed that allowed identification of these modes. The figures show scanning and transmission electron micrographs of the Ag/Si(100) islands and a comparison of the real and imaginary parts of the dielectric functions of Si and the experimentally measured and simulated Ag/Si(100) pseudodielectric functions. This work recently appeared in the J. Appl. Phys., 118, 213103 (2015).
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Nanoscience & Materials: How doping affects size in semiconductors
Doping a semiconductor induces a change in its lattice parameter. This change is caused not only by the different sizes of the impurity and host atoms, but also by the strain developed when the occupation of electronic energy bands is modified. While these ideas are conceptually simple, experimentalists and theoreticians alike have struggled for decades to separate the size and electronic effects. Following up on the most significant earlier developments, which focused on doped Si, a Physics-Chemistry ASU team collected data for n-type Ge doped with novel precursors and discovered trends as a function of the donor species in both Ge and Si that hold the key to resolving the doping dependence of the lattice parameter into its two fundamental physical components. This work was published by Physical Review B (doi:10.1103/PhysRevB.93.041201) and highlighted as an Editors' Suggestion.
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Nanoscience & Materials: Hypothetical Zeolites
Zeolites are important silicate-based materials that are related to sand, i.e. quartz. Although their structures are built from the same corner-sharing SiO4 tetrahedra as quartz, they contain pores and tunnels that can absorb water and small hydrocarbon molecules (very much unlike quartz). This microporosity gives zeolites enormous internal surface area, enabling a rich and diverse array of chemical uses. For example, about half of the gasoline in the US has been in contact with a zeolite. At present, there are 231 known zeolite Framework Types. By treating zeolites as periodic graphs, we have discovered many millions of low-energy hypothetical topologies in the computer. In theory, there is an infinite number of hypothetical zeolites frameworks types. The mystery is “Why are so few of the hypothetical topologies found in nature?” The key appears to be framework flexibility. All of the known zeolite frameworks are flexible if we treat the SiO4 tetrahedra as being ideal and rigid, allowing flexing only at the vertices. In other words, low framework energy is no enough, the framework must be able to “breathe” too. This important property allows us to identify the smaller subset of realizable hypothetical frameworks within our database. Z. Krist., 212 768–791 (1997); Microporous & Mesoporous Materials 74 121–132. (2004).
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Electron Diffraction Physics: Electron Scattering Decoherence in Glasses
The structures of amorphous materials are hard to determine. We know that they are highly disordered, but atoms cannot get arbitrarily close to one another, so we know that there is strong short-range order. The open question is “What is the length range of this order?” Recent graduate student Aram Rezikyan studied amorphous silicon and carbon using the Fluctuation Electron Microscopy (FEM) technique. By studying random diffraction speckle in images (measured by the normalized intensity variance V(k)) as a function of diffraction vector, and beam voltage, he was able to probe the role of electron beam damage in the disruption of the amorphous structure. Such atom motions give rise to an effective electron decoherence. It turns out that atoms move under the electron beam much more than we thought. Microscopy and Microanalysis 21 1455–1474 (2015).
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SPECTROSCOPY IN THE ELECTRON MICROSCOPE
Combining spectroscopy with the high spatial resolution in the electron microscope is a powerful tool to investigate chemistry, including local bonding changes, at the atomic scale. Traditionally it has only been possible to perform the equivalent of UV and soft X-ray spectroscopy with energy resolution of just under 1 eV. Our new Nion electron microscope, with a specially developed monochromator, gives us 10 meV energy resolution. This allows us to do the equivalent of optical and infrared spectroscopy, still at the nm scale. The spectrum on the left comes from a guanine fish scale. All the peaks arising from vibration of hydrogen attached to C or N atoms are distinguishable. Since the presence of hydrogen is generally inferred in electron microscopy, not directly directed, this represents a major advance for characterization of polymers and materials of biological origin.
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Crystal structures of noncentrosymmetric materials
Crystal structures of noncentrosymmetric materials don’t have inversion symmetry, a common feature observed in most materials. The lack of the inversion symmetry results in an anti-symmetric Dzyaloshinskii-Moriya interaction, which competes with the usual Heisenberg exchange interaction and plays a key role in creating non-collinear magnetic spin structures such as skyrmions in these materials. Furthermore, in superconductivity, the lack of the inversion symmetry may produce an anti-symmetric Rashba-type spin-orbit coupling, which allows mixing of the spin-singlet and the spin-triplet Cooper pairing states, as opposed to the pure spin singlet state in most of the known superconductors. Collaborating with USTC, JHU and UNH, physics faculty Tingyong Chen and his graduate students have shown that Rh2Mo3N, a noncentrosymmetric material with β-manganese structure is a superconductor with critical temperature Tc ≈ 4.3 K. Andreev reflection spectroscopy measurements using both normal metal and half metal show conclusively s-wave pairing with an isotropic gap. Courtesy of Tingyong Chen, from: Wensen Wei, et al., Phys. Rev. B 94, 104503 (2016).
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Nanoscience & Materials: Spintronics takes advantage of both charge and spin of conducting electrons
Spintronics takes advantage of both charge and spin of conducting electrons so materials that can conduct electrons with only one spin orientation are ideal for spin source. These materials are called half metals (HM) and have a spin polarization of 100%. Thus far, very few materials have exhibited close to 100% spin polarization and they are not suitable for spintronic devices because of their low spin transport effects. Recently another interesting class of materials, which have a semiconducting or insulating gap in one spin channel and zero gap in the other at the Fermi level, have been discovered. These spin-gapless semiconductors (SGS) have very unique and remarkable properties such as voltage-tunable spin polarization, the ability to switch between spin-polarized n-type and p-type conduction, high spin polarization, and high carrier mobility. In this work, collaborating with UNL and South Dakota State University, physics graduate students Dongrin Kim and Gejian Zhao from Prof. Chen’s group have shown that a SGS, CoFeCrAl, can have very high spin polarization of 68%, suitable for spintronics. Courtesy of Tingyong Chen, from: Jin et al., Appl. Phys. Lett., 109, 142410 (2016).