Top ⇑Materials Engineering

Principal Investigator: Douglas Chrisey

Tulane Group Members:

Our research interests are wide ranging and include the novel laser fabrication of thin films and coatings of advanced materials for electronics, sensors, biomaterials, and for energy storage. The new materials were used in device configurations for testing and typically had an improved figure-of-merit. He is considered one of the pioneers in the field of Pulsed Laser Deposition and was the lead inventor of MAPLE processing technique (matrix assisted pulsed laser evaporation). He is currently publishing in areas of metallic nanoparticle fabrication, biosensing, bionanotechnology, tissue engineering, stem cell processing, ceramics, and polyamorphism.

Top ⇑Surface Science

Principal Investigator: Ulrike Diebold

Tulane Group Members:

During the last thirty years, tremendous success has been made in the development of theoretical and experimental techniques for investigation of solid surfaces. The geometric, electronic and vibrational structure as well as the chemistry and reactivity of solid surfaces can now be investigated with unprecedented detail. Fundamental knowledge from these investigations has big impact in such diverse fields as semiconductor industry and catalysis. Our research focus is the investigation and modification of surfaces of materials which have not been extensively investigated with surface science techniques; especially metal compounds such as oxides, nitrides, and silicides.

Current projects of our surface science group include the surface geometric structure of single-crystalline oxides, adsorption of molecules, and ultrathin film growth. State-of-the art ultrahigh vacuum equipment is used for the experimental part of the research. In-situ Scanning Tunneling Microscopy and low-energy electron diffraction is used for studying surface morphologies and atomic structure. Spectroscopic techniques such as laboratory-based x-ray photoelectron spectroscopy and high-resolution photoemission studies at synchrotron radiation sources complement the research program.

Top ⇑Experimental Solid State Physics

Principal Investigator: David L. Ederer

Tulane Group Members: Yinwan Li & Tim Schuler

Professor David L. Ederer was a senior staff scientist in the Center for Atomic, Molecular and Optical Physics at the National Institute of Standards and Technology (NIST), for almost thirty years. He came to Tulane in January 1992 to launch a new program in experimental solid state physics with the Center for Advanced Microstructures and Devices (CAMD) in Baton Rouge, as a focal point. Ederer carries out research on transition metals and rare earth materials at the Advanced Light Source as well, using soft x-rays to elucidate the electronic properties of complex and highly correlated materials such as high Tc superconductors. Ederer, a fellow of the American Physical Society, is an internationally recognized expert in the use of synchrotron radiation for research in atomic, molecular, and solid state physics. His research in atomic, and condensed matter physics, as well as instrument design has resulted in over one hundred and fifty papers.

Recent topics of research have included doped manganate systems, the superconducting perovskite Sr2RuO4 system and multi-layered variants, and magnetically doped semiconductors with particular focus on half-metallic behaviour.

Top ⇑Photonic Materials & Devices

Principal Investigator: Matthew Escarra

Tulane Group Members:

Starting in Fall 2013, the Escarra group will explore novel photonic materials and devices based on quantum phenomena and optical nanostructures. One core research interest in this group will be the development of improved mid-infrared light sources and detectors based on quantum cascade semiconductor heterostructures. These devices, such as the quantum cascade laser, have applications ranging from medical diagnostics and environmental sensing to industrial process monitoring and homeland security.

A second core research thrust will pursue new approaches to achieving high efficiency solar energy conversion. This research area will focus on novel photonic micro/nanostructures for sculpting the flow of light in photovoltaic modules, leading to improved light absorption and more efficient use of the full solar spectrum. In addition to pursuing these optical approaches, the development of high performance III-V semiconductor solar cells is also an important part of this research area.

The work in this group will involve optical and device physics simulations, micro/nanofabrication, and related material and device characterization.

Top ⇑Thin-Film and Nanostructure Materials

Principal Investigator: Dae Ho Kim

Tulane Group Members:

The primary research interest of the thin-film group is in understanding the physics governing various properties in epitaxial films of metal-oxides for future device applications. The materials under focus are transition metal oxides (or complex-oxides) exhibiting wide variety of properties, such as ferromagnetism, ferroelectricity, piezoelectricity, multiferroicity, superconductivity, colossal magneto-resistance, magneto-electric coupling, etc. Epitaxial thin films of these materials are especially interesting for enhancement of fundamental understanding, in addition to development of potential device applications. High quality films are fabricated by pulsed laser deposition (PLD), magnetron sputtering, and thermal evaporation techniques. Especially, PLD is a versatile thin film growth technique, capable of growing almost any transition metal oxide material.

Dr. Kim's expertise in growing various complex metal oxide thin films and extensive characterization tools and techniques provides useful insights in designing nanostructure materials and/or devices. Four excellent graduate students have joined him for this exciting research and are establishing a state of the art complex-oxide thin film laboratory in Tulane University’s Uptown Campus. With the newly added oxide compatible research-cleanroom, they will investigate the following topics:

1. Develop novel thin film materials, which may lay a foundation for developing devices with advanced functionality;
2. Fabrication of nanostructured multiferroics for improved magneto-electric coupling;
3. Fabrication of various devices to characterize physical properties as well as to demonstrate novel functionality.

Top ⇑Low Temperature Condensed Matter Physics

Principal Investigator: Zhiqiang Mao

Tulane Group Members: Minghu Fang, Zhe Qu, David Fobes, Tijiang Liu, Jin Peng, Jin Hu

Group Website

Dr. Mao’s main research interest is in the area of strongly correlated materials. His long-term research goal is to seek for novel quantum phenomena in strongly correlated materials, investigate their underlying physics, and explore their applications. His current research focuses on perovskite ruthenates. Perovskite ruthenates exhibit a rich variety of fascinating ordered ground states, such as spin-triplet superconductivity, metamagnetic quantum criticality, itinerant ferromagnetism, antiferromagnetic Mott insulating state, and bad metal. The close proximity of these exotic states testifies to the delicate balance among the charge, spin, lattice and orbital degrees of freedom in ruthenates, and provides a remarkable opportunity for observing novel quantum phenomena through controlling external stimuli and for potential applications. Dr. Mao’s research work on ruthenates includes single-crystal growth and low-temperature measurements on electronic, magnetic, and thermal dynamic properties. He has also established important collaborations with National Labs to study microscopic magnetic properties of ruthenates via neutron scattering. In addition to ruthentes, Dr. Mao’s group is also studying magnetism and superconductivity of iron chalcogenides. The objective of this research subproject is to clarify the superconducting pairing symmetry as well as to shed light on the role of spin fluctuations in mediating Cooper pairing in this system.

Top ⇑Polymer Physics & Biophysics

Principal Investigator: Wayne Reed

Tulane Group Members: Alina Alb, Mike Drenski, Colin McFaul, Zheng Li, Zifu Zhu

Group Website

Research in my group centers on fundamental and applied aspects of Polymer Science, with an increasing emphasis on private sector liaison. We study biological and synthetic polymers in solution, with an aim towards discovering basic physical principals involved in their structures and interactions, as well as solving practical problems of immediate interest to such industries as pharmaceuticals, biotechnology, food, paints, adhesives, resins, coating, water purification, etc. To this end we are also strongly involved in developing new characterization techniques and instrumentation for polymers, especially those involving light scattering.

Efforts are concentrated on innovative ways of monitoring processes occurring in polymer solutions in real time. We make extensive use of light scattering and other optical techniques, viscometry, size exclusion chromatography, and other auxiliary techniques (DSC, electron-microscopy, etc.). We have interests in the fundamental areas of polymer reaction kinetics and mechanisms, conformations, interactions and hydrodynamics, with a special focus on polyelectrolytes.

Top ⇑Condensed Matter & Optical Spectroscopy

Principal Investigator: Diyar Talbayev

Tulane Group Members:Punam Silwal, Tianqi Shan

I am interested in optical and electronic properties of complex materials, which include materials with strong electronic correlations (e.g., magnetic and superconducting transition metal oxides), multiferroic materials that combine ferroelectricity with magnetism, and artificial nanoscale semiconductor structures. I use time-resolved optical and terahertz spectroscopy to probe low-energy magnetic, lattice, and electronic excitations that reveal the microscopic physics governing a material. Time-resolved spectroscopy employs femtosecond light pulses to perturb and manipulate the equilibrium state of solids and adds another dimension, the time domain, to expose the relationships between the fundamental interactions in a material.

Current research topics include:

1. Electronic properties and transport in mesoporous semiconductors and in artificial semiconductor nanostructures in the context of dye-sensitized solar cells.

2. Low energy excitations and time-resolved optical studies of magnetic ferroelectrics, aka multiferroics.

3. Quasiparticle dynamics in strongly correlated electron systems, specifically magnetic and superconducting materials.

Top ⇑Nanodevice Physics

Principal Investigator: Jiang Wei

Tulane Group Members: Chunlei Yue, Xue Liu, Jake Smith

Group Website

The Wei group's research interest focuses on nanoscale condensed matter physics, particularly on the underlying physics of the emerging quantum phenomena in nanostructures. Nanodevice physics fascinates us because when the characteristic length of physical systems approaches to nanoscale, quantum mechanical effects start to appear or even dominate. We are primarily interested in two groups of nanostructured materials: 1D and 2D quantum materials, and strongly correlated materials. We utilize our state-of-the-art micro-nano fabrication facilities to transform these materials into measureable nanoscale devices. Because low-dimensional material exhibits different physical properties from those of bulk material, we investigate the electrical, magnetic, and optical properties of low-dimensional structures to understand the fundamental physics. The nanostructured devices of strongly correlated material can be used as a research vehicle to explore the unknown territory of phase diagram, to investigate the collective many-body behavior, and to manipulate the phase transition by applying electric field, magnetic field, strain, and chemical doping. We also explore the technological applications of these nanodevices.

Current research directions:

• Quantum transport study of 1D and 2D materials
• Investigation of the phase transition on nanostructured strongly correlated materials modulated by mesoscopic strain and chemical doping engineering.
• Scanning photocurrent and surface enhanced Raman spectroscopy on nanodevices.
• Development of fabrication technique of ultra-small nanostructures.

Top ⇑Experimental Nuclear Physics

Principal Investigator: Fred Wietfeldt

Tulane Group Members: Alexander Laptev,Taufique Hassan, Chandra Shahi

My group is engaged in experimental nuclear physics research using cold and ultracold neutrons. This work falls into three related, but distinct categories:

1. Tests of the Electroweak Standard Model with precision measurements of neutron decay parameters
2. Studies of the hadronic weak interaction by measuring parity-violating parameters in neutron interactions with matter
3. Tests of nucleon forces and fundamental quantum mechanics using neutron interferometery.

   Our main focus right now is on categories (1) and (3).

Cold neutrons are free neutrons that are moving so slowly (less than 2000 m/s) that their deBroglie wavelengths are larger than the spacing between atoms in matter, typically in the range 0.2 to 2.0 nm. In this regime the neutron-matter interaction is coherent, the neutron interacts with many atoms simultaneously, and so it is more wave-like than particle-like. Cold neutrons can be manipulated optically, in many ways similar to light optics. They can be reflected, refracted, and diffracted in matter. Neutron guides, analogous to fiber optic guides, can be used to transport cold neutrons long distances with very little losses.

Ultracold neutrons (UCN's) are neutrons whose kinetic energy is less than about 300 neV. This energy is comparable to three important energy scales:

1. The neutron's optical potential in certain materials;
2. The neutron's potential energy in a strong magnetic field (~ 5 Tesla);
3. The neutron's gravitational potential energy at a height of several meters. Therefore UCN's can be trapped optically, magnetically, and gravitationally. A free neutron will decay into a proton, electron, and antineutrino with a lifetime of about 15 minutes. This is the simplest nuclear beta decay and the prototype semi-leptonic weak decay. The measurable parameters of neutron decay such as its lifetime and angular correlations can be directly related to fundamental parameters in the Electroweak Standard Model. Precision experiments can test the self-consistency of the theory and possibly point to new physics related to grand unification. In this way neutron decay plays an important role in the low-energy frontier of particle physics.

Precise measurements of neutron scattering lengths using a neutron interferometer can be used to improve our understanding of the nucleon-nucleon potential and other parameters such as the charge radius of the neutron. The neutron interferometer is also used for fundamental tests of quantum mechanics. These experiments are carried out at the National Institute of Standards and Technology (NIST) (Center for Neutron Research). In addition to comprehensive instrumentation for neutron scattering research, this facility supports and operates a suite of neutron beams (both monochromatic and polychromatic) dedicated to fundamental neutron physics. It also operates the most sensitive Neutron Interferometer in the world.

We design and develop experiments in our laboratories at Tulane, usually in collaboration with groups at other institutions, and then bring experiments to NIST for data collection. We usually spend summers at NIST and students in my group often spend one or more years full time at NIST, after completing their Tulane course-work, to complete their dissertation research.

Upcoming experiments:

• A measurement of the radiative decay branch of the neutron (never before observed)
• A precision measurement of the electron-antineutrino correlation (little "a") in neutron decay
• A precision measurement of the neutron-electron scattering length. This will lead to a determination of the charge radius of the neutron
• An improved measurement of the neutron scattering length in polarized 3He gas. This will provide important and unique information about nucleon-nucleon forces.
• A new measurement of gravitationally-induced quantum interference in a neutron interferometer. This tests the weak equivalence principle at the quantum limit.