When a large number of atoms condense into a fluid or solid, behaviors emerge that are only indirectly related to the physics of the individual atoms. Superconductivity is one such an emergent behavior, which could not be anticipated from even a detailed study of an isolated atom. The goal of condensed matter physics is not only to measure and explain such emergent phenomena, but also to manipulate these properties to produce the novel effects we desire. This allows us to both investigate fundamental physics and to develop commercially important applications.
A student in condensed matter physics must have a thorough understanding of both the microscopic quantum mechanics that underlies the system and the classical macroscopic theories of mechanics, electromagnetism, and statistical mechanics that describe its large scale behavior. This broad background enables students to go on to careers in academia, government labs, and industry.
The condensed matter group encompasses semiconductor physics, soft-matter physics, and nanophysics. A major focus of our group is the experimental and theoretical study of highly confined electron systems in artificially structured semiconductors and other low dimensional materials.
|Trenches etched by Prof. Johnson in GaAs using an Ar+ beam with an anodized aluminum oxide (AAO) mask. Note this technique can be done remotely in vacuo, thus it is fully compatible with MBE. This is an example of a "top-down" fabrication method.|
|A flat gold nanoparticle grown by Prof. Bumm in solution, imaged by an electron microscope. The symmetric structure of the particle arises spontaneously from the local surface energies during growth. This is an example of a "bottom-up" method.|
The majority of our experimental research takes place in the department's state-of-the-art laboratories.
Our well equipped facilities include: a dual-chamber molecular beam epitaxy (MBE) system for the growth of III-V and IV-VI semiconductors; several scanning tunneling and atomic force microscopes for high resolution imaging and patterning of atomic surfaces; a cleanroom for optical lithography and semiconductor processing; a thin-film laboratory for routine vapor deposition; low temperature (<20 mK) and high magnetic field (15 T) facilities for optical and electrical studies; optical microscopes for single nanoparticle spectroscopy; a grazing angle infrared spectrometer for molecular spectroscopy of monolayers; full characterization techniques for solar cells analysis including a class-A solar simulator, an external quantum efficiency system with capacitance-voltage analysis equipment; and picosecond pulsed laser systems for our polymer studies. Scanning electron and transmission electron microscopes are available in the Samuel Roberts Noble Electron Microscopy Laboratory and are routinely used by our students for their research.
The condensed matter theory group is interested in many areas of research including new quantum phases in strongly correlated systems, quantum criticality and transport in semiconductor and carbon nanoscale systems.
New quantum phases include such diverse examples as chiral edge states in topological insulators, novel superconducting condensates in carbon-based systems, and polarized arrays of quantum rings. Quantum criticality refers to phase transitions driven by quantum fluctuations rather than temperature, such as those in Dirac materials like graphene, high temperature superconductors and possibly transition metal dichalcogenides. The group's transport studies involve currents in heat, charge, energy, spin and pseudo-spin in mesoscopic systems in general. In addition theory is an important partner to the above experimental efforts.
The faculty in condensed matter physics share appointments in the engineering physics program. The engineering physicist provides the link between the pure scientist and the engineer by applying fundamental scientific theories to the solution of technological problems. As the miniaturization of transistors, lasers, and memory elements continues, an understanding of their operation increasingly requires knowledge of the underlying physics.