The field of Condensed Matter Physics and Materials Science integrates the knowledge and tools of chemistry and physics with the principles of engineering to understand and optimize the behavior of materials, as well as to create new and improved materials to help fulfill the missions of the Department of Energy.
Condensed-Matter Physics & Materials Science Seminar
"Berezinskii-Kosterlitz-Thouless-like transition in a highly underdoped La2-xSrxCuO4"
Presented by Dragana Popovic, NHMFL Tallahassee
1:30 pm, Bldg. 734, ISB Conf. Rm. 201 (upstairs)
Thursday, February 11, 2016, 1:30 pm
Hosted by: Cedomir Petrovic
In two-dimensional superconductors, the transition to the metallic state takes place via thermal unbinding of vortex-antivortex pairs, as described by the Berezinskii-Kosterlitz-Thouless (BKT) theory. The occurrence of the BKT transition in bulk underdoped samples of cuprate superconductors, which are highly anisotropic, layered materials, has been controversial. Therefore, the nature of the superconducting transition in highly underdoped thick films of La2-xSrxCuO4 has been investigated using the in-plane transport measurements. Both the temperature dependence of the paraconductivity above the transition and the nonlinear current-voltage (I-V) characteristics across it exhibit the main signatures of the BKT transition. Moreover, the quantitative comparison of the superfluid stiffness, extracted from the I-V data, with the renormalization-group results for the BKT theory, reveals a large value of the vortex-core energy, strongly suggesting that the relevant length scale controlling the BKT-like transition in this layered material involves a few coupled layers. Finally, measurements of the fluctuations of the resistance with time (i.e. noise) provide evidence for the critical slowing down of the dynamics and the onset of correlated behavior. The details of the observed dynamical critical behavior of the BKT transition and the role of disorder will be discussed.
Explores the electronic structure and electrodynamics of topological insulators and strongly correlated electron systems, with particular attention to emergent phenomena, such as superconductivity and magnetism, using angle-resolved photoemission (ARPES) and optical spectroscopy.
Studies the role of antiferromagnetism in high-temperature superconductors. The interaction of charge carriers with magnetic moments is of critical importance but remains a challenge to understand. .
Carries out basic studies of the structural, electronic and magnetic properties of condensed matter systems using synchrotron-based x-ray scattering techniques. .
Conducts basic research over a wide swath of theoretical physics, ranging from strongly correlated electrons to first principle electronic structure theory.
Studies both the microscopic and macroscopic properties of complex and nano-structured materials with a view to understanding and developing their application in different energy related technologies
Addresses key open questions in HTS physics such as the dimensionality of the HTS phenomenon, the spin and charge of free carriers, the nature of the superconducting transition, the role of charge stripes (if any) in the HTS state, the nature of the overdoped metallic state, and more.
Span a wide range of quantum matter systems, including superconductors, superfluids, supersolids, electronic liquid crystals, topological insulators superconductors & superfluids, heavy fermions, and spin liquids. Throughout, the focus is on development of innovative techniques and approaches to each problem.
Utilizes advanced electron microscopy techniques to study nanoscale structure and defects that determine the utility of functional materials, such as superconductors, multiferroics, and other energy related systems including thermoelectrics, photovoltaics, and batteries.
The Condensed Matter Physics and Materials Science Department is part of Brookhaven National Laboratory's Energy Sciences Directorate.