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Scientists in Brookhaven's Condensed Matter Physics & Materials Science Department study basic, theoretical and applied aspects of materials, their utilization, and their electronic, physical, mechanical, and chemical properties in relation to their structure. 

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.

  1. DEC

    21

    Thursday

    Condensed-Matter Physics & Materials Science Seminar

    "Spin fluctuations in 122 transition metal arsenides measured using inelastic neutron scattering technique"

    Presented by Aashish Sapkota, Ames Laboratory

    1:30 pm, ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Thursday, December 21, 2017, 1:30 pm

    Hosted by: '''John Tranquada'''

    122 transition metal compounds with ThCr2Si2-type structure have been extensively studied because of their wide range of interesting physical properties like superconductivity, valence fluctuations, various magnetic ground states, etc. A subset (ATM2Pn2) of this class consisting of alkaline earth metals (A), 3d transition metals (TM) and pnictogen (Pn) attracted significant interest after discovery of an unconventional superconductivity in 122 iron arsenide compounds. In 122 iron arsenide superconductors, magnetism is in close proximity to the superconductivity and the spin fluctuations are considered as a key component for the pairing mechanism for superconductivity. These properties as well as the wide range of magnetic ground states, found in ATM2As2, motivated a detail studies of the magnetism in these compounds and neutron scattering technique has been extensively used for the study. In this seminar, I will discuss our results of inelastic neutron scattering measurements of the spin fluctuations in two compounds [CaCo1.86As2 and Ca(Fe1-xCox)2As2] of ATM2Pn2 class. First, I will discuss extremely extended spin fluctuations along two directions of reciprocal space in CaCo1.86As2, which shows A-type antiferromagnetic ground states. The result suggests that CaCo1.86As2 is highly-frustrated and is a unique example of highly-frustrated square-lattice system. Next, I will discuss the evolution of the spin fluctuations in Co-doped CaFe2As2 and compare it to that of Co-doped BaFe2As2. In this part, I will also discuss a peculiar suppression of the spin fluctuations with temperature observed in Ca(Fe1-xCox)2As2, x = 0.030 compound, which shows superconducting ground state.

Electron Spectroscopy

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.

Neutron Scattering

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. .

X-Ray Scattering

Carries out basic studies of the structural, electronic and magnetic properties of condensed matter systems using synchrotron-based x-ray scattering techniques. .

Condensed Matter Theory

Conducts basic research over a wide swath of theoretical physics, ranging from strongly correlated electrons to first principle electronic structure theory.  

Advanced Energy Materials

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

Oxide Molecular Beam Epitaxy

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.

Spectroscopic Imaging

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.

Electron Microscopy and Nanostructure

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.