Exploratory Materials Synthesis & Characterization
Research
Our research program concentrates on the synthesis and
characterization of the new model materials of current interest in condensed
matter physics. We put strong effort in the discovery of new phenomena
associated with the correlated behavior of electrons, superconductivity and
magnetism. Most often materials are made in the single crystal form since
many observables of interest are tensor quantities and since this allows for
the investigation of properties that are free of grain boundaries influence.
New materials are prepared by variety of crystal growth and materials
synthesis methods: conventional arc melting and powder metallurgical
techniques, solution methods, high temperature intermetallic, oxide, sulfide
or salt fluxes, chemical vapor transport and deposition. Automated physical
and structural characterization is the essential component of the lab. In
order to optimize synthesis parameters, it is necessary to characterize
structural and physical properties of materials. Quite often the same
methods are used to probe and perturb crystal structure, transport,
thermodynamic and magnetic properties, sometimes at the extreme conditions.
Besides our lab instruments, we use environment of high magnetic fields and
low temperatures at NHMFL Tallahassee
and HZDR Dresden.
We also use NSLS EXAFS beamlines in
collaboration with
Anatoly Frenkel. There is considerable synergy and overlap with
BNL X-ray
scattering group. We are actively engaged in the
constant buildup of our synthesis and characterization capabilities by
custom designing and/or building of both materials synthesis and physical
characterization tools.
Our research portfolio consists of several general themes relevant to
Experimental Condensed Matter Physics (CMP) Core Research Area of the Office
of BES:
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1. Fe
based high-Tc superconductivity |
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We
pursue activities associated with studies of
the Fe based superconductors and related
materials within
Center for Emergent Superconductivity.
We focus on exploratory synthesis and
improvement of known iron selenide and iron
telluride superconductors. Exploratory
synthesis includes new materials design,
structure-property relations in similar
materials and search for crystal chemical
environment where superconductivity may
exist. Improvement of known materials
includes growth of crystals suitable for
particular experimental probes such as
neutron scattering or ARPES.
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2.
Quantum criticality |
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Heavy fermion superconductors with low
dimensional electronic systems and highly
anisotropic magnetic interactions offer a
model material for the study of
superconductivity near Quantum Critical
Point (QCP) in parameter space that is not
accessible in cuprate oxides (e.g.
above Hc2) or free from other
phenomena which may or may not be related to
superconductivity (e.g. disorder, charge
and/or magnetic ordering, etc..). We are
also exploring superconducting materials
near putative charge density wave (CDW) QCP
in low dimensional chalcogenide conductors. |
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3. Correlated electron
semiconductors |
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We
have an interest in exploring correlated
electron metallic states in materials where
there are no localized and well defined
4f moments and
where the large enhancement of the
quasiparticle mass is not related to
Abrikosov – Suhl resonance. Such materials
of interest are correlated electron
semiconductors with 3d
transition metal elements (FeSi – like) and
variety of other materials with residual and
frustrated magnetic interactions, charge
and/or orbital order. Prominent examples are
materials such as FeSi and FeSb2,
Kondo-insulator-like narrow band
semiconductors with large pileup of states
at the gap edges. Since the thermopower S is
very sensitive to variations in density of
states in the vicinity of the Fermi level,
very large values (|S|~100
µV/K) can be expected.
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4.
Dirac states in bulk
crystals |
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We
have embarked recently on the exploration of
Dirac states in bulk crystals. Quasi
two-dimensional electronic transport and
magnetotransport phenomena were observed in
single crystals of materials such as SrMnBi2
and CaMnBi2. The linear energy
dispersion in bulk bands leads to
nonsaturated linear magnetoresistance (MR)
since all Dirac fermions occupy the lowest
Landau level in the quantum limit. The
effective magnetoresistant mobility up to
μMR~3400 cm2/Vs is derived.
Angular-dependent magnetoresistance and
quantum oscillations suggest dominant 2D
Fermi surfaces. Our results imply that bulk
crystals with Bi square nets can be used to
study low-dimensional electronic transport
commonly found in 2D materials such as
graphene.
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Please forward all questions about this site to:
Cedomir Petrovic
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