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Publications

Detection of DNA and poly-l-lysine using CVD graphene-channel FET biosensors

Cornell Affiliated Author(s)
Author
A. Kakatkar
T.S. Abhilash
R. De Alba
J.M. Parpia
H.G. Craighead
Abstract

A graphene channel field-effect biosensor is demonstrated for detecting the binding of double-stranded DNA and poly-l-lysine. Sensors consist of chemical vapor deposition graphene transferred using a clean, etchant-free transfer method. The presence of DNA and poly-l-lysine are detected by the conductance change of the graphene transistor. A readily measured shift in the Dirac voltage (the voltage at which the graphene's resistance peaks) is observed after the graphene channel is exposed to solutions containing DNA or poly-l-lysine.

Journal
Nanotechnology
Date Published
Funding Source
DMR1202991
1202991
Group (Lab)
Jeevak Parpia Group

Avoided valence transition in a plutonium superconductor

Cornell Affiliated Author(s)
Author
B. Ramshaw
Arkady Shekhter
Ross McDonald
Jon Betts
J. Mitchell
P. Tobash
C. Mielke
E. Bauer
Albert Migliori
Abstract

The d and f electrons in correlated metals are often neither fully localized around their host nuclei nor fully itinerant. This localized/itinerant duality underlies the correlated electronic states of the high-Tc cuprate superconductors and the heavy-fermion intermetallics and is nowhere more apparent than in the 5f valence electrons of plutonium. Here, we report the full set of symmetry-resolved elastic moduli of PuCoGa5 - the highest Tc superconductor of the heavy fermions (Tc = 18.5 K) - and find that the bulk modulus softens anomalously over a wide range in temperature above Tc.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Funding Source
DMR-1157490
Group (Lab)
Brad Ramshaw Group

Higgs criticality in a two-dimensional metal

Cornell Affiliated Author(s)
Author
Debanjan Chowdhury
S. Sachdev
Abstract

We analyze a candidate theory for the strange metal near optimal hole doping in the cuprate superconductors. The theory contains a quantum phase transition between metals with large and small Fermi surfaces of spinless fermions carrying the electromagnetic charge of the electron, but the transition does not directly involve any broken global symmetries. The two metals have emergent SU(2) and U(1) gauge fields respectively, and the transition is driven by the condensation of a real Higgs field, carrying a finite lattice momentum and an adjoint SU(2) gauge charge.

Journal
Physical Review B - Condensed Matter and Materials Physics
Date Published
Funding Source
DMR-1360789
1360789
Group (Lab)
Debanjan Chowdhury Group

A high frame rate hybrid X-ray image sensor

Cornell Affiliated Author(s)
Author
A. Ercan
M.W. Tate
Sol Gruner
Abstract

This paper describes a solid-state image sensor for high-speed X-ray imaging. The sensor is made up of a light sensitive detector layer bump-bonded to a readout integrated circuit (ROIC). The detector layer is high resistivity n-type silicon and is fully depleted in operation. The p-implanted islands are used to define pixel regions with 100-μm × 100-μm area. The detector layer contains 852 × 209 pixels indium bump-bonded to four identical CMOS ROICs. Each ROIC contains 213 × 209 pixels and is fabricated using a 0.25-μm CMOS process.

Journal
IEEE Sensors Journal
Date Published
Funding Source
DE-FG-02978R62443
DE-FG-0297ER14805
DEFG02-10ER46693
Group (Lab)
Sol M. Gruner Group

Transverse collisional instabilities of a Bose-Einstein condensate in a driven one-dimensional lattice

Cornell Affiliated Author(s)
Author
S. Choudhury
E.J. Mueller
Abstract

Motivated by recent experiments, we analyze the stability of a three-dimensional Bose-Einstein condensate loaded in a periodically driven one-dimensional optical lattice. Such periodically driven systems do not have a thermodynamic ground state but may have a long-lived steady state which is an eigenstate of a "Floquet Hamiltonian." We explore collisional instabilities of the Floquet ground state which transfer energy into the transverse modes.

Journal
Physical Review A - Atomic, Molecular, and Optical Physics
Date Published

Evanescent-field optical readout of graphene mechanical motion at room temperature

Cornell Affiliated Author(s)
Author
R.M. Cole
G.A. Brawley
V.P. Adiga
R. De Alba
J.M. Parpia
B. Ilic
H.G. Craighead
W.P. Bowen
Abstract

Graphene mechanical resonators have recently attracted considerable attention for use in precision force- and mass-sensing applications. To date, readout of their oscillatory motion typically requires cryogenic conditions to achieve high sensitivity, restricting their range of applications. Here we report the demonstration of an evanescent optical readout of graphene motion, using a scheme which does not require cryogenic conditions and exhibits enhanced sensitivity and bandwidth at room temperature.

Journal
Physical Review Applied
Date Published
Funding Source
DMR 1120296
1202991
Group (Lab)
Jeevak Parpia Group

Spicing up continuum solvation models with SaLSA: The spherically averaged liquid susceptibility ansatz

Cornell Affiliated Author(s)
Author
R. Sundararaman
K.A. Schwarz
K. Letchworth-Weaver
Tomas Arias
Abstract

Continuum solvation models enable electronic structure calculations of systems in liquid environments, but because of the large number of empirical parameters, they are limited to the class of systems in their fit set (typically organic molecules). Here, we derive a solvation model with no empirical parameters for the dielectric response by taking the linear response limit of a classical density functional for molecular liquids.

Journal
Journal of Chemical Physics
Date Published
Group (Lab)
Tomas Arias Group

Imaging Dirac-mass disorder from magnetic dopant atoms in the ferromagnetic topological insulator Crx(Bi0.1Sb0.9)2-xTe3

Cornell Affiliated Author(s)
Author
I. Lee
C.K. Kim
J. Lee
S.J.L. Billinge
R. Zhong
J.A. Schneeloch
T. Liu
T. Valla
J.M. Tranquada
G. Gu
J.C.S. Davis
Abstract

To achieve and use the most exotic electronic phenomena predicted for the surface states of 3D topological insulators (TIs), it is necessary to open a "Dirac-mass gap" in their spectrum by breaking timereversal symmetry. Use of magnetic dopant atoms to generate a ferromagnetic state is the most widely applied approach. However, it is unknown how the spatial arrangements of the magnetic dopant atoms influence the Dirac-mass gap at the atomic scale or, conversely, whether the ferromagnetic interactions between dopant atoms are influenced by the topological surface states.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Group (Lab)
J.C. Seamus Davis Group

A microfabricated fixed path length silicon sample holder improves background subtraction for cryoSAXS

Cornell Affiliated Author(s)
Author
J.B. Hopkins
A.M. Katz
S.P. Meisburger
M.A. Warkentin
R.E. Thorne
L. Pollack
Abstract

The application of small-angle X-ray scattering (SAXS) for high-throughput characterization of biological macromolecules in solution is limited by radiation damage. By cryocooling samples, radiation damage and required sample volumes can be reduced by orders of magnitude. However, the challenges of reproducibly creating the identically sized vitrified samples necessary for conventional background subtraction limit the widespread adoption of this method. Fixed path length silicon sample holders for cryoSAXS have been microfabricated to address these challenges.

Journal
Journal of Applied Crystallography
Date Published
Research Area
Group (Lab)
Robert Thorne Group

Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors

Cornell Affiliated Author(s)
Author
M.P. Allan
K. Lee
A.W. Rost
M.H. Fischer
F. Massee
K. Kihou
C.-H. Lee
A. Iyo
H. Eisaki
T.-M. Chuang
J.C. Davis
Eun-Ah Kim
Abstract

Cooper pairing in the iron-based high-T c superconductors is often conjectured to involve bosonic fluctuations. Among the candidates are antiferromagnetic spin fluctuations and d-orbital fluctuations amplified by phonons. Any such electron-boson interaction should alter the electron's 'self-energy', and then become detectable through consequent modifications in the energy dependence of the electron's momentum and lifetime.

Journal
Nature Physics
Date Published
Funding Source
DE-SC0010313
DE-2009-BNL-PM015
DMR-0955822
DMR-1120296
0520404
22540380
EP/I031014/1
24340090
NSC101-2112-M-001-029-MY3
Group (Lab)
J.C. Seamus Davis Group