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Publications

Scatterometry measurement for gate ADI and AEI CD of 28nm metal gates

Cornell Affiliated Author(s)
Author
Y.H. Huang
C.H. Chen
K. Shen
H.H. Chen
C.C. Yu
J.H. Liao
Abstract

For reduced gate leakage and enhanced device performance, many IC manufacturers utilize novel metal gate technologies instead of traditional poly silicon gates. The new materials and geometries required to form metal gates mean that new parameters control the optimization of device performance [1]. Traditional gate process control has relied heavily on scatterometry for ensuring that variation in structural dimensions remain in control, as some dimensional deviations can strongly affect device performance.

Journal
Solid State Technology
Date Published
Group (Lab)
Kyle Shen Group

Topological defects coupling smectic modulations to intra-unit-cell nematicity in cuprates

Cornell Affiliated Author(s)
Author
A. Mesaros
K. Fujita
H. Eisaki
S. Uchida
J.C. Davis
S. Sachdev
J. Zaanen
M.J. Lawler
Eun-Ah Kim
Abstract

We study the coexisting smectic modulations and intra-unit-cell nematicity in the pseudogap states of underdoped Bi 2Sr 2CaCu 2O 8+δ. By visualizing their spatial components separately, we identified 2π topological defects throughout the phase-fluctuating smectic states. Imaging the locations of large numbers of these topological defects simultaneously with the fluctuations in the intra-unit-cell nematicity revealed strong empirical evidence for a coupling between them.

Journal
Science
Date Published
Group (Lab)
J.C. Seamus Davis Group
Michael Lawler Group

Nernst effect in the cuprate superconductor YBa2Cu 3Oy: Broken rotational and translational symmetries

Cornell Affiliated Author(s)
Author
J. Chang
Nicolas Doiron-Leyraud
Francis Laliberté
R. Daou
David LeBoeuf
B. Ramshaw
Ruixing Liang
D. Bonn
W. Hardy
Cyril Proust
I. Sheikin
K. Behnia
Louis Taillefer
Abstract

The Nernst coefficient of the cuprate superconductor YBa2Cu 3Oy was recently shown to become strongly anisotropic within the basal plane when cooled below the pseudogap temperature T, revealing that the pseudogap phase breaks the fourfold rotational symmetry of the CuO 2 planes. Here we report on the evolution of this Nernst anisotropy at low temperature, once superconductivity is suppressed by a magnetic field. We find that the anisotropy drops rapidly below 80 K, to vanish in the T=0 limit.

Journal
Physical Review B - Condensed Matter and Materials Physics
Date Published
Group (Lab)
Brad Ramshaw Group

Techniques to measure quantum criticality in cold atoms

Cornell Affiliated Author(s)
Author
K.R.A. Hazzard
E.J. Mueller
Abstract

We describe how rescaling experimental data obtained from cold atom density profiles can reveal signatures of quantum criticality. We identify a number of important questions which can be answered by analyzing experimental data in this manner. We show that such experiments can distinguish different universality classes and that the signatures are robust against temperature, noise, and finite system size. © 2011 American Physical Society.

Journal
Physical Review A - Atomic, Molecular, and Optical Physics
Date Published
Funding Source
0758104

An in-vacuum diffractometer for resonant elastic soft x-ray scattering

Cornell Affiliated Author(s)
Author
D.G. Hawthorn
F. He
L. Venema
H. Davis
A.J. Achkar
J. Zhang
R. Sutarto
H. Wadati
A. Radi
T. Wilson
G. Wright
K.M. Shen
J. Geck
H. Zhang
V. Novák
G.A. Sawatzky
Abstract

We describe the design, construction, and performance of a 4-circle in-vacuum diffractometer for resonant elastic soft x-ray scattering. The diffractometer, installed on the resonant elastic and inelastic x-ray scattering beamline at the Canadian Light Source, includes 9 in-vacuum motions driven by in-vacuum stepper motors and operates in ultra-high vacuum at base pressure of 2 × 10-10 Torr. Cooling to a base temperature of 18 K is provided with a closed-cycle cryostat.

Journal
Review of Scientific Instruments
Date Published
Group (Lab)
Kyle Shen Group

Development of high-performance X-ray transparent crystallization plates for in situ protein crystal screening and analysis

Cornell Affiliated Author(s)
Author
A.S.M. Soliman
M. Warkentin
B. Apker
R.E. Thorne
Abstract

X-ray transparent crystallization plates based upon a novel drop-pinning technology provide a flexible, simple and inexpensive approach to protein crystallization and screening. The plates consist of open cells sealed top and bottom by thin optically, UV and X-ray transparent films. The plates do not need wells or depressions to contain liquids. Instead, protein drops and reservoir solution are held in place by rings with micrometre dimensions that are patterned onto the bottom film.

Journal
Acta Crystallographica Section D: Biological Crystallography
Date Published
Research Area
Group (Lab)
Robert Thorne Group

Direct measurements of torque during holliday junction migration

Cornell Affiliated Author(s)
Author
S. Forth
C. Deufel
S.S. Patel
M.D. Wang
Abstract

DNA experiences torsional stress resulting from the activities of motor enzymes and bound proteins. The mechanisms by which this torsional stress is dissipated to maintain DNA structural integrity are not fully known. Here, we show that a Holliday junction can limit torsion by coupling rotation to translocation and torque to force. The torque required to mechanically migrate through individual junctions was found to be an order of magnitude smaller than that required to melt DNA.

Journal
Biophysical Journal
Date Published
Research Area
Group (Lab)
Michelle Wang Group

Electronic structure of the cuprate superconducting and pseudogap phases from spectroscopic imaging STM

Cornell Affiliated Author(s)
Author
A.R. Schmidt
K. Fujita
Eun-Ah Kim
M.J. Lawler
H. Eisaki
S. Uchida
D.-H. Lee
J.C. Davis
Abstract

We survey the use of spectroscopic imaging scanning tunneling microscopy (SI-STM) to probe the electronic structure of underdoped cuprates. Two distinct classes of electronic states are observed in both the d-wave superconducting (dSC) and the pseudogap (PG) phases. The first class consists of the dispersive Bogoliubov quasiparticle excitations of a homogeneous d-wave superconductor, existing below a lower energy scale E = Δ0.

Journal
New Journal of Physics
Date Published
Group (Lab)
J.C. Seamus Davis Group
Michael Lawler Group

High-pressure protein crystallography and NMR to explore protein conformations

Cornell Affiliated Author(s)
Author
M.D. Collins
C.U. Kim
Sol Gruner
Abstract

High-pressure methods for solving protein structures by X-ray crystallography and NMR are maturing. These techniques are beginning to impact our understanding of thermodynamic and structural features that define not only the protein's native conformation, but also the higher free energy conformations. The ability of high-pressure methods to visualize these mostly unexplored conformations provides new insight into protein function and dynamics.

Journal
Annual Review of Biophysics
Date Published
Research Area
Group (Lab)
Sol M. Gruner Group