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Publications

Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

Cornell Affiliated Author(s)
Author
A. Munke
J. Andreasson
A. Aquila
S. Awel
K. Ayyer
A. Barty
R.J. Bean
P. Berntsen
J. Bielecki
S. Boutet
M. Bucher
H.N. Chapman
B.J. Daurer
H. Demirci
V. Elser
P. Fromme
J. Hajdu
M.F. Hantke
A. Higashiura
B.G. Hogue
A. Hosseinizadeh
Y. Kim
R.A. Kirian
H.K.N. Reddy
T.-Y. Lan
D.S.D. Larsson
H. Liu
N.D. Loh
F.R.N.C. Maia
A.P. Mancuso
K. Mühlig
A. Nakagawa
D. Nam
G. Nelson
C. Nettelblad
K. Okamoto
A. Ourmazd
M. Rose
G. Van Der Schot
P. Schwander
M.M. Seibert
J.A. Sellberg
R.G. Sierra
C. Song
M. Svenda
N. Timneanu
I.A. Vartanyants
D. Westphal
M.O. Wiedorn
G.J. Williams
P.L. Xavier
C.H. Yoon
J. Zook
Abstract

Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded.

Journal
Scientific Data
Date Published
Funding Source
R01GM097463
Group (Lab)
Veit Elser Group

Dragonfly: An implementation of the expand-maximize-compress algorithm for single-particle imaging

Cornell Affiliated Author(s)
Author
K. Ayyer
T.-Y. Lan
V. Elser
N.D. Loh
Abstract

Single-particle imaging (SPI) with X-ray free-electron lasers has the potential to change fundamentally how biomacromolecules are imaged. The structure would be derived from millions of diffraction patterns, each from a different copy of the macromolecule before it is torn apart by radiation damage. The challenges posed by the resultant data stream are staggering: millions of incomplete, noisy and un-oriented patterns have to be computationally assembled into a three-dimensional intensity map and then phase reconstructed.

Journal
Journal of Applied Crystallography
Date Published
Group (Lab)
Veit Elser Group

Gender gaps and gendered action in a first-year physics laboratory

Cornell Affiliated Author(s)
Author
J. Day
J.B. Stang
N.G. Holmes
D. Kumar
D.A. Bonn
Abstract

It is established that male students outperform female students on almost all commonly used physics concept inventories. However, there is significant variation in the factors that contribute to the gap, as well as the direction in which they influence it. It is presently unknown if such a gender gap exists on the relatively new Concise Data Processing Assessment (CDPA) and, therefore, whether gendered actions in the teaching lab might influence - or be influenced by - the gender gap.

Journal
Physical Review Physics Education Research
Date Published

Single reconstructed Fermi surface pocket in an underdoped single-layer cuprate superconductor

Cornell Affiliated Author(s)
Author
M. Chan
N. Harrison
R. McDonald
B. Ramshaw
K. Modic
N. Barišc
M. Greven
Abstract

The observation of a reconstructed Fermi surface via quantum oscillations in hole-doped cuprates opened a path towards identifying broken symmetry states in the pseudogap regime. However, such an identification has remained inconclusive due to the multi-frequency quantum oscillation spectra and complications accounting for bilayer effects in most studies. We overcome these impediments with high-resolution measurements on the structurally simpler cuprate HgBa2CuO4+δ (Hg1201), which features one CuO2 plane per primitive unit cell.

Journal
Nature Communications
Date Published
Funding Source
1157490
Group (Lab)
Brad Ramshaw Group

Epitaxial growth and electronic properties of mixed valence YbAl3 thin films

Cornell Affiliated Author(s)
Author
S. Chatterjee
S.H. Sung
D.J. Baek
L.F. Kourkoutis
D.G. Schlom
K.M. Shen
Abstract

We report the growth of thin films of the mixed valence compound YbAl3 on MgO using molecular-beam epitaxy. Employing an aluminum buffer layer, epitaxial (001) films can be grown with sub-nm surface roughness. Using x-ray diffraction, in situ low-energy electron diffraction, and aberration-corrected scanning transmission electron microscopy, we establish that the films are ordered in the bulk as well as at the surface. Our films show a coherence temperature of 37 K, comparable to that reported for bulk single crystals.

Journal
Journal of Applied Physics
Date Published
Funding Source
0847385
1120296
1429155
Group (Lab)
Kyle Shen Group

Manipulating superconductivity in ruthenates through Fermi surface engineering

Cornell Affiliated Author(s)
Author
Y.-T. Hsu
W. Cho
A.F. Rebola
B. Burganov
C. Adamo
K.M. Shen
D.G. Schlom
C.J. Fennie
Eun-Ah Kim
Abstract

The key challenge in superconductivity research is to go beyond the historical mode of discovery-driven research. We put forth a new strategy, which is to combine theoretical developments in the weak-coupling renormalization-group approach with the experimental developments in lattice-strain-driven Fermi surface engineering. For concreteness we theoretically investigate how superconducting tendencies will be affected by strain engineering of ruthenates' Fermi surface. We first demonstrate that our approach qualitatively reproduces recent experiments under uniaxial strain.

Journal
Physical Review B
Date Published
Group (Lab)
Kyle Shen Group

Examining and contrasting the cognitive activities engaged in undergraduate research experiences and lab courses

Cornell Affiliated Author(s)
Author
N.G. Holmes
C.E. Wieman
Abstract

While the positive outcomes of undergraduate research experiences (UREs) have been extensively categorized, the mechanisms for those outcomes are less understood. Through lightly structured focus group interviews, we have extracted the cognitive tasks that students identify as engaging in during their UREs. We also use their many comparative statements about their coursework, especially lab courses, to evaluate their experimental physics-related cognitive tasks in those environments.

Journal
Physical Review Physics Education Research
Date Published

Cold-spots and glassy nematicity in underdoped cuprates

Cornell Affiliated Author(s)
Author
K. Lee
S.A. Kivelson
Eun-Ah Kim
Abstract

There is now copious direct experimental evidence of various forms of (short-range) charge order in underdoped cuprate high temperature superconductors, and spectroscopic signatures of a nodal-antinodal dichotomy in the structure of the single-particle spectral functions. In this context we analyze the Bogoliubov quasiparticle spectrum in a superconducting nematic glass.

Journal
Physical Review B
Date Published
Group (Lab)

Mie Resonance-Modulated Spatial Distributions of Photogenerated Carriers in Poly(3-hexylthiophene-2,5-diyl)/Silicon Nanopillars

Cornell Affiliated Author(s)
Author
Eun-Ah Kim
Y. Cho
A. Sohn
H. Hwang
Y.U. Lee
K. Kim
H.-H. Park
J. Kim
J.W. Wu
D.-W. Kim
Abstract

Organic/silicon hybrid solar cells have great potential as low-cost, high-efficiency photovoltaic devices. The superior light trapping capability, mediated by the optical resonances, of the organic/silicon hybrid nanostructure-based cells enhances their optical performance. In this work, we fabricated Si nanopillar (NP) arrays coated with organic semiconductor, poly(3-hexylthiophene-2,5-diyl), layers. Experimental and calculated optical properties of the samples showed that Mie-resonance strongly concentrated incoming light in the NPs.

Journal
Scientific Reports
Date Published
Group (Lab)

A network that learns Strassen multiplication

Cornell Affiliated Author(s)
Author
V. Elser
Abstract

We study neural networks whose only non-linear components are multipliers, to test a new training rule in a context where the precise representation of data is paramount. These networks are challenged to discover the rules of matrix multiplication, given many examples. By limiting the number of multipliers, the network is forced to discover the Strassen multiplication rules. This is the mathematical equivalent of finding low rank decompositions of the n x n matrix multiplication tensor, Mn.

Journal
Journal of Machine Learning Research
Date Published
Group (Lab)
Veit Elser Group