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Publications

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

High-speed imaging at high x-ray energy: CdTe sensors coupled to charge-integrating pixel array detectors

Cornell Affiliated Author(s)
Author
J. Becker
M.W. Tate
K.S. Shanks
H.T. Philipp
J.T. Weiss
P. Purohit
Darol Chamberlain
Sol Gruner
Abstract

Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we describe the hybridization of CdTe sensors to two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory.

Conference Name
.
Date Published
Funding Source
DMR-1332208
DE-FG02-1 0ER46693
Group (Lab)
Sol M. Gruner Group

High-speed x-ray imaging with the Keck pixel array detector (Keck PAD) for time-resolved experiments at synchrotron sources

Cornell Affiliated Author(s)
Author
H.T. Philipp
M.W. Tate
P. Purohit
Darol Chamberlain
K.S. Shanks
J.T. Weiss
Sol Gruner
Abstract

Modern storage rings are readily capable of providing intense x-ray pulses, tens of picoseconds in duration, millions of times per second. Exploiting the temporal structure of these x-ray sources opens avenues for studying rapid structural changes in materials. Many processes (e.g. crack propagation, deformation on impact, turbulence, etc.) differ in detail from one sample trial to the next and would benefit from the ability to record successive x-ray images with single x-ray sensitivity while framing at 5 to 10 MHz rates.

Conference Name
x-ray imaging
Date Published
Group (Lab)
Sol M. Gruner Group

Potential beneficial effects of electron-hole plasmas created in silicon sensors by XFEL-like high intensity pulses for detector development

Cornell Affiliated Author(s)
Author
J.T. Weiss
J. Becker
K.S. Shanks
H.T. Philipp
M.W. Tate
Sol Gruner
Abstract

There is a compelling need for a high frame rate imaging detector with a wide dynamic range, from single x-rays/pixel/pulse to >106 x-rays/pixel/pulse, that is capable of operating at both x-ray free electron laser (XFEL) and 3rd generation sources with sustained fluxes of > 1011 x-rays/pixel/s [1, 2, 3].

Conference Name
.
Date Published
Funding Source
DMR-1332208
DE-FG02-1 0ER46693
Group (Lab)
Sol M. Gruner Group

The high dynamic range pixel array detector (HDR-PAD): Concept and design

Cornell Affiliated Author(s)
Author
K.S. Shanks
H.T. Philipp
J.T. Weiss
J. Becker
M.W. Tate
Sol Gruner
Abstract

Experiments at storage ring light sources as well as at next-generation light sources increasingly require detectors capable of high dynamic range operation, combining low-noise detection of single photons with large pixel well depth. XFEL sources in particular provide pulse intensities sufficiently high that a purely photon-counting approach is impractical.

Conference Name
.
Date Published
Group (Lab)
Sol M. Gruner Group

Structure of the Photo-catalytically Active Surface of SrTiO3

Cornell Affiliated Author(s)
Author
M. Plaza
X. Huang
J.Y.P. Ko
M. Shen
B.H. Simpson
J. Rodríguez-López
N.L. Ritzert
K. Letchworth-Weaver
D. Gunceler
D.G. Schlom
Tomas Arias
J.D. Brock
H.D. Abruña
Abstract

A major goal of energy research is to use visible light to cleave water directly, without an applied voltage, into hydrogen and oxygen. Although SrTiO3 requires ultraviolet light, after four decades, it is still the "gold standard" for the photo-catalytic splitting of water. It is chemically robust and can carry out both hydrogen and oxygen evolution reactions without an applied bias.

Journal
Journal of the American Chemical Society
Date Published
Funding Source
DMR-0936384
0936384
DE-SC0001086
Group (Lab)
Tomas Arias Group

Atomically Thin Ohmic Edge Contacts Between Two-Dimensional Materials

Cornell Affiliated Author(s)
Author
Marcos Guimarães
Hui Gao
Yimo Han
Kibum Kang
Saien Xie
Cheol-Joo Kim
David Muller
Daniel Ralph
Jiwoong Park
Abstract

With the decrease of the dimensions of electronic devices, the role played by electrical contacts is ever increasing, eventually coming to dominate the overall device volume and total resistance. This is especially problematic for monolayers of semiconducting transition-metal dichalcogenides (TMDs), which are promising candidates for atomically thin electronics. Ideal electrical contacts to them would require the use of similarly thin electrode materials while maintaining low contact resistances.

Journal
American Chemical Society (ACS)
Date Published
Funding Source
1406333
FA2386-13-1-4118
680-50-1311

Strong spin Hall effect in the antiferromagnet PtMn

Cornell Affiliated Author(s)
Author
Yongxi Ou
Shengjie Shi
D. Ralph
Robert Buhrman
Abstract

Effectively manipulating magnetism in ferromagnet (FM) thin-film nanostructures with an in-plane current has become feasible since the determination of a "giant" spin Hall effect (SHE) in certain heavy metal/FM systems. Recently, both theoretical and experimental reports indicate that metallic antiferromagnet materials can have both a large anomalous Hall effect and a strong SHE. Here we report a systematic study of the SHE in PtMn with several PtMn/FM systems.

Journal
American Physical Society (APS)
Date Published
Funding Source
DMR-1120296
ECCS-1542081