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Publications

ZrNb(CO) RF Superconducting Thin Film with High Critical Temperature in the Theoretical Limit

Cornell Affiliated Author(s)
Author
Z. Sun
T. Oseroff
Z. Baraissov
D.K. Dare
K. Howard
B. Francis
A.C. Hire
N. Sitaraman
T.A. Arias
M.K. Transtrum
R. Hennig
M.O. Thompson
D.A. Muller
M.U. Liepe
Abstract

Superconducting radio-frequency (SRF) resonators are critical components for particle accelerator applications, such as free-electron lasers, and for emerging technologies in quantum computing. Developing advanced materials and their deposition processes to produce RF superconductors that yield nΩ surface resistances is a key metric for the wider adoption of SRF technology. Here, ZrNb(CO) RF superconducting films with high critical temperatures (Tc) achieved for the first time under ambient pressure are reported.

Journal
Advanced Electronic Materials
Date Published
Funding Source
NNCI‐2025233
PHY‐1549132
DMR‐1719875
Group (Lab)
Tomas Arias Group

Pulsing the Applied Potential in Electrochemical CO2 Reduction Enhances the C2 Activity by Modulating the Dynamic Competitive Binding of *CO and *H

Cornell Affiliated Author(s)
Author
Casebolt DiDomenico
K. Levine
C. Bundschu
L. Reimanis
T. Arias
T. Hanrath
Abstract

We explore dynamic electrocatalysis by pulsing the applied potential to modulate the temporal microenvironment during the electrochemical reduction of CO2. We focus on copper electrodes by virtue of their unique ability to bind *CO intermediates and enable C-C coupling to form high-value C2 products, such as ethylene or ethanol. We examine the well-known competition between *CO and *H for active sites, as their relative coverage is crucial for enhancing the formation of C2 products.

Journal
ACS Catalysis
Date Published
Funding Source
CBET1805400
CHE-1531632
Group (Lab)
Tomas Arias Group

Fully Ab Initio Approach to Inelastic Atom-Surface Scattering

Cornell Affiliated Author(s)
Author
M.M. Kelley
R. Sundararaman
T.A. Arias
Abstract

We introduce a fully ab initio theory for inelastic scattering of any atom from any surface exciting single phonons, and apply the theory to helium scattering from Nb(100). The key aspect making our approach general is a direct first-principles evaluation of the scattering atom-electron vertex. By correcting misleading results from current state-of-the-art theories, this fully ab initio approach will be critical in guiding and interpreting experiments that adopt next-generation, nondestructive atomic beam scattering. © 2024 American Physical Society.

Journal
Physical Review Letters
Date Published
Group (Lab)
Tomas Arias Group

Atomically smooth films of CsSb: A chemically robust visible light photocathode

Author
C.T. Parzyck
C.A. Pennington
W.J.I. Debenedetti
J. Balajka
E.M. Echeverria
H. Paik
L. Moreschini
B.D. Faeth
C. Hu
J.K. Nangoi
V. Anil
T.A. Arias
M.A. Hines
D.G. Schlom
A. Galdi
K.M. Shen
J.M. Maxson
Abstract

Alkali antimonide semiconductor photocathodes provide a promising platform for the generation of high-brightness electron beams, which are necessary for the development of cutting-edge probes, including x-ray free electron lasers and ultrafast electron diffraction. Nonetheless, to harness the intrinsic brightness limits in these compounds, extrinsic degrading factors, including surface roughness and contamination, must be overcome.

Journal
APL Materials
Date Published
Funding Source
DMR-2039380
DMR-2104427
PHY-1549132
DE-AC02-76SF00515
DE-SC0020144
DMR-1719875
NNCI-2025233
OAC 1920103
FA9550-21-1-0168
Group (Lab)
Kyle Shen Group
Tomas Arias Group

Theory of photoemission from cathodes with disordered surfaces

Cornell Affiliated Author(s)
Author
P. Saha
O. Chubenko
Kevin Nangoi
Tomas Arias
E. Montgomery
S. Poddar
H.A. Padmore
S. Karkare
Abstract

Linear-accelerator-based applications like x-ray free electron lasers, ultrafast electron diffraction, electron beam cooling, and energy recovery linacs use photoemission-based cathodes in photoinjectors for electron sources. Most of these photocathodes are typically grown as polycrystalline materials with disordered surfaces. In order to understand the mechanism of photoemission from such cathodes and completely exploit their photoemissive properties, it is important to develop a photoemission formalism that properly describes the subtleties of these cathodes.

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

Material normal energy distribution for field emission analyses from monocrystalline surfaces

Cornell Affiliated Author(s)
Author
J.I. Mann
Y. Li
J.K. Nangoi
Tomas Arias
J.B. Rosenzweig
Abstract

Electron field emission is a complicated phenomenon which is sensitive not only to the particular material under illumination but also to the specific crystalline orientation of the surface. Summarizing the ability for a crystal to emit in a particular direction would be of great use when searching for good field emitters. In this paper we propose a material normal energy distribution which describes the ability of the bound electrons to tunnel under an intense electric field.

Conference Name
Journal of Physics Conference Series
Date Published
Funding Source
PHY-1549132
Group (Lab)
Tomas Arias Group

Dissipation by surface states in superconducting radio-frequency cavities

Author
S. Deyo
M. Kelley
N. Sitaraman
T. Oseroff
D.B. Liarte
Tomas Arias
M. Liepe
J.P. Sethna
Abstract

Recent experiments on superconducting cavities have found that under large rf electromagnetic fields the quality factor can improve with increasing field amplitude, a so-called "anti-Q slope."Linear theories of dissipation break down under these extreme conditions and are unable to explain this behavior. We numerically solve the Bogoliubov-de Gennes equations at the surface of a superconductor in a parallel AC magnetic field, finding that at large fields there are quasiparticle surface states with energies below the bulk value of the superconducting gap.

Journal
Physical Review B
Date Published
Group (Lab)
James Sethna Group
Tomas Arias Group

A combined helium atom scattering and density-functional theory study of the Nb(100) surface oxide reconstruction: Phonon band structures and vibrational dynamics

Cornell Affiliated Author(s)
Author
A.A. McMillan
C.J. Thompson
M.M. Kelley
J.D. Graham
Tomas Arias
S.J. Sibener
Abstract

Helium atom scattering and density-functional theory (DFT) are used to characterize the phonon band structure of the (3 × 1)-O surface reconstruction of Nb(100). Innovative DFT calculations comparing surface phonons of bare Nb(100) to those of the oxide surface show increased resonances for the oxide, especially at higher energies. Calculated dispersion curves align well with experimental results and yield atomic displacements to characterize polarizations.

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

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Cornell Affiliated Author(s)
Author
Y. Yang
C.R. Peltier
R. Zeng
R. Schimmenti
Q. Li
X. Huang
Z. Yan
G. Potsi
R. Selhorst
X. Lu
W. Xu
M. Tader
A.V. Soudackov
H. Zhang
M. Krumov
E. Murray
P. Xu
J. Hitt
L. Xu
H.-Y. Ko
B.G. Ernst
C. Bundschu
A. Luo
D. Markovich
M. Hu
C. He
H. Wang
J. Fang
R.A. Distasio
L.F. Kourkoutis
A. Singer
K.J.T. Noonan
L. Xiao
L. Zhuang
B.S. Pivovar
P. Zelenay
E. Herrero
J.M. Feliu
J. Suntivich
E.P. Giannelis
S. Hammes-Schiffer
Tomas Arias
M. Mavrikakis
T.E. Mallouk
J.D. Brock
D.A. Muller
F.J. DiSalvo
G.W. Coates
H.D. Abruña
Abstract

Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers.

Journal
Chemical Reviews
Date Published
Group (Lab)
Tomas Arias Group

Single-Crystal Alkali Antimonide Photocathodes: High Efficiency in the Ultrathin Limit

Cornell Affiliated Author(s)
Author
C.T. Parzyck
A. Galdi
J.K. Nangoi
W.J.I. Debenedetti
J. Balajka
B.D. Faeth
H. Paik
C. Hu
Tomas Arias
M.A. Hines
D.G. Schlom
K.M. Shen
J.M. Maxson
Abstract

The properties of photoemission electron sources determine the ultimate performance of a wide class of electron accelerators and photon detectors. To date, all high-efficiency visible-light photocathode materials are either polycrystalline or exhibit intrinsic surface disorder, both of which limit emitted electron beam brightness. In this Letter, we demonstrate the synthesis of epitaxial thin films of Cs3Sb on 3C-SiC (001) using molecular-beam epitaxy. Films as thin as 4 nm have quantum efficiencies exceeding 2% at 532 nm.

Journal
Physical Review Letters
Date Published
Group (Lab)
Kyle Shen Group
Tomas Arias Group