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Publications

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
Funding Source
NSF-DMR-2011854
PHY-1549132
FA9550-19-1-0324
Group (Lab)
Tomas Arias Group

Origin of transverse voltages generated by thermal gradients and electric fields in ferrimagnetic-insulator/heavy-metal bilayers

Cornell Affiliated Author(s)
Author
Arnab Bose
Rakshit Jain
Jackson Bauer
Robert Buhrman
Caroline Ross
Daniel Ralph
Abstract

We compare thermal-gradient-driven transverse voltages in ferrimagnetic-insulator/heavy-metal bilayers (Tm3Fe5O12/W and Tm3Fe5O12/Pt) to corresponding electrically driven transverse resistances at and above room temperature. We find for Tm3Fe5O12/W that the thermal and electrical effects can be explained by a common spin-current detection mechanism, the physics underlying spin Hall magnetoresistance (SMR).

Journal
American Physical Society (APS)
Date Published
Funding Source
DMR-1719875
DE-SC0017671
DMR-1808190
NNCI-2025233
DMR-1419807

Comparing Thickness and Doping-Induced Effects on the Normal States of Infinite-Layer Electron-Doped Cuprates: Is There Anything to Learn?

Cornell Affiliated Author(s)
Author
C. Sacco
A. Galdi
F. Romeo
N. Coppola
P. Orgiani
H.I. Wei
K.M. Shen
D.G. Schlom
L. Maritato
Abstract

We grew Sr1−xLaxCuO2 thin films and SrCuO2/Sr0.9La0.1CuO2/SrCuO2 trilayers by reflection high-energy diffraction-calibrated layer-by-layer molecular beam epitaxy, to study their electrical transport properties as a function of the doping and thickness of the central Sr0.9La0.1CuO2 layer.

Journal
Nanomaterials
Date Published
Group (Lab)
Kyle Shen Group

Strong interlayer interactions in bilayer and trilayer moire superlattices

Author
S. Xie
B.D. Faeth
Y. Tang
L. Li
E. Gerber
C.T. Parzyck
Debanjan Chowdhury
Y.-H. Zhang
C. Jozwiak
A. Bostwick
E. Rotenberg
Eun-Ah Kim
J. Shan
K.F. Mak
K.M. Shen
Abstract

Moire superlattices constructed from transition metal dichalcogenides have demonstrated a series of emergent phenomena, including moire excitons, flat bands, and correlated insulating states. All of these phenomena depend crucially on the presence of strong moire potentials, yet the properties of these moire potentials, and the mechanisms by which they can be generated, remain largely open questions. Here, we use angle-resolved photoemission spectroscopy with submicron spatial resolution to investigate an aligned WS2/WSe2moire superlattice and graphene/WS2/WSe2trilayer heterostructure.

Journal
Science Advances
Date Published
Group (Lab)
Debanjan Chowdhury Group
Jie Shan Group
Kin Fai Mak Group
Kyle Shen 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
Funding Source
DMR1719875
DMR-1332208
DE-SC0019445
R01CA245134
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
Funding Source
DMR-2039380
PHY-1549132
DMR-1719875
DMR-2104427
Group (Lab)
Kyle Shen Group
Tomas Arias Group

Instructor interactions in traditional and nontraditional labs

Cornell Affiliated Author(s)
Author
D.G. Wu
A.B. Heim
M. Sundstrom
C. Walsh
N.G. Holmes
Abstract

As physics laboratory courses (labs) transition from traditional, model-verifying activities to discovery-based investigations, it becomes crucial to understand the role of the instructor in the implementation of various lab types. Prior work has started to address this need by examining either coarse-grained frequencies or fine-grained content of instructor interactions in labs. However, neither of these methods offer both a detailed and time-efficient procedure for measuring such interactions, which is required for comparisons across multiple sessions of several types of labs.

Journal
Physical Review Physics Education Research
Date Published

Interpreting angle-dependent magnetoresistance in layered materials: Application to cuprates

Cornell Affiliated Author(s)
Author
S. Musser
Debanjan Chowdhury
P.A. Lee
T. Senthil
Abstract

The evolution of the low-temperature electronic structure of the cuprate metals from the overdoped to the underdoped side has recently been addressed through angle-dependant magnetoresistance (ADMR) experiments in La1.6-xNd0.4SrxCuO4. The results show a striking difference between hole dopings p=0.24 and p=0.21, which lie on either side of a putative quantum critical point at intermediate p. Motivated by this, we here study the theory of ADMR in correlated layered materials, paying special attention to the role of angle-dependent quasiparticle weights Zk.

Journal
Physical Review B
Date Published
Funding Source
DE-FG02-03ER46076
DE- SC0008739
1745302
651446
Group (Lab)
Debanjan Chowdhury Group

Attention-based quantum tomography

Cornell Affiliated Author(s)
Author
P. Cha
P. Ginsparg
F. Wu
J. Carrasquilla
P.L. McMahon
Eun-Ah Kim
Abstract

With rapid progress across platforms for quantum systems, the problem of many-body quantum state reconstruction for noisy quantum states becomes an important challenge. There has been a growing interest in approaching the problem of quantum state reconstruction using generative neural network models. Here we propose the ‘attention-based quantum tomography’ (AQT), a quantum state reconstruction using an attention mechanism-based generative network that learns the mixed state density matrix of a noisy quantum state.

Journal
Machine Learning: Science and Technology
Date Published
Group (Lab)

Characterization of 128 × 128 MM-PAD-2.1 ASIC: A fast framing hard x-ray detector with high dynamic range

Cornell Affiliated Author(s)
Author
D. Gadkari
K.S. Shanks
H. Hu
H.T. Philipp
M.W. Tate
J. Thom-Levy
Sol Gruner
Abstract

We characterize a new x-ray Mixed-Mode Pixel Array Detector (MM-PAD-2.1) Application Specific Integrated Circuit (ASIC). Using an integrating pixel front-end with dynamic charge removal architecture, the MM-PAD-2.1 ASIC extends the maximum measurable x-ray signal (in 20 keV photon units) to > 107 x-rays/pixel/frame while maintaining a low read noise across the full dynamic range, all while imaging continuously at a frame rate of up to 10 kHz.

Journal
Journal of Instrumentation
Date Published
Group (Lab)
Sol M. Gruner Group