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Publications

Magnetic excitations in the square-lattice iridate Ba2IrO4

Cornell Affiliated Author(s)
Author
J.P. Clancy
H. Gretarsson
A. Lupascu
J.A. Sears
Z. Nie
M.H. Upton
J. Kim
Z. Islam
M. Uchida
D.G. Schlom
K.M. Shen
Y.-J. Kim
Abstract

We report a resonant inelastic x-ray scattering investigation of ultrathin epitaxial films of Ba2IrO4, and compare their low-energy magnetic and spin-orbit excitations to those of their sister compound Sr2IrO4. Due to the 180∘ Ir-O-Ir bond, the bandwidth of the magnon and spin orbiton is significantly larger in Ba2IrO4, making it difficult to describe these two types of excitations as separate well-defined quasiparticles. Both types of excitations are found to be quite sensitive to the effect of epitaxial strain.

Journal
Physical Review B
Date Published
Funding Source
DMR-2104427
FA9550-21-1-0168
DE-AC02-06CH11357
Group (Lab)
Kyle Shen Group

Continuous Mott Transition in Moiré Semiconductors: Role of Long-Wavelength Inhomogeneities

Cornell Affiliated Author(s)
Author
S. Kim
T. Senthil
Debanjan Chowdhury
Abstract

Recent experiments in moiré transition metal dichalcogenide materials have reported the observation of a continuous bandwidth-tuned transition from a metal to a paramagnetic Mott insulator at a fixed filling of one electron per moiré unit cell. The electrical transport measurements reveal a number of puzzling features that are seemingly at odds with the theoretical expectations of an interaction-induced, but disorder-free, bandwidth-tuned metal-insulator transition.

Journal
Physical Review Letters
Date Published
Group (Lab)
Debanjan Chowdhury Group

Taking on a manager role can support women's physics lab identity development

Cornell Affiliated Author(s)
Author
E.M. Stump
M. Dew
S. Jeon
N.G. Holmes
Abstract

Prior research has indicated that students in the undergraduate physics lab divide work inequitably with regard to gender. In this work, we further probed women's experiences in lab group work, focusing on women who take on managerial and leadership roles in the lab. We interviewed and surveyed women enrolled in a sophomore-level project-based lab course, drawing on a practice-linked identity framework to characterize their opportunities for engagement and identity development within the course.

Journal
Physical Review Physics Education Research
Date Published
Funding Source
DGE-2139899
DUE-1836617
Group (Lab)
Natasha Holmes Group

Melting of generalized Wigner crystals in transition metal dichalcogenide heterobilayer Moiré systems (Nature Communications, (2022), 13, 1, (7098), 10.1038/s41467-022-34683-x)

Cornell Affiliated Author(s)
Author
M. Matty
Eun-Ah Kim
Abstract

The original version of this Article contained an error in the Acknowledgements, which incorrectly read ‘The authors acknowledge support by the NSF [Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM)] under cooperative agreement no. DMR-U638986.’. The correct version states ‘DMR-1539918’ in place of ‘DMRU638986’. This has been corrected in both the PDF and HTML versions of the Article. © The Author(s) 2023.

Journal
Nature Communications
Date Published
Group (Lab)

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
Funding Source
PHY-1549132
DE-SC0020575
DE-SC0021092
Group (Lab)
Tomas Arias Group

Steering self-organisation through confinement

Cornell Affiliated Author(s)
Author
N.A.M. Araújo
L.M.C. Janssen
T. Barois
G. Boffetta
Itai Cohen
A. Corbetta
O. Dauchot
M. Dijkstra
W.M. Durham
A. Dussutour
S. Garnier
H. Gelderblom
R. Golestanian
L. Isa
G.H. Koenderink
H. Löwen
R. Metzler
M. Polin
C.P. Royall
A. Šarić
A. Sengupta
C. Sykes
V. Trianni
I. Tuval
N. Vogel
J.M. Yeomans
I. Zuriguel
A. Marin
G. Volpe
Abstract

Self-organisation is the spontaneous emergence of spatio-temporal structures and patterns from the interaction of smaller individual units. Examples are found across many scales in very different systems and scientific disciplines, from physics, materials science and robotics to biology, geophysics and astronomy. Recent research has highlighted how self-organisation can be both mediated and controlled by confinement.

Journal
Soft Matter
Date Published
Group (Lab)
Itai Cohen Group

A Drift-Diffusion Based Modeling and Optimization Framework for Nanoscale Spin-Orbit Torque Devices

Cornell Affiliated Author(s)
Author
Piyush Kumar
Yu-Ching Liao
Daniel Ralph
Azad Naeemi
Abstract

We present a comprehensive set of experimentally validated/calibrated models that capture the physics of the nanoscale spin-orbit torque (SOT) devices. We consider various effects that are prominent at nanoscale including incomplete current redistribution, interface spin mixing, and nonuniform resistivity that were ignored in the prior modeling efforts. We develop a formalism based on drift-diffusion equations and the transfer matrix method to accurately estimate spin current distribution.

Journal
Institute of Electrical and Electronics Engineers (IEEE)
Date Published

Exciton density waves in Coulomb-coupled dual moiré lattices

Cornell Affiliated Author(s)
Author
Y. Zeng
Z. Xia
R. Dery
K. Watanabe
T. Taniguchi
J. Shan
K.F. Mak
Abstract

Strongly correlated bosons in a lattice are a platform that can realize rich bosonic states of matter and quantum phase transitions1. While strongly correlated bosons in a lattice have been studied in cold-atom experiments2–4, their realization in a solid-state system has remained challenging5. Here we trap interlayer excitons–bosons composed of bound electron–hole pairs, in a lattice provided by an angle-aligned WS2/bilayer WSe2/WS2 multilayer. The heterostructure supports Coulomb-coupled triangular moiré lattices of nearly identical period at the top and bottom interfaces.

Journal
Nature Materials
Date Published
Funding Source
DMR-2114535
N00014-21-1-2471
NNCI-2025233
DE-SC0019481
JPMJCR15F3
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Machine learning discovery of new phases in programmable quantum simulator snapshots

Cornell Affiliated Author(s)
Author
C. Miles
R. Samajdar
S. Ebadi
T.T. Wang
H. Pichler
S. Sachdev
M.D. Lukin
M. Greiner
K.Q. Weinberger
Eun-Ah Kim
Abstract

Machine learning has recently emerged as a promising approach for studying complex phenomena characterized by rich datasets. In particular, data-centric approaches lead to the possibility of automatically discovering structures in experimental datasets that manual inspection may miss. Here, we introduce an interpretable unsupervised-supervised hybrid machine learning approach, the hybrid-correlation convolutional neural network (hybrid-CCNN), and apply it to experimental data generated using a programmable quantum simulator based on Rydberg atom arrays.

Journal
Physical Review Research
Date Published
Group (Lab)