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Publications

Visualizing the atomic-scale origin of metallic behavior in Kondo insulators

Cornell Affiliated Author(s)
Author
H. Pirie
E. Mascot
C.E. Matt
Y. Liu
P. Chen
M.H. Hamidian
S. Saha
X. Wang
J. Paglione
G. Luke
D. Goldhaber-Gordon
C.F. Hirjibehedin
J.C.S. Davis
D.K. Morr
J.E. Hoffman
Abstract

A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. In this study, we visualized the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope.

Journal
Science
Date Published
Group (Lab)
J.C. Seamus Davis Group

Diamagnetic response and phase stiffness for interacting isolated narrow bands

Cornell Affiliated Author(s)
Author
D. Mao
Debanjan Chowdhury
Abstract

Superconductivity is a macroscopic manifestation of a quantum phenomenon where pairs of electrons delocalize and develop phase coherence over a long distance. A long-standing quest has been to address the underlying microscopic mechanisms that fundamentally limit the superconducting transition temperature, Tc . A platform which serves as an ideal playground for realizing "high"-temperature superconductors are materials where the electrons' kinetic energy is quenched and interactions provide the only energy scale in the problem.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Group (Lab)
Debanjan Chowdhury Group

Intrinsic spin Hall torque in a moiré Chern magnet

Cornell Affiliated Author(s)
Author
C.L. Tschirhart
E. Redekop
L. Li
T. Li
S. Jiang
T. Arp
O. Sheekey
T. Taniguchi
K. Watanabe
M.E. Huber
K.F. Mak
J. Shan
A.F. Young
Abstract

In spin torque magnetic memories, electrically actuated spin currents are used to switch a magnetic bit. Typically, these require a multilayer geometry including both a free ferromagnetic layer and a second layer providing spin injection. For example, spin may be injected by a non-magnetic layer exhibiting a large spin Hall effect, a phenomenon known as spin–orbit torque. Here we demonstrate a spin–orbit torque magnetic bit in a single two-dimensional system with intrinsic magnetism and strong Berry curvature.

Journal
Nature Physics
Date Published
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Discontinuous Metric Programming in Liquid Crystalline Elastomers

Cornell Affiliated Author(s)
Author
T.S. Hebner
R.G. Bowman
D. Duffy
C. Mostajeran
I. Griniasty
Itai Cohen
M. Warner
C.N. Bowman
T.J. White
Abstract

Liquid crystalline elastomers (LCEs) are shape-changing materials that exhibit large deformations in response to applied stimuli. Local control of the orientation of LCEs spatially directs the deformation of these materials to realize a spontaneous shape change in response to stimuli. Prior approaches to shape programming in LCEs utilize patterning techniques that involve the detailed inscription of spatially varying nematic fields to produce sheets. These patterned sheets deform into elaborate geometries with complex Gaussian curvatures.

Journal
ACS Applied Materials and Interfaces
Date Published
Group (Lab)
Itai Cohen Group

Evidence of frustrated magnetic interactions in a Wigner–Mott insulator

Cornell Affiliated Author(s)
Author
Yanhao Tang
Kaixiang Su
Lizhong Li
Yang Xu
Song Liu
Kenji Watanabe
Takashi Taniguchi
James Hone
Chao-Ming Jian
Cenke Xu
Kin Mak
Jie Shan
Abstract

Electrons in two-dimensional semiconductor moiré materials are more delocalized around the lattice sites than those in conventional solids1,2. The non-local contributions to the magnetic interactions can therefore be as important as the Anderson superexchange3, which makes the materials a unique platform to study the effects of competing magnetic interactions3,4. Here we report evidence of strongly frustrated magnetic interactions in a Wigner–Mott insulator at a two-thirds (2/3) filling of the moiré lattice in angle-aligned WSe2/WS2 bilayers.

Journal
Nature Nanotechnology
Date Published
Group (Lab)
Chao-Ming Jian Group
Jie Shan Group
Kin Fai Mak Group

Information geometry for multiparameter models: new perspectives on the origin of simplicity

Cornell Affiliated Author(s)
Author
K.N. Quinn
M.C. Abbott
M.K. Transtrum
B.B. Machta
J.P. Sethna
Abstract

Complex models in physics, biology, economics, and engineering are oftensloppy, meaning that the model parameters are not well determined by the model predictions for collective behavior. Many parameter combinations can vary over decades without significant changes in the predictions. This review uses information geometry to explore sloppiness and its deep relation to emergent theories. We introduce themodel manifoldof predictions, whose coordinates are the model parameters. Itshyperribbonstructure explains why only a few parameter combinations matter for the behavior.

Journal
Reports on progress in physics. Physical Society (Great Britain)
Date Published
Group (Lab)
James Sethna Group

Structural evolution of the kagome superconductors A V3Sb5 (A = K, Rb, and Cs) through charge density wave order

Cornell Affiliated Author(s)
Author
L. Kautzsch
B.R. Ortiz
K. Mallayya
J. Plumb
G. Pokharel
J.P.C. Ruff
Z. Islam
Eun-Ah Kim
R. Seshadri
S.D. Wilson
Abstract

The kagome superconductors KV3Sb5, RbV3Sb5, and CsV3Sb5 are known to display charge density wave (CDW) order which impacts the topological characteristics of their electronic structure. Details of their structural ground states and how they evolve with temperature are revealed here using single crystal x-ray crystallographic refinements as a function of temperature, carried out with synchrotron radiation. The compounds KV3Sb5 and RbV3Sb5 present 2×2×2 superstructures in the Fmmm space group with a staggered trihexagonal deformation of vanadium layers.

Journal
Physical Review Materials
Date Published
Group (Lab)
Eun-Ah Kim 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
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)
Eun-Ah Kim Group