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Publications

Visualizing probabilistic models in Minkowski space with intensive symmetrized Kullback-Leibler embedding

Cornell Affiliated Author(s)
Author
H.K. Teoh
K.N. Quinn
J. Kent-Dobias
C.B. Clement
Q. Xu
J.P. Sethna
Abstract

We show that the predicted probability distributions for any N-parameter statistical model taking the form of an exponential family can be explicitly and analytically embedded isometrically in a N+N-dimensional Minkowski space. That is, the model predictions can be visualized as control parameters are varied, preserving the natural distance between probability distributions. All pairwise distances between model instances are given by the symmetrized Kullback-Leibler divergence.

Journal
Physical Review Research
Date Published
Funding Source
1719490
Group (Lab)
James Sethna Group

Linear resistivity and Sachdev-Ye-Kitaev (SYK) spin liquid behavior in a quantum critical metal with spin-1=2 fermions

Cornell Affiliated Author(s)
Author
P. Cha
N. Wentzell
O. Parcollet
A. Georges
Eun-Ah Kim
Abstract

"Strange metals" with resistivity depending linearly on temperature T down to low T have been a long-standing puzzle in condensed matter physics. Here, we consider a lattice model of itinerant spin-1=2 fermions interacting via onsite Hubbard interaction and random infinite-ranged spin-spin interaction.We show that the quantum critical point associated with the melting of the spin-glass phase by charge fluctuations displays non-Fermi liquid behavior, with local spin dynamics identical to that of the Sachdev-Ye-Kitaev family of models.

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

Gate-tunable spin waves in antiferromagnetic atomic bilayers

Cornell Affiliated Author(s)
Author
X.-X. Zhang
L. Li
D. Weber
J. Goldberger
K.F. Mak
J. Shan
Abstract

Remarkable properties of two-dimensional (2D) layer magnetic materials, which include spin filtering in magnetic tunnel junctions and the gate control of magnetic states, were demonstrated recently1–12. Whereas these studies focused on static properties, dynamic magnetic properties, such as excitation and control of spin waves, remain elusive. Here we investigate spin-wave dynamics in antiferromagnetic CrI3 bilayers using an ultrafast optical pump/magneto-optical Kerr probe technique.

Journal
Nature Materials
Date Published
Funding Source
DMR-1807810
1420451
1719875
1807810
FA9550-19-1-0390
DMR-1719875
DMR-1420451
WE6480/1
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Realization of Epitaxial Thin Films of the Topological Crystalline Insulator Sr3SnO

Cornell Affiliated Author(s)
Author
Y. Ma
A. Edgeton
H. Paik
B.D. Faeth
C.T. Parzyck
B. Pamuk
S.-L. Shang
Z.-K. Liu
K.M. Shen
D.G. Schlom
C.-B. Eom
Abstract

Topological materials are derived from the interplay between symmetry and topology. Advances in topological band theories have led to the prediction that the antiperovskite oxide Sr3SnO is a topological crystalline insulator, a new electronic phase of matter where the conductivity in its (001) crystallographic planes is protected by crystallographic point group symmetries. Realization of this material, however, is challenging.

Journal
Advanced Materials
Date Published
Funding Source
ACI-1548562
DE-AC02-05CH11231
DMR‐1629270
ECCS‐1542081
ACI‐1548562
DE‐AC02‐05CH11231
DMR‐1539918
FA9550‐15‐1‐0334
DMR‐1719875
Group (Lab)
Kyle Shen Group

Ultracold Electrons via Near-Threshold Photoemission from Single-Crystal Cu(100)

Cornell Affiliated Author(s)
Author
S. Karkare
G. Adhikari
W.A. Schroeder
J.K. Nangoi
Tomas Arias
J. Maxson
H. Padmore
Abstract

Achieving a low mean transverse energy or temperature of electrons emitted from the photocathode-based electron sources is critical to the development of next-generation and compact X-ray free electron lasers and ultrafast electron diffraction, spectroscopy, and microscopy experiments. In this Letter, we demonstrate a record low mean transverse energy of 5 meV from the cryo-cooled (100) surface of copper using near-threshold photoemission.

Journal
Physical Review Letters
Date Published
Funding Source
PHY-1549132
DE-AC02-05CH11231
DE-SC0017621
KC0407-ALSJNT-I0013
Group (Lab)
Tomas Arias Group

Topological phase transition on the edge of two-dimensional Z2 topological order

Cornell Affiliated Author(s)
Author
Wei-Qiang Chen
Chao-Ming Jian
Liang Kong
Yi-Zhuang You
Hao Zheng
Abstract

The unified mathematical theory of gapped and gapless edges of two-dimensional (2d) topological orders was developed by two of the authors. According to this theory, the critical point of a purely edge topological phase transition of a 2d topological order can be mathematically characterized by an enriched fusion category. In this work, we provide a physical proof of this fact in a concrete example: the 2d Z2 topological order. In particular, we construct an enriched fusion category, which describes a gappable nonchiral gapless edge of the 2d Z2 topological order.

Journal
Physical Review B
Date Published
Funding Source
11131008
11871078
11971219
2019B121203002
GBMF4304
11674151
11861161001
ZDSYS20170303165926217
2016YFA0300300
Group (Lab)
Chao-Ming Jian Group

Chemistry of the spin- 12 kagome Heisenberg antiferromagnet

Cornell Affiliated Author(s)
Author
Y. Yao
C.J. Umrigar
V. Elser
Abstract

We believe that a necessary first step in understanding the ground-state properties of the spin-12 kagome Heisenberg antiferromagnet is a better understanding of this model's very large number of low-energy singlet states. A description of the low-energy states that is both accurate and amenable for numerical work may ultimately prove to have greater value than knowing only what these properties are, in particular, when they turn on the delicate balance of many small energies.

Journal
Physical Review B
Date Published
Funding Source
ACI-1445606
ACI-1547580
1445606
FA9550-18-1-0095
Group (Lab)
Cyrus Umrigar Group
Veit Elser Group

Bidirectional Self-Folding with Atomic Layer Deposition Nanofilms for Microscale Origami

Cornell Affiliated Author(s)
Author
B. Bircan
M.Z. Miskin
R.J. Lang
M.C. Cao
K.J. Dorsey
M.G. Salim
W. Wang
D.A. Muller
P.L. McEuen
Itai Cohen
Abstract

Origami design principles are scale invariant and enable direct miniaturization of origami structures provided the sheets used for folding have equal thickness to length ratios. Recently, seminal steps have been taken to fabricate microscale origami using unidirectionally actuated sheets with nanoscale thickness. Here, we extend the full power of origami-inspired fabrication to nanoscale sheets by engineering bidirectional folding with 4 nm thick atomic layer deposition (ALD) SiNx-SiO2 bilayer films.

Journal
Nano Letters
Date Published
Funding Source
1542081
1719875
NNCI-1542081
W911NF-18–1–0032
DMR-1719875
Group (Lab)
Itai Cohen Group
Paul McEuen Group