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Publications

Learning grammar with a divide-and-concur neural network

Cornell Affiliated Author(s)
Author
S. Deyo
V. Elser
Abstract

We implement a divide-and-concur iterative projection approach to context-free grammar inference. Unlike most state-of-the-art models of natural language processing, our method requires a relatively small number of discrete parameters, making the inferred grammar directly interpretable - one can read off from a solution how to construct grammatically valid sentences. Another advantage of our approach is the ability to infer meaningful grammatical rules from just a few sentences, compared to the hundreds of gigabytes of training data many other models employ.

Journal
Physical Review E
Date Published
Group (Lab)
Veit Elser Group

Density Matrix Renormalization Group for Continuous Quantum Systems

Cornell Affiliated Author(s)
Author
S. Dutta
A. Buyskikh
A.J. Daley
E.J. Mueller
Abstract

We introduce a versatile and practical framework for applying matrix product state techniques to continuous quantum systems. We divide space into multiple segments and generate continuous basis functions for the many-body state in each segment. By combining this mapping with existing numerical density matrix renormalization group routines, we show how one can accurately obtain the ground-state wave function, spatial correlations, and spatial entanglement entropy directly in the continuum.

Journal
Physical Review Letters
Date Published
Funding Source
PHY-1806357
PHY-2110250
EP/P009565/1

Giant bulk spin–orbit torque and efficient electrical switching in single ferrimagnetic FeTb layers with strong perpendicular magnetic anisotropy

Cornell Affiliated Author(s)
Author
Qianbiao Liu
Lijun Zhu
Xiyue Zhang
David Muller
Daniel Ralph
Abstract

Efficient manipulation of antiferromagnetically coupled materials that are integration-friendly and have strong perpendicular magnetic anisotropy (PMA) is of great interest for low-power, fast, dense magnetic storage and computing. Here, we report a distinct, giant bulk damping-like spin-orbit torque in strong-PMA ferrimagnetic Fe100-xTbx single layers that are integration-friendly (composition-uniform, amorphous, and sputter-deposited).

Journal
AIP Publishing
Date Published
Funding Source
DMR-1719875
N00014-19-1-2143
D18AC00009
NNCI-2025233
XDB44000000
201906460052
E2SEBB01

In vitro attachment and symmetry breaking of a human embryo model assembled from primed embryonic stem cells

Cornell Affiliated Author(s)
Author
M. Simunovic
E.D. Siggia
A.H. Brivanlou
Abstract

Our knowledge of the molecular mechanisms surrounding human embryo implantation and gastrulation is lacking, largely due to technical and ethical limitations of experimenting with human embryos. Alternatives to human embryos have been reported, in which 3D clusters of embryonic stem cells are differentiated in a stepwise manner to model aspects of human embryogenesis. Yet it remains challenging to model the events past attachment.

Journal
Cell Stem Cell
Date Published
Funding Source
NGP10152
Research Area

Cilia metasurfaces for electronically programmable microfluidic manipulation

Cornell Affiliated Author(s)
Author
W. Wang
Q. Liu
I. Tanasijevic
M.F. Reynolds
A.J. Cortese
M.Z. Miskin
M.C. Cao
D.A. Muller
A.C. Molnar
E. Lauga
P.L. McEuen
Itai Cohen
Abstract

Cilial pumping is a powerful strategy used by biological organisms to control and manipulate fluids at the microscale. However, despite numerous recent advances in optically, magnetically and electrically driven actuation, development of an engineered cilial platform with the potential for applications has remained difficult to realize1–6. Here we report on active metasurfaces of electronically actuated artificial cilia that can create arbitrary flow patterns in liquids near a surface.

Journal
Nature
Date Published
Funding Source
EFMA-1935252
NNCI-2025233
ARO W911NF-18-1-0032
DMR-1719875
682754
FA9550-16-1-0031
Group (Lab)
Itai Cohen Group
Paul McEuen Group

Strong magnetoelastic coupling in Mn3X (X=Ge, Sn)

Cornell Affiliated Author(s)
Author
Florian Theuss
Sayak Ghosh
Taishi Chen
Oleg Tchernyshyov
Satoru Nakatsuji
B. Ramshaw
Abstract

We measure the full elastic tensors of Mn3Ge and Mn3Sn as a function of temperature through their respective antiferromagnetic phase transitions. Large discontinuities in the bulk moduli at the Néel transitions indicate strong magnetoelastic coupling in both compounds. Strikingly, the discontinuities are nearly a factor of 10 larger in Mn3Ge than in Mn3Sn. We use the magnitudes of the discontinuities to calculate the pressure derivatives of the Néel temperature, which are 39 K/GPa 14.3 K/GPa for Mn3Ge and Mn3Sn, respectively.

Journal
Physical Review B
Date Published
Group (Lab)
Brad Ramshaw Group

Recovery mechanisms in the dragonfly righting reflex

Cornell Affiliated Author(s)
Author
Z.J. Wang
Melfi Jr., J.
A. Leonardo
Abstract

Insects have evolved sophisticated reflexes to right themselves in mid-air. Their recovery mechanisms involve complex interactions among the physical senses, muscles, body, and wings, and they must obey the laws of flight. We sought to understand the key mechanisms involved in dragonfly righting reflexes and to develop physics-based models for understanding the control strategies of flight maneuvers.

Journal
Science
Date Published
Research Area
Group (Lab)
Z. Jane Wang Group

Tilted spin current generated by the collinear antiferromagnet ruthenium dioxide

Cornell Affiliated Author(s)
Author
Arnab Bose
Nathaniel Schreiber
Rakshit Jain
Ding-Fu Shao
Hari Nair
Jiaxin Sun
Xiyue Zhang
David Muller
Evgeny Tsymbal
Darrell Schlom
Daniel Ralph
Abstract

Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. It also influences how these spin currents generate spin-transfer torques in magnetic devices. Here we show that an out-of-plane damping-like torque can be generated in ruthenium dioxide (RuO2)/permalloy devices when the Néel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane.

Journal
Springer Science and Business Media LLC
Date Published
Funding Source
DE-SC0017671
GBMF9073
2039380
DMR-1719875
DMR-1420645
DMR-1429155
NNCI-2025233

Fermi surface transformation at the pseudogap critical point of a cuprate superconductor

Author
Yawen Fang
Gael Grissonnanche
Anaëlle Legros
Simon Verret
Francis Laliberté
C. Collignon
Amirreza Ataei
Maxime Dion
Jianshi Zhou
David Graf
Michael Lawler
Paul Goddard
Louis Taillefer
B. Ramshaw
Abstract

The nature of the pseudogap phase remains a major puzzle in our understanding of cuprate high-temperature superconductivity. Whether or not this metallic phase is defined by any of the reported broken symmetries, the topology of its Fermi surface remains a fundamental open question. Here we use angle-dependent magnetoresistance (ADMR) to measure the Fermi surface of the La1.6–xNd0.4SrxCuO4 cuprate. Outside the pseudogap phase, we fit the ADMR data and extract a Fermi surface geometry that is in excellent agreement with angle-resolved photoemission data.

Journal
Nature Physics
Date Published
Funding Source
681260
MRSEC DMR-1720595
DMR-1644779
DMR-1752784
GBMF5306
Group (Lab)
Brad Ramshaw Group
Michael Lawler Group

In-situ angle-resolved photoemission spectroscopy of copper-oxide thin films synthesized by molecular beam epitaxy

Cornell Affiliated Author(s)
Author
C.K. Kim
I.K. Drozdov
K. Fujita
J.C.S. Davis
I. Božović
T. Valla
Abstract

Angle-resolved photoemission spectroscopy (ARPES) is the key momentum-resolved technique for direct probing of the electronic structure of a material. However, since it is highly surface-sensitive, it has been applied to a relatively small set of complex oxides that can be easily cleaved in ultra-high vacuum. Here we describe a new multi-module system at Brookhaven National Laboratory (BNL) in which an oxide molecular beam epitaxy (OMBE) is interconnected with an ARPES and a spectroscopic-imaging scanning tunneling microscopy (SI-STM) module.

Journal
Journal of Electron Spectroscopy and Related Phenomena
Date Published
Group (Lab)
J.C. Seamus Davis Group