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Publications

Magic continuum in a twisted bilayer square lattice with staggered flux

Cornell Affiliated Author(s)
Author
Zhu-Xi Luo
Cenke Xu
Chao-Ming Jian
Abstract

We derive the general continuum model for a bilayer system of staggered-flux square lattices, with arbitrary elastic deformation in each layer. Applying this general continuum model to the case where the two layers are rigidly rotated relative to each other by a small angle, we obtain the band structure of the twisted bilayer staggered-flux square lattice. We show that this band structure exhibits a magic continuum in the sense that an exponential reduction of the Dirac velocity and bandwidths occurs in a large parameter regime.

Journal
Physical Review B
Date Published
Funding Source
DMR-1920434
Group (Lab)
Chao-Ming Jian Group

Orbital optimization in selected configuration interaction methods

Cornell Affiliated Author(s)
Author
Yuan Yao
C. Umrigar
Abstract

We study several approaches to orbital optimization in selected configuration interaction (SCI) plus perturbation theory methods and test them on the ground and excited states of three molecules using the semistochastic heat-bath configuration interaction method. We discuss the ways in which the orbital optimization problem in SCI resembles and differs from that in complete active space self-consistent field.

Journal
Journal of Chemical Theory and Computation
Date Published
Funding Source
ACI-1445606
ACI-1547580
1445606
FA9550-18-1-0095
Group (Lab)
Cyrus Umrigar Group

Torsional Stiffness of Extended and Plectonemic DNA

Cornell Affiliated Author(s)
Author
X. Gao
Y. Hong
F. Ye
J.T. Inman
M.D. Wang
Abstract

DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression. However, direct measurements of these parameters are experimentally challenging. Here, we present a constant-extension method integrated into an angular optical trap to directly measure torque during DNA supercoiling. We measured the twist persistence length of extended DNA to be 22 nm under an extremely low force (∼0.02 pN) and the twist persistence length of plectonemic DNA to be 24 nm.

Journal
Physical Review Letters
Date Published
Research Area
Group (Lab)
Michelle Wang Group

Differential compartmentalization of BMP4/NOGGIN requires NOGGIN trans-epithelial transport

Cornell Affiliated Author(s)
Author
T. Phan-Everson
F. Etoc
S. Li
S. Khodursky
A. Yoney
A.H. Brivanlou
E.D. Siggia
Abstract

Using self-organizing human models of gastrulation, we previously showed that (1) BMP4 initiates the cascade of events leading to gastrulation, (2) BMP4 signal reception is restricted to the basolateral domain, and (3) in a human-specific manner, BMP4 directly induces the expression of NOGGIN. Here, we report the surprising discovery that in human epiblasts, NOGGIN and BMP4 were secreted into opposite extracellular spaces. Interestingly, apically presented NOGGIN could inhibit basally delivered BMP4.

Journal
Developmental Cell
Date Published
Funding Source
1946429
R01 GM101653
R01HD080699
Research Area

Stripe phases in WSe2/WS2 moiré superlattices

Cornell Affiliated Author(s)
Author
C. Jin
Z. Tao
T. Li
Y. Xu
Y. Tang
J. Zhu
S. Liu
K. Watanabe
T. Taniguchi
J.C. Hone
L. Fu
J. Shan
K.F. Mak
Abstract

Stripe phases, in which the rotational symmetry of charge density is spontaneously broken, occur in many strongly correlated systems with competing interactions1–11. However, identifying and studying such stripe phases remains challenging. Here we uncover stripe phases in WSe2/WS2 moiré superlattices by combining optical anisotropy and electronic compressibility measurements. We find strong electronic anisotropy over a large doping range peaked at 1/2 filling of the moiré superlattice. The 1/2 state is incompressible and assigned to an insulating stripe crystal phase.

Journal
Nature Materials
Date Published
Funding Source
N00014-18-1-2368 Here
FA9550-20-1-0219
DE-SC0019481
W911NF-17-1-0605
JPMJCR15F3
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Superconducting Quantum Metamaterials from Convergence of Soft and Hard Condensed Matter Science

Cornell Affiliated Author(s)
Author
P.A. Beaucage
R.B. Van Dover
F.J. DiSalvo
Sol Gruner
U. Wiesner
Abstract

Superconducting quantum metamaterials are expected to exhibit a variety of novel properties, but have been a major challenge to prepare as a result of the lack of appropriate synthetic routes to high-quality materials. Here, the discovery of synthesis routes to block copolymer (BCP) self-assembly-directed niobium nitrides and carbonitrides is described. The resulting materials exhibit unusual structure retention even at temperatures as high as 1000 °C and resulting critical temperature, Tc, values comparable to their bulk analogues.

Journal
Advanced Materials
Date Published
Funding Source
1707836
DMR‐1707836
DE‐SC0017631
DGE‐1650441
DMR‐1332208
DMR‐1719875
Group (Lab)
Sol M. Gruner Group

Interfacial Electron-Phonon Coupling Constants Extracted from Intrinsic Replica Bands in Monolayer FeSe/SrTi O3

Cornell Affiliated Author(s)
Author
B.D. Faeth
S. Xie
S. Yang
J.K. Kawasaki
J.N. Nelson
S. Zhang
C. Parzyck
P. Mishra
C. Li
C. Jozwiak
A. Bostwick
E. Rotenberg
D.G. Schlom
K.M. Shen
Abstract

The observation of replica bands by angle-resolved photoemission spectroscopy has ignited interest in the study of electron-phonon coupling at low carrier densities, particularly in monolayer FeSe/SrTiO3, where the appearance of replica bands has motivated theoretical work suggesting that the interfacial coupling of electrons in the FeSe layer to optical phonons in the SrTiO3 substrate might contribute to the enhanced superconducting pairing temperature.

Journal
Physical Review Letters
Date Published
Funding Source
DMR-1539918
DMR-1709255
FA9550-15-1-0474
FA9550-21-1-0168
DGE-1650441
GBMF3850
DE-AC02-05CH11231
ECCS-1542081
DMR-1719875
Group (Lab)
Kyle Shen Group

Discovery of a Cooper-pair density wave state in a transition-metal dichalcogenide

Cornell Affiliated Author(s)
Author
X. Liu
Y.X. Chong
R. Sharma
J.C.S. Davis
Abstract

Pair density wave (PDW) states are defined by a spatially modulating superconductive order parameter. To search for such states in transition-metal dichalcogenides (TMDs), we used high-speed atomicresolution scanned Josephson-tunneling microscopy. We detected a PDW state whose electron-pair density and energy gap modulate spatially at the wave vectors of the preexisting charge density wave (CDW) state.

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

Correlator convolutional neural networks as an interpretable architecture for image-like quantum matter data

Cornell Affiliated Author(s)
Author
C. Miles
A. Bohrdt
R. Wu
C. Chiu
M. Xu
G. Ji
M. Greiner
K.Q. Weinberger
E. Demler
Eun-Ah Kim
Abstract

Image-like data from quantum systems promises to offer greater insight into the physics of correlated quantum matter. However, the traditional framework of condensed matter physics lacks principled approaches for analyzing such data. Machine learning models are a powerful theoretical tool for analyzing image-like data including many-body snapshots from quantum simulators. Recently, they have successfully distinguished between simulated snapshots that are indistinguishable from one and two point correlation functions.

Journal
Nature Communications
Date Published
Group (Lab)

Spin Dynamics Slowdown near the Antiferromagnetic Critical Point in Atomically Thin FePS3

Cornell Affiliated Author(s)
Author
X.-X. Zhang
S. Jiang
J. Lee
C. Lee
K.F. Mak
J. Shan
Abstract

Two-dimensional (2D) magnetic materials have attracted much recent interest with unique properties emerging at the few-layer limit. Beyond the reported impacts on the static magnetic properties, the effects of reducing the dimensionality on the magnetization dynamics are also of fundamental interest and importance for 2D device development. In this report, we investigate the spin dynamics in atomically thin antiferromagnetic FePS3 of varying layer numbers using ultrafast pump-probe spectroscopy.

Journal
Nano Letters
Date Published
Funding Source
DMR-1807810
FA9550-19-1-0390
FA9550-20-1-0219
NRF- 2020R1A2C2014687
Group (Lab)
Jie Shan Group
Kin Fai Mak Group