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Publications

Valley-Coherent Quantum Anomalous Hall State in AB-Stacked MoTe2/ W S e2 Bilayers

Cornell Affiliated Author(s)
Author
Z. Tao
B. Shen
S. Jiang
T. Li
L. Li
L. Ma
W. Zhao
J. Hu
K. Pistunova
K. Watanabe
T. Taniguchi
T.F. Heinz
K.F. Mak
J. Shan
Abstract

Moiré materials provide fertile ground for the correlated and topological quantum phenomena. Among them, the quantum anomalous Hall (QAH) effect, in which the Hall resistance is quantized even under zero magnetic field, is a direct manifestation of the intrinsic topological properties of a material and an appealing attribute for low-power electronics applications. The QAH effect has been observed in both graphene and transition metal dichalcogenide (TMD) moiré materials. It is thought to arise from the interaction-driven valley polarization of the narrow moiré bands.

Journal
Physical Review X
Date Published
Funding Source
DMR-1807810
NNCI-2025233
FA9550-19-1-0390
GBMF11563
GBMF9462
DE-SC0019481
FWP-100459
JPMJCR15F3
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Realization of the Haldane Chern insulator in a moiré lattice

Author
W. Zhao
K. Kang
Y. Zhang
P. Knuppel
Z. Tao
L. Li
C.L. Tschirhart
E. Redekop
K. Watanabe
T. Taniguchi
A.F. Young
J. Shan
K.F. Mak
Abstract

The Chern insulator displays a quantized Hall effect without Landau levels. Theoretically, this state can be realized by engineering complex next-nearest-neighbour hopping in a honeycomb lattice—the so-called Haldane model. Despite its profound effect on the field of topological physics and recent implementation in cold-atom experiments, the Haldane model has not yet been realized in solid-state materials.

Journal
Nature Physics
Date Published
Funding Source
DMR-1807810
FA9550-19-1-0390
FA9550-20-1-0219
GBMF9471
W911NF-20-2-0166
DE-SC0019481
NNCI-2025233
JPMJCR15F3
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Exchange Bias Between van der Waals Materials: Tilted Magnetic States and Field-Free Spin–Orbit-Torque Switching

Cornell Affiliated Author(s)
Author
T.M.J. Cham
R.J. Dorrian
X.S. Zhang
A.H. Dismukes
D.G. Chica
A.F. May
X. Roy
D.A. Muller
D.C. Ralph
Y.K. Luo
Abstract

Magnetic van der Waals heterostructures provide a unique platform to study magnetism and spintronics device concepts in the 2D limit. Here, studies of exchange bias from the van der Waals antiferromagnet CrSBr acting on the van der Waals ferromagnet Fe3GeTe2 (FGT) are reported. The orientation of the exchange bias is along the in-plane easy axis of CrSBr, perpendicular to the out-of-plane anisotropy of the FGT, inducing a strongly tilted magnetic configuration in the FGT.

Journal
Advanced Materials
Date Published

Fully Ab Initio Approach to Inelastic Atom-Surface Scattering

Cornell Affiliated Author(s)
Author
M.M. Kelley
R. Sundararaman
T.A. Arias
Abstract

We introduce a fully ab initio theory for inelastic scattering of any atom from any surface exciting single phonons, and apply the theory to helium scattering from Nb(100). The key aspect making our approach general is a direct first-principles evaluation of the scattering atom-electron vertex. By correcting misleading results from current state-of-the-art theories, this fully ab initio approach will be critical in guiding and interpreting experiments that adopt next-generation, nondestructive atomic beam scattering. © 2024 American Physical Society.

Journal
Physical Review Letters
Date Published
Funding Source
PHY-1549132
Group (Lab)
Tomas Arias Group

Dehydration drives damage in the freezing of brittle hydrogels

Cornell Affiliated Author(s)
Author
Shaohua Yang
Dominic Gerber
Yanxia Feng
Nicolas Bain
Matthias Kuster
Laura de Lorenzis
Ye Xu
Eric Dufresne
Robert Style
Abstract

It is widely known that freezing breaks soft, wet materials. However, the mechanism underlying this damage is still not clear. To understand this process, we freeze model, brittle hydrogel samples, while observing the growth of ice-filled cracks that break these apart. We show that damage is not caused by the expansion of water upon freezing, or the growth of ice-filled cavities in the hydrogel. Instead, local ice growth dehydrates the surrounding hydrogel, leading to drying-induced fracture.

Journal
arXiv e-prints
Date Published
Research Area
Group (Lab)
Eric Dufresne Group

Tapestry of dualities in decohered quantum error correction codes

Cornell Affiliated Author(s)
Author
Kaixiang Su
Zhou Yang
Chao-Ming Jian
Abstract

Quantum error correction (QEC) codes protect quantum information from errors due to decoherence. Many of them also serve as prototypical models for exotic topological quantum matters. Investigating the behavior of the QEC codes under decoherence sheds light on not only the codes' robustness against errors but also new out-of-equilibrium quantum phases driven by decoherence. The phase transitions, including the error threshold, of the decohered QEC codes can be probed by the systems' Rényi entropies SR with different Rényi indices R.

Journal
arXiv e-prints
Date Published
Group (Lab)
Chao-Ming Jian Group

Thermally generated spin current in the topological insulator Bi2Se3

Cornell Affiliated Author(s)
Author
R. Jain
M. Stanley
A. Bose
A.R. Richardella
X.S. Zhang
T. Pillsbury
D.A. Muller
N. Samarth
D.C. Ralph
Abstract

We present measurements of thermally generated transverse spin currents in the topological insulator Bi2Se3, thereby completing measurements of interconversions among the full triad of thermal gradients, charge currents, and spin currents. We accomplish this by comparing the spin Nernst magneto-thermopower to the spin Hall magnetoresistance for bilayers of Bi2Se3/CoFeB. We find that Bi2Se3 does generate substantial thermally driven spin currents.

Journal
Science Advances
Date Published

Large spin–orbit torque in bismuthate-based heterostructures

Cornell Affiliated Author(s)
Author
A.L. Edgeton
I.A. Harris
N.G. Campbell
Y. Chai
M.M. Mazur
G. Gurung
X. Huang
S. Susarla
E.Y. Tsymbal
D.C. Ralph
T. Nan
M.S. Rzchowski
R. Ramesh
C.-B. Eom
Abstract

The wider application of spintronic devices requires the development of new material platforms that can efficiently be used to manipulate spin. Bismuthate-based superconductors are centrosymmetric systems that are generally thought to offer weak spin–orbit coupling. Here we report a large spin–orbit torque driven by spin polarization generated in heterostructures based on the bismuthate BaPb1−xBixO3 (which is in a non-superconducting state). Using spin-torque ferromagnetic resonance and d.c.

Journal
Nature Electronics
Date Published

High-throughput ab initio design of atomic interfaces using InterMatch

Cornell Affiliated Author(s)
Author
E. Gerber
S.B. Torrisi
S. Shabani
E. Seewald
J. Pack
J.E. Hoffman
C.R. Dean
A.N. Pasupathy
E.-A. Kim
Abstract

Forming a hetero-interface is a materials-design strategy that can access an astronomically large phase space. However, the immense phase space necessitates a high-throughput approach for an optimal interface design. Here we introduce a high-throughput computational framework, InterMatch, for efficiently predicting charge transfer, strain, and superlattice structure of an interface by leveraging the databases of individual bulk materials.

Journal
Nature Communications
Date Published
Group (Lab)

Realizing a tunable honeycomb lattice in ABBA-stacked twisted double bilayer WSe2

Cornell Affiliated Author(s)
Author
Haining Pan
Eun-Ah Kim
Chao-Ming Jian
Abstract

The ideal honeycomb lattice, featuring sublattice and SU(2) spin rotation symmetries, is a fundamental model for investigating quantum matters with topology and correlations. With the rise of the moiré-based design of model systems, realizing a tunable and symmetric honeycomb lattice system with a narrow bandwidth can open access to new phases and insights. We propose the ABBA-stacked twisted double bilayer WSe2 as a realistic and tunable platform for reaching this goal.

Journal
Physical Review Research
Date Published
Group (Lab)
Chao-Ming Jian Group