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Publications

Restructuring physics labs to cultivate sense of student agency

Cornell Affiliated Author(s)
Author
Z.Y. Kalender
E. Stump
K. Hubenig
N.G. Holmes
Abstract

Instructional physics labs offer students unique opportunities to develop an understanding of experimentation. By transforming labs to be more open ended and experimentation focused, instructors can better support student agency and choice. In this study, we examine students’ overall sense of and perceptions about agency in two experimentation-focused labs: one course primarily taken by physics majors and another course primarily taken by engineering majors. We compare the sense of and perceptions about agency between the different courses and between men and women in each course.

Journal
Physical Review Physics Education Research
Date Published
Funding Source
1836617
Group (Lab)
Natasha Holmes Group

Does filling-dependent band renormalization aid pairing in twisted bilayer graphene?

Cornell Affiliated Author(s)
Author
C. Lewandowski
S. Nadj-Perge
Debanjan Chowdhury
Abstract

Magic-angle twisted bilayer graphene (MATBG) exhibits a panoply of many-body phenomena that are intimately tied to the appearance of narrow and well-isolated electronic bands. The microscopic ingredients that are responsible for the complex experimental phenomenology include electron–electron (phonon) interactions and nontrivial Bloch wavefunctions associated with the narrow bands.

Journal
npj Quantum Materials
Date Published
Funding Source
DMR-1753306
1753306
GBMF1250
GBMF8682
Group (Lab)
Debanjan Chowdhury Group

Geometry of gene regulatory dynamics

Cornell Affiliated Author(s)
Author
D.A. Rand
A. Raju
M. Sáez
F. Corson
E.D. Siggia
Abstract

Embryonic development leads to the reproducible and ordered appearance of complexity from egg to adult. The successive differentiation of different cell types that elaborate this complexity results from the activity of gene networks and was likened by Waddington to a flow through a landscape in which valleys represent alternative fates. Geometric methods allow the formal representation of such landscapes and codify the types of behaviors that result from systems of differential equations.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Funding Source
PHY-1748958
R25GM067110
2919.02
FC001051
EP/P019811/1
2013131
ANR16-CE13-0003-02
Research Area

Importance of bulk excitations and coherent electron-photon-phonon scattering in photoemission from PbTe(111): Ab initio theory with experimental comparisons

Cornell Affiliated Author(s)
Author
J.K. Nangoi
S. Karkare
R. Sundararaman
H.A. Padmore
Tomas Arias
Abstract

This paper presents a fully ab initio many-body photoemission framework that includes coherent three-body electron-photon-phonon scattering to predict the transverse momentum distributions and the mean transverse energies (MTEs) of bulk photoelectrons from single-crystal photocathodes. The need to develop such a theory stems from the lack of studies that provide complete understanding of the underlying fundamental processes governing the transverse momentum distribution of photoelectrons emitted from single crystals.

Journal
Physical Review B
Date Published
Funding Source
PHY-1549132
DE-AC02-05CH11231
DE-SC0021092
KC0407-ALSJNT-I0013
Group (Lab)
Tomas Arias Group

Continuous Mott transition in semiconductor moiré superlattices

Author
T. Li
S. Jiang
L. Li
Y. Zhang
K. Kang
J. Zhu
K. Watanabe
T. Taniguchi
Debanjan Chowdhury
L. Fu
J. Shan
K.F. Mak
Abstract

The evolution of a Landau Fermi liquid into a non-magnetic Mott insulator with increasing electronic interactions is one of the most puzzling quantum phase transitions in physics1–6. The vicinity of the transition is believed to host exotic states of matter such as quantum spin liquids4–7, exciton condensates8 and unconventional superconductivity1. Semiconductor moiré materials realize a highly controllable Hubbard model simulator on a triangular lattice9–22, providing a unique opportunity to drive a metal–insulator transition (MIT) via continuous tuning of the electronic interactions.

Journal
Nature
Date Published
Funding Source
DMR-1807810
W911NF-17-1-0605
DMR-1719875
NNCI-1542081
JPMJCR15F3
Group (Lab)
Debanjan Chowdhury Group
Jie Shan Group
Kin Fai Mak Group

Computational synthesis of substrates by crystal cleavage

Cornell Affiliated Author(s)
Author
J.T. Paul
A. Galdi
C. Parzyck
K. Shen
J. Maxson
R.G. Hennig
Abstract

The discovery of substrate materials has been dominated by trial and error, opening the opportunity for a systematic search. We generate bonding networks for materials from the Materials Project and systematically break up to three bonds in the networks for three-dimensional crystals. Successful cleavage reduces the bonding network to two periodic dimensions. We identify 4693 symmetrically unique cleavage surfaces across 2133 bulk crystals, 4626 of which have a maximum Miller index of one.

Journal
npj Computational Materials
Date Published
Funding Source
DMR-1542776
DMS-1440415
OAC-1740251
PHY-1549132
Group (Lab)
Kyle Shen Group

Multivalued Inverse Design: Multiple Surface Geometries from One Flat Sheet

Cornell Affiliated Author(s)
Author
I. Griniasty
C. Mostajeran
Itai Cohen
Abstract

Designing flat sheets that can be made to deform into three-dimensional shapes is an area of intense research with applications in micromachines, soft robotics, and medical implants. Thus far, such sheets were designed to adopt a single target shape. Here, we show that through anisotropic deformation applied inhomogeneously throughout a sheet, it is possible to design a single sheet that can deform into multiple surface geometries upon different actuations. The key to our approach is development of an analytical method for solving this multivalued inverse problem.

Journal
Physical Review Letters
Date Published
Funding Source
1719875
DMR-1719875
EFMA-1935252
W911NF-18-1-0032
Group (Lab)
Itai Cohen Group

Emission of particles from a parametrically driven condensate in a one-dimensional lattice

Cornell Affiliated Author(s)
Author
L.Q. Lai
Y.B. Yu
E.J. Mueller
Abstract

Motivated by recent experiments, we calculate particle emission from a Bose-Einstein condensate trapped in a single deep well of a one-dimensional lattice when the interaction strength is modulated. In addition to pair emission, which has been widely studied, we observe single-particle emission. Within linear response, we are able to write closed-form expressions for the single-particle emission rates and reduce the pair emission rates to one-dimensional integrals.

Journal
Physical Review A
Date Published
Funding Source
PHY-2110250
201906130092
PHY-2110250

Glass phenomenology in the hard matrix model

Cornell Affiliated Author(s)
Author
J. Dong
V. Elser
G. Gyawali
K.Y. Jee
J. Kent-Dobias
A. Mandaiya
M. Renz
Y. Su
Abstract

We introduce a new toy model for the study of glasses: the hard-matrix model. This may be viewed as a single particle moving on SO(N), where there is a potential proportional to the one-norm of the matrix. The ground states of the model are 'crystals' where all matrix elements have the same magnitude. These are the Hadamard matrices when N is divisible by four. Just as finding the latter has challenged mathematicians, our model fails to find them upon cooling and instead shows all the behaviors that characterize physical glasses.

Journal
Journal of Statistical Mechanics: Theory and Experiment
Date Published
Group (Lab)
Veit Elser Group

Maximizing spin-orbit torque generated by the spin Hall effect of Pt

Cornell Affiliated Author(s)
Author
Lijun Zhu
Daniel Ralph
Robert Buhrman
Abstract

Efficient generation of spin-orbit torques is central for the exciting field of spin-orbitronics. Platinum, the archetypal spin Hall material, has the potential to be an outstanding provider for spin-orbit torques due to its giant spin Hall conductivity, low resistivity, high stabilities, and the ability to be compatible with CMOS circuits. However, pure clean-limit Pt with low resistivity still provides a low damping-like spin-orbit torque efficiency, which limits its practical applications.

Journal
AIP Publishing
Date Published
Funding Source
N00014-19-1-2143