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Publications

Impact of traditional physics lab instruction on students’ critical thinking skills in a Finnish context

Cornell Affiliated Author(s)
Author
P. Pirinen
A. Lehtinen
N.G. Holmes
Abstract

Recent studies have given incentives to physics departments around the world to revise the learning goals of their lab courses to emphasize experimentation skills over reinforcing lecture content. Evaluation instruments have been developed to measure the achievement of learning goals, and one such instrument is the Physics Lab Inventory of Critical thinking (PLIC). The PLIC measures respondents’ ability to evaluate models, evaluate methods, and to suggest the next steps for an investigation.

Journal
European Journal of Physics
Date Published
Group (Lab)
Natasha Holmes Group

Instabilities induced by mechanical loading determine the viability of chondrocytes grown on porous scaffolds

Cornell Affiliated Author(s)
Author
B. Kim
N. Bouklas
Itai Cohen
L.J. Bonassar
Abstract

Tissue-engineered cartilage constructs have shown promise to treat focal cartilage defects in multiple clinical studies. Notably, products in clinical use or in late-stage clinical trials often utilize porous collagen scaffolds to provide mechanical support and attachment sites for chondrocytes. Under loading, both the local mechanical responses of collagen scaffolds and the corresponding cellular outcomes are poorly understood, despite their wide use.

Journal
Journal of Biomechanics
Date Published
Group (Lab)
Itai Cohen Group

Non-equilibrium ordering of liquid crystalline (LC) films driven by external gradients in surfactant concentration

Cornell Affiliated Author(s)
Author
S. Maiti
S. Roh
Itai Cohen
N.L. Abbott
Abstract

Hypothesis: Gradients in the concentration of amphiphiles play an important role in many non-equilibrium processes involving complex fluids. Here we explore if non-equilibrium interfacial behaviors of thermotropic (oily) liquid crystals (LCs) can amplify microscopic gradients in surfactant concentration into macroscopic optical signals. Experiments: We use a milli-fluidic system to generate gradients in aqueous sodium dodecyl sulfate (SDS) concentration and optically quantify the dynamic ordering of micrometer-thick nematic LC films that contact the gradients.

Journal
Journal of Colloid and Interface Science
Date Published
Group (Lab)
Itai Cohen Group

Switchable moiré potentials in ferroelectric WTe2/WSe2 superlattices

Cornell Affiliated Author(s)
Author
K. Kang
W. Zhao
Y. Zeng
K. Watanabe
T. Taniguchi
J. Shan
K.F. Mak
Abstract

Moiré materials with superlattice periodicity many times the atomic length scale have shown strong electronic correlations and band topology with unprecedented tunability. Non-volatile control of the moiré potentials could allow on-demand switching of superlattice effects but has remained challenging to achieve. Here we demonstrate the switching of the correlated and moiré band insulating states, and the associated nonlinear anomalous Hall effect, by the ferroelectric effect.

Journal
Nature Nanotechnology
Date Published
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

A puzzling insensitivity of magnon spin diffusion to the presence of 180-degree domain walls

Cornell Affiliated Author(s)
Author
Ruofan Li
Lauren Riddiford
Yahong Chai
Minyi Dai
Hai Zhong
Bo Li
Peng Li
Di Yi
Yuejie Zhang
David Broadway
Adrien Dubois
Patrick Maletinsky
Jiamian Hu
Yuri Suzuki
Daniel Ralph
Tianxiang Nan
Abstract

We present room-temperature measurements of magnon spin diffusion in epitaxial ferrimagnetic insulator MgAl0.5Fe1.5O4 (MAFO) thin films near zero applied magnetic field where the sample forms a multi-domain state. Due to a weak uniaxial magnetic anisotropy, the domains are separated primarily by 180° domain walls.

Journal
Springer Science and Business Media LLC
Date Published
Group (Lab)
Dan C. Ralph Group

Domain-Dependent Surface Adhesion in Twisted Few-Layer Graphene: Platform for Moiré-Assisted Chemistry

Cornell Affiliated Author(s)
Author
V. Hsieh
D. Halbertal
N.R. Finney
Z. Zhu
E. Gerber
M. Pizzochero
E. Kucukbenli
G.R. Schleder
M. Angeli
K. Watanabe
T. Taniguchi
Eun-Ah Kim
E. Kaxiras
J. Hone
C.R. Dean
D.N. Basov
Abstract

Twisted van der Waals multilayers are widely regarded as a rich platform to access novel electronic phases thanks to the multiple degrees of freedom available for controlling their electronic and chemical properties. Here, we propose that the stacking domains that form naturally due to the relative twist between successive layers act as an additional ”knob” for controlling the behavior of these systems and report the emergence and engineering of stacking domain-dependent surface chemistry in twisted few-layer graphene.

Journal
Nano Letters
Date Published
Group (Lab)
Eun-Ah Kim Group

Superfluid response of an atomically thin gate-tuned van der Waals superconductor

Cornell Affiliated Author(s)
Author
A. Jarjour
G.M. Ferguson
B.T. Schaefer
M. Lee
Y.L. Loh
N. Trivedi
K.C. Nowack
Abstract

A growing number of two-dimensional superconductors are being discovered in the family of exfoliated van der Waals materials. Due to small sample volume, the superfluid response of these materials has not been characterized. Here, we use a local magnetic probe to directly measure this key property of the tunable, gate-induced superconducting state in MoS2. We find that the backgate changes the transition temperature non-monotonically whereas the superfluid stiffness at low temperature and the normal state conductivity monotonically increase.

Journal
Nature Communications
Date Published
Group (Lab)
Katja Nowack Group

Gate-tunable heavy fermions in a moiré Kondo lattice

Cornell Affiliated Author(s)
Author
W. Zhao
B. Shen
Z. Tao
Z. Han
K. Kang
K. Watanabe
T. Taniguchi
K.F. Mak
J. Shan
Abstract

The Kondo lattice—a matrix of local magnetic moments coupled through spin-exchange interactions to itinerant conduction electrons—is a prototype of strongly correlated quantum matter1–4. Usually, Kondo lattices are realized in intermetallic compounds containing lanthanide or actinide1,2. The complex electronic structure and limited tunability of both the electron density and exchange interactions in these bulk materials pose considerable challenges to studying Kondo lattice physics.

Journal
Nature
Date Published
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Strong variation of spin-orbit torques with relative spin relaxation rates in ferrimagnets

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

Spin-orbit torques (SOTs) have been widely understood as an interfacial transfer of spin that is independent of the bulk properties of the magnetic layer. Here, we report that SOTs acting on ferrimagnetic FexTb1-x layers decrease and vanish upon approaching the magnetic compensation point because the rate of spin transfer to the magnetization becomes much slower than the rate of spin relaxation into the crystal lattice due to spin-orbit scattering.

Journal
Springer Science and Business Media LLC
Date Published
Group (Lab)
Dan C. Ralph Group

Collective density fluctuations of strange metals with critical Fermi surfaces

Cornell Affiliated Author(s)
Author
X. Wang
Debanjan Chowdhury
Abstract

Recent spectroscopic measurements in a number of strongly correlated metals that exhibit non-Fermi-liquid-like properties have observed evidence of anomalous frequency and momentum-dependent charge-density fluctuations. Specifically, in the strange metallic regime of the cuprate superconductors, there is a featureless particle-hole continuum exhibiting unusual power laws, and experiments suggest that the plasmon mode decays into this continuum in a manner that is distinct from the expectations of conventional Fermi liquid theory.

Journal
Physical Review B
Date Published
Group (Lab)
Debanjan Chowdhury Group