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Publications

Teaching critical thinking

Cornell Affiliated Author(s)
Author
N.G. Holmes
C.E. Wieman
D.A. Bonn
Abstract

The ability to make decisions based on data, with its inherent uncertainties and variability, is a complex and vital skill in the modern world. The need for such quantitative critical thinking occurs in many different contexts, and although it is an important goal of education, that goal is seldom being achieved. We argue that the key element for developing this ability is repeated practice in making decisions based on data, with feedback on those decisions.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published

Hierarchical spin-orbital polarization of a giant Rashba system

Cornell Affiliated Author(s)
Author
L. Bawden
J.M. Riley
C.H. Kim
R. Sankar
E.J. Monkman
D.E. Shai
H.I. Wei
E.B. Lochocki
J.W. Wells
W. Meevasana
T.K. Kim
M. Hoesch
Y. Ohtsubo
P. Le Fèvre
C.J. Fennie
K.M. Shen
F. Chou
P.D.C. King
Abstract

The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization.

Journal
Science Advances
Date Published
Funding Source
0847385
0903653
1056441
1120296
1144153
N00014-12-1-0791
DGE-0903653
SI9427
EP/G03673X/1
EP/I031014/1
EP/L505079/1
EP/M023427/1
26887024
RSA5680052
MOST-102-2119-M-002-004
DGE-1144153
DMR-0847385
DMR-1056441
DMR-1120296
Group (Lab)
Kyle Shen Group

Disorder-induced power-law response of a superconducting vortex on a plane

Cornell Affiliated Author(s)
Author
N. Shapira
Y. Lamhot
O. Shpielberg
Y. Kafri
B.J. Ramshaw
D.A. Bonn
R. Liang
W.N. Hardy
O.M. Auslaender
Abstract

We report drive-response experiments on individual superconducting vortices on a plane, a realization for a (1+1)-dimensional directed polymer in random media. For this we use magnetic force microscopy to image and manipulate individual vortices trapped on a twin boundary in YBa2Cu3O7-δ near optimal doping. We find that when we drag a vortex with the magnetic tip, it moves in a series of jumps. As theory suggests, the jump-size distribution does not depend on the applied force and is consistent with power-law behavior.

Journal
Physical Review B - Condensed Matter and Materials Physics
Date Published
Funding Source
1897/14
268294
Group (Lab)
Brad Ramshaw Group

Exotic Self-trapped States of an Electron in Superfluid Helium

Cornell Affiliated Author(s)
Author
V. Elser
Abstract

We explore the possibility that the fast and exotic negative ions in superfluid helium are electrons bound to quantized vortex structures, the simplest being a ring. In the states we consider, the electron energy is only slightly below the conduction band minimum of bulk helium. To support our proposal, we present two calculations. In the first, we show that the electron pressure on the vortex core is insufficient to cavitate the helium and form an electron bubble.

Journal
Journal of Low Temperature Physics
Date Published
Group (Lab)
Veit Elser Group

Mapping the conformational landscape of a dynamic enzyme by multitemperature and XFEL crystallography

Cornell Affiliated Author(s)
Author
D.A. Keedy
L.R. Kenner
M. Warkentin
R.A. Woldeyes
J.B. Hopkins
M.C. Thompson
A.S. Brewster
A.H.V. Benschoten
E.L. Baxter
M. Uervirojnangkoorn
S.E. McPhillips
J. Song
R. Alonso-Mori
J.M. Holton
W.I. Weis
A.T. Brunger
S.M. Soltis
H. Lemke
A. Gonzalez
N.K. Sauter
A.E. Cohen
H. van den Bedem
R.E. Thorne
J.S. Fraser
Abstract

Determining the interconverting conformations of dynamic proteins in atomic detail is a major challenge for structural biology. Conformational heterogeneity in the active site of the dynamic enzyme cyclophilin A (CypA) has been previously linked to its catalytic function, but the extent to which the different conformations of these residues are correlated is unclear. Here we compare the conformational ensembles of CypA by multitemperature synchrotron crystallography and fixed-target X-ray free-electron laser (XFEL) crystallography.

Journal
eLife
Date Published
Research Area
Group (Lab)
Robert Thorne Group

Measuring microscale strain fields in articular cartilage during rapid impact reveals thresholds for chondrocyte death and a protective role for the superficial layer

Cornell Affiliated Author(s)
Author
L.R. Bartell
L.A. Fortier
L.J. Bonassar
Itai Cohen
Abstract

Articular cartilage is a heterogeneous soft tissue that dissipates and distributes loads in mammalian joints. Though robust, cartilage is susceptible to damage from loading at high rates or magnitudes. Such injurious loads have been implicated in degenerative changes, including chronic osteoarthritis (OA), which remains a leading cause of disability in developed nations. Despite decades of research, mechanisms of OA initiation after trauma remain poorly understood.

Journal
Journal of Biomechanics
Date Published
Funding Source
DMR-1056662
R21AR062677
Research Area
Group (Lab)
Itai Cohen Group

Quantitative comparisons to promote inquiry in the introductory physics lab

Cornell Affiliated Author(s)
Author
N.G. Holmes
D.A. Bonn
Abstract

In a recent report, the American Association of Physics Teachers has developed an updated set of recommendations for curriculum of undergraduate physics labs. This document focuses on six major themes: constructing knowledge, modeling, designing experiments, developing technical and practical laboratory skills, analyzing and visualizing data, and communicating physics. These themes all tie together as a set of practical skills in scientific measurement, analysis, and experimentation.

Journal
Physics Teacher
Date Published

Strongly enhanced charge-density-wave order in monolayer NbSe 2

Cornell Affiliated Author(s)
Author
X. Xi
L. Zhao
Z. Wang
H. Berger
L. Forró
J. Shan
K.F. Mak
Abstract

Two-dimensional materials possess very different properties from their bulk counterparts. While changes in single-particle electronic properties have been investigated extensively, modifications in the many-body collective phenomena in the exact two-dimensional limit remain relatively unexplored. Here, we report a combined optical and electrical transport study on the many-body collective-order phase diagram of NbSe 2 down to a thickness of one monolayer. Both the charge density wave and the superconducting phase have been observed down to the monolayer limit.

Journal
Nature Nanotechnology
Date Published
Funding Source
DMR-1420451
1106225
1410407
DMR-1106225
DMR-1410407
DESC0012635
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Dependence of the efficiency of spin Hall torque on the transparency of Pt/ferromagnetic layer interfaces

Cornell Affiliated Author(s)
Author
Chi-Feng Pai
Yongxi Ou
Luis Vilela-Leão
D. Ralph
Robert Buhrman
Abstract

We report that spin current transport across Pt/ferromagnet (FM) interfaces as measured by the spin torques exerted on the FM is strongly dependent on the type and the thickness of the FM layer and on post-deposition processing protocols. By employing both harmonic voltage measurements and spin-torque ferromagnetic resonance measurements, we find that the efficiency of the Pt spin Hall effect in exerting a dampinglike spin torque on the FM corresponds to an effective spin Hall ratio ranging from <0.05 to >0.10 under different interfacial conditions.

Journal
American Physical Society (APS)
Date Published