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Publications

Symmetry Control of Unconventional Spin–Orbit Torques in IrO2

Cornell Affiliated Author(s)
Author
Michael Patton
Gautam Gurung
Ding-Fu Shao
Gahee Noh
Joseph Mittelstaedt
Marcel Mazur
Jong-Woo Kim
Philip Ryan
Evgeny Tsymbal
Si-Young Choi
Daniel Ralph
Mark Rzchowski
Tianxiang Nan
Chang-Beom Eom
Abstract

Abstract Spin?orbit torques generated by a spin current are key to magnetic switching in spintronic applications. The polarization of the spin current dictates the direction of switching required for energy-efficient devices. Conventionally, the polarizations of these spin currents are restricted to be along a certain direction due to the symmetry of the material allowing only for efficient in-plane magnetic switching.

Journal
Advanced Materials
Date Published
Funding Source
ONR N00014-20-1-2844
DMR-1720415
GBMF9065
DE-FG02-06ER46327
DE-SC0017671
OIA-2044049
2020R1A4A1018935

Superconductivity, Charge Density Wave, and Supersolidity in Flat Bands with a Tunable Quantum Metric

Cornell Affiliated Author(s)
Author
J.S. Hofmann
E. Berg
D. Chowdhury
Abstract

Predicting the fate of an interacting system in the limit where the electronic bandwidth is quenched is often highly nontrivial. The complex interplay between interactions and quantum fluctuations driven by the band geometry can drive competition between various ground states, such as charge density wave order and superconductivity. In this work, we study an electronic model of topologically trivial flat bands with a continuously tunable Fubini-Study metric in the presence of on-site attraction and nearest-neighbor repulsion, using numerically exact quantum Monte Carlo simulations.

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

Transferring orbital angular momentum to an electron beam reveals toroidal and chiral order

Cornell Affiliated Author(s)
Author
K.X. Nguyen
Y. Jiang
M.C. Cao
P. Purohit
A.K. Yadav
P. García-Fernández
M.W. Tate
C.S. Chang
P. Aguado-Puente
J. Íñiguez
F. Gomez-Ortiz
S.M. Gruner
J. Junquera
L.W. Martin
R. Ramesh
D.A. Muller
Abstract

Orbital angular momentum (OAM) and torque transfer play central roles in a wide range of magnetic textures and devices including skyrmions and spin-torque electronics. Analogous topological structures are now also being explored in ferroelectrics, including polarization vortex arrays in ferroelectric/dielectric superlattices. Unlike magnetic toroidal order, electric toroidal order does not couple directly to linear external fields.

Journal
Physical Review B
Date Published
Funding Source
DMR-1719875
DE-SC0002334
DE-FG02-10ER46693
FA9550-16-1-0031
PGC2018-096955-B
C15/MS/10458889
Group (Lab)
Sol M. Gruner Group

A geometrical perspective on development

Cornell Affiliated Author(s)
Author
A. Raju
E.D. Siggia
Abstract

Cell fate decisions emerge as a consequence of a complex set of gene regulatory networks. Models of these networks are known to have more parameters than data can determine. Recent work, inspired by Waddington's metaphor of a landscape, has instead tried to understand the geometry of gene regulatory networks. Here, we describe recent results on the appropriate mathematical framework for constructing these landscapes. This allows the construction of minimally parameterized models consistent with cell behavior.

Journal
Development Growth and Differentiation
Date Published
Funding Source
2013131
Research Area

Interplay of hidden orbital order and superconductivity in CeCoIn5

Cornell Affiliated Author(s)
Author
W. Chen
Neerup Breiø
F. Massee
M.P. Allan
C. Petrovic
J.C.S. Davis
P.J. Hirschfeld
B.M. Andersen
A. Kreisel
Abstract

Visualizing atomic-orbital degrees of freedom is a frontier challenge in scanned microscopy. Some types of orbital order are virtually imperceptible to normal scattering techniques because they do not reduce the overall crystal lattice symmetry. A good example is dxz/dyz (π,π) orbital order in tetragonal lattices. For enhanced detectability, here we consider the quasiparticle scattering interference (QPI) signature of such (π,π) orbital order in both normal and superconducting phases.

Journal
Nature Communications
Date Published
Funding Source
DE-FG02-05ER46236
GBMF9457
DE-SC0012704
R64897
DLV-788932
SFI 17/RP/5445
Group (Lab)
J.C. Seamus Davis Group

Calorimetric measurement of nuclear spin-lattice relaxation rate in metals

Cornell Affiliated Author(s)
Author
A. Khansili
A. Bangura
R. McDonald
B. Ramshaw
A. Rydh
A. Shekhter
Abstract

The quasiparticle density of states in correlated and quantum-critical metals directly probes the effect of electronic correlations on the Fermi surface. Measurements of the nuclear spin-lattice relaxation rate provide one such experimental probe of quasiparticle mass through the electronic density of states. By far the most common way of accessing the spin-lattice relaxation rate is via nuclear magnetic resonance and nuclear quadrupole resonance experiments, which require resonant excitation of nuclear spin transitions.

Journal
Physical Review B
Date Published
Group (Lab)
Brad Ramshaw Group

Etoposide promotes DNA loop trapping and barrier formation by topoisomerase II

Cornell Affiliated Author(s)
Author
T.T. Le
M. Wu
J.H. Lee
N. Bhatt
J.T. Inman
J.M. Berger
M.D. Wang
Abstract

Etoposide is a broadly employed chemotherapeutic and eukaryotic topoisomerase II poison that stabilizes cleaved DNA intermediates to promote DNA breakage and cytotoxicity. How etoposide perturbs topoisomerase dynamics is not known. Here we investigated the action of etoposide on yeast topoisomerase II, human topoisomerase IIα and human topoisomerase IIβ using several sensitive single-molecule detection methods. Unexpectedly, we found that etoposide induces topoisomerase to trap DNA loops, compacting DNA and restructuring DNA topology.

Journal
Nature Chemical Biology
Date Published
Funding Source
R01-CA077373
R01GM136894
R35-CA263778
T32GM008267
Research Area
Group (Lab)
Michelle Wang Group

Graph gauge theory of mobile non-Abelian anyons in a qubit stabilizer code

Cornell Affiliated Author(s)
Author
Y.D. Lensky
K. Kechedzhi
I. Aleiner
Eun-Ah Kim
Abstract

Stabilizer codes allow for non-local encoding and processing of quantum information. Deformations of stabilizer surface codes introduce new and non-trivial geometry, in particular leading to emergence of long sought after objects known as projective Ising non-Abelian anyons. Braiding of such anyons is a key ingredient of topological quantum computation. We suggest a simple and systematic approach to construct effective unitary protocols for braiding, manipulation and readout of non-Abelian anyons and preparation of their entangled states.

Journal
Annals of Physics
Date Published
Funding Source
920665
OAC-2118310
PHY-160761
Group (Lab)

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
Funding Source
2020-1-FI01-KA226-HE-092531
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
Funding Source
CMMI 1927197
CMMI 2129776
DMR 1807602
DMR-1719875
Group (Lab)
Itai Cohen Group