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Publications

Observation of suppressed viscosity in the normal state of 3He due to superfluid fluctuations

Author
Rakin Baten
Yefan Tian
Eric Smith
Erich Mueller
Jeevak Parpia
Abstract

AbstractEvidence of fluctuations in transport have long been predicted in 3He. They are expected to contribute only within 100μK of Tc and play a vital role in the theoretical modeling of ordering; they encode details about the Fermi liquid parameters, pairing symmetry, and scattering phase shifts. It is expected that they will be of crucial importance for transport probes of the topologically nontrivial features of superfluid 3He under strong confinement.

Journal
Nature Communications
Date Published
Group (Lab)
Jeevak Parpia Group

Sagnac interferometry for high-sensitivity optical measurements of spin-orbit torque

Author
Saba Karimeddiny
Thow Cham
Orion Smedley
Daniel Ralph
Yunqiu Luo
Abstract

Sagnac interferometry can provide a substantial improvement in signal-to-noise ratio compared to conventional magnetic imaging based on the magneto-optical Kerr effect. We show that this improvement is sufficient to allow quantitative measurements of current-induced magnetic deflections due to spin-orbit torque even in thin-film magnetic samples with perpendicular magnetic anisotropy, for which the Kerr rotation is second order in the magnetic deflection.

Journal
SCIENCE ADVANCES
Date Published
Funding Source
DMR1708499
DMR2104268
FA9550-19-1-0390
DMR-1719875
NNCI-2025233

Identifying structural and dynamic changes during the Biliverdin Reductase B catalytic cycle

Cornell Affiliated Author(s)
Author
E. Lee
M.J. McLeod
J.S. Redzic
B. Marcolin
R.E. Thorne
P. Agarwal
E.Z. Eisenmesser
Abstract

Biliverdin Reductase B (BLVRB) is an NADPH-dependent reductase that catalyzes the reduction of multiple substrates and is therefore considered a critical cellular redox regulator. In this study, we sought to address whether both structural and dynamics changes occur between different intermediates of the catalytic cycle and whether these were relegated to just the active site or the entirety of the enzyme.

Journal
Frontiers in Molecular Biosciences
Date Published
Funding Source
1807326
R01GM139892
DMR-1829070
GM-124166-01A1
Research Area
Group (Lab)
Robert Thorne Group

Electronic nematic order in the normal state of strontium ruthenate

Cornell Affiliated Author(s)
Author
R.S. Russell
H.P. Nair
K.M. Shen
D.G. Schlom
J.W. Harter
Abstract

Despite significant achievements in characterizing the properties of Sr2RuO4 over the last three decades, the precise nature of its electronic ground state is still unresolved. In this work, we provide a missing piece of the puzzle by uncovering evidence of electronic nematic order in the normal state of Sr2RuO4, revealed by ultrafast time-resolved optical dichroism measurements of uniaxially strained thin films. This nematic order, whose domains are aligned by the strain, spontaneously breaks the fourfold rotational symmetry of the crystal.

Journal
Physical Review B
Date Published
Funding Source
NNCI-2025233
FA9550-21-1-0168
GBMF3850
GBMF9073
DE-SC0019414
Group (Lab)
Kyle Shen Group

Quantum Criticality Under Decoherence or Weak Measurement

Cornell Affiliated Author(s)
Author
J.Y. Lee
C.-M. Jian
C. Xu
Abstract

Decoherence inevitably happens when a quantum state is exposed to its environment, which can affect quantum critical points (QCPs) in a nontrivial way. As was pointed out in the recent literature on (1+1)d conformal field theory (CFT) [Garratt et al. Measurements conspire nonlocally to restructure critical quantum states, arXiv:2207.09476 (2022)], the effect of weak measurement can be mathematically mapped to the problem of boundary CFT. In this work, we focus on the (2+1)d QCPs, whose boundary and defect effects have attracted enormous theoretical and numerical interests very recently.

Journal
PRX Quantum
Date Published
Group (Lab)
Chao-Ming Jian Group

Direct visualization of electronic transport in a quantum anomalous Hall insulator

Cornell Affiliated Author(s)
Author
G. Ferguson
Run Xiao
Anthony Richardella
David Low
Nitin Samarth
Katja Nowack
Abstract

A quantum anomalous Hall (QAH) insulator is characterized by quantized Hall and vanishing longitudinal resistances at zero magnetic field that are protected against local perturbations and independent of sample details. This insensitivity makes the microscopic details of the local current distribution inaccessible to global transport measurements. Accordingly, the current distributions that give rise to transport quantization are unknown. Here we use magnetic imaging to directly visualize the transport current in the QAH regime.

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

New perspectives on student reasoning about measurement uncertainty: More or better data

Cornell Affiliated Author(s)
Author
A. Schang
M. Dew
E.M. Stump
N.G. Holmes
G. Passante
Abstract

Uncertainty is an important and fundamental concept in physics education. Students are often first exposed to uncertainty in introductory labs, expand their knowledge across lab courses, and then are introduced to quantum mechanical uncertainty in upper-division courses. This study is part of a larger project evaluating student thinking about uncertainty across these contexts.

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

Loops in 4+1d topological phases

Cornell Affiliated Author(s)
Author
X. Chen
A. Dua
P.-S. Hsin
C.-M. Jian
W. Shirley
C. Xu
Abstract

2+1d topological phases are well characterized by the fusion rules and braiding/exchange statistics of fractional point excitations. In 4+1d, some topological phases contain only fractional loop excitations. What kind of loop statistics exist? We study the 4+1d gauge theory with 2-form Z2 gauge field (the loop-only toric code) and find that while braiding statistics between two different types of loops can be nontrivial, the self ‘exchange’ statistics are all trivial.

Journal
SciPost Physics
Date Published
Group (Lab)
Chao-Ming Jian Group

Jamming and unusual charge density fluctuations of strange metals

Cornell Affiliated Author(s)
Author
S.J. Thornton
D.B. Liarte
P. Abbamonte
J.P. Sethna
D. Chowdhury
Abstract

The strange metallic regime across a number of high-temperature superconducting materials presents numerous challenges to the classic theory of Fermi liquid metals. Recent measurements of the dynamical charge response of strange metals, including optimally doped cuprates, have revealed a broad, featureless continuum of excitations, extending over much of the Brillouin zone. The collective density oscillations of this strange metal decay into the continuum in a manner that is at odds with the expectations of Fermi liquid theory.

Journal
Nature Communications
Date Published
Group (Lab)
Debanjan Chowdhury Group
James Sethna Group