Skip to main content

Publications

Scanning SQUID microscopy in a cryogen-free dilution refrigerator

Cornell Affiliated Author(s)
Author
D. Low
G.M. Ferguson
A. Jarjour
B.T. Schaefer
M.D. Bachmann
P.J.W. Moll
K.C. Nowack
Abstract

We report a scanning superconducting quantum interference device (SQUID) microscope in a cryogen-free dilution refrigerator with a base temperature at the sample stage of at least 30 mK. The microscope is rigidly mounted to the mixing chamber plate to optimize thermal anchoring of the sample. The microscope housing fits into the bore of a superconducting vector magnet, and our design accommodates a large number of wires connecting the sample and sensor.

Journal
Review of Scientific Instruments
Date Published
Funding Source
715730
DE-SC0015947
DMR-1719875
MO 3077/1-1
Group (Lab)
Katja Nowack Group

Switching Current Density of Perpendicular Magnetization by Spin-Orbit Torque

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

In-plane current-induced strong dampinglike spin-orbit torque (SOT) can enable sub-nanosecond switching of thin-film nanomagnets for nonvolatile magnetic storage [1]. Enormous efforts have been made on developing energy-efficient, high-endurance, integration-friendly spin current generators (SCGs) [2], [3] that can provide high dampinglike SOT efficiency (xi DL j).

Conference Name
Spin-Orbit Torque
Date Published

Two-fold symmetric superconductivity in few-layer NbSe2

Cornell Affiliated Author(s)
Author
A. Hamill
B. Heischmidt
E. Sohn
D. Shaffer
K.-T. Tsai
X. Zhang
X. Xi
A. Suslov
H. Berger
L. Forró
F.J. Burnell
J. Shan
K.F. Mak
R.M. Fernandes
K. Wang
V.S. Pribiag
Abstract

The strong Ising spin–orbit coupling in certain two-dimensional transition metal dichalcogenides can profoundly affect the superconducting state in few-layer samples. For example, in NbSe2, this effect combines with the reduced dimensionality to stabilize the superconducting state against magnetic fields up to 35 T, and could lead to topological superconductivity. Here we report a two-fold rotational symmetry of the superconducting state in few-layer NbSe2 under in-plane external magnetic fields, in contrast to the three-fold symmetry of the lattice.

Journal
Nature Physics
Date Published
Funding Source
DMR-2011401
2011401
DMR-1420013
DMR-1644779
DMR-1807810
ECCS-1542202
N00014-18-1-2368
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Quantum oscillations and quasiparticle properties of thin film

Cornell Affiliated Author(s)
Author
Yawen Fang
Hari Nair
Ludi Miao
Berit Goodge
Nathaniel Schreiber
Jacob Ruf
Lena Kourkoutis
Kyle Shen
Darrell Schlom
B. Ramshaw
Abstract

We measure the Shubnikov-de Haas effect in thin-film grown on an substrate. We detect all three known Fermi surfaces and extract the Fermi surface volumes, cyclotron effective masses, and quantum lifetimes. We show that the electronic structure is nearly identical to that of single-crystal , and that the quasiparticle lifetime is consistent with the of comparably clean, single-crystal . Unlike single-crystal , where the quantum and transport lifetimes are roughly equal, we find that the transport lifetime is times longer than the quantum lifetime.

Journal
Physical Review B
Date Published
Funding Source
DMR-1709255
DGE-1650441
DMR-1539918
1429155
DMR-1644779
DMR-1752784
NNCI-2025233
FA9550-15-1-0474
GBMF3850
GBMF9073
DMR-1719875
Group (Lab)
Brad Ramshaw Group
Kyle Shen Group

Linear-in temperature resistivity from an isotropic Planckian scattering rate

Cornell Affiliated Author(s)
Author
Gael Grissonnanche
Yawen Fang
Anaëlle Legros
Simon Verret
Francis Laliberté
C. Collignon
Jianshi Zhou
David Graf
Paul Goddard
Louis Taillefer
B. Ramshaw
Abstract

A variety of ‘strange metals’ exhibit resistivity that decreases linearly with temperature as the temperature decreases to zero1–3, in contrast to conventional metals where resistivity decreases quadratically with temperature. This linear-in-temperature resistivity has been attributed to charge carriers scattering at a rate given by ħ/τ = αkBT, where α is a constant of order unity, ħ is the Planck constant and kB is the Boltzmann constant.

Journal
Nature
Date Published
Funding Source
DMR-1644779
MRSEC DMR-1720595
DMR-1752784
GBMF5306
681260
123817
Group (Lab)
Brad Ramshaw Group

Patternable Mesoporous Thin Film Quantum Materials via Block Copolymer Self-Assembly: An Emergent Technology?

Cornell Affiliated Author(s)
Author
F. Yu
R.P. Thedford
K.R. Hedderick
G. Freychet
M. Zhernenkov
L.A. Estroff
K.C. Nowack
Sol Gruner
U.B. Wiesner
Abstract

Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing.

Journal
ACS Applied Materials and Interfaces
Date Published
Funding Source
DMR-1719875
NNCI-2025233
DE-SC0010560
CHE-1531632
DE-SC0012704
DGE-1650441
Group (Lab)
Katja Nowack Group
Sol M. Gruner Group

Identification of Non-Fermi Liquid Physics in a Quantum Critical Metal via Quantum Loop Topography

Cornell Affiliated Author(s)
Author
G. Driskell
S. Lederer
C. Bauer
S. Trebst
Eun-Ah Kim
Abstract

Non-Fermi liquid physics is ubiquitous in strongly correlated metals, manifesting itself in anomalous transport properties, such as a T-linear resistivity in experiments. However, its theoretical understanding in terms of microscopic models is lacking, despite decades of conceptual work and attempted numerical simulations.

Journal
Physical Review Letters
Date Published
Group (Lab)

Magic continuum in a twisted bilayer square lattice with staggered flux

Cornell Affiliated Author(s)
Author
Zhu-Xi Luo
Cenke Xu
Chao-Ming Jian
Abstract

We derive the general continuum model for a bilayer system of staggered-flux square lattices, with arbitrary elastic deformation in each layer. Applying this general continuum model to the case where the two layers are rigidly rotated relative to each other by a small angle, we obtain the band structure of the twisted bilayer staggered-flux square lattice. We show that this band structure exhibits a magic continuum in the sense that an exponential reduction of the Dirac velocity and bandwidths occurs in a large parameter regime.

Journal
Physical Review B
Date Published
Funding Source
DMR-1920434
Group (Lab)
Chao-Ming Jian Group

Orbital optimization in selected configuration interaction methods

Cornell Affiliated Author(s)
Author
Yuan Yao
C. Umrigar
Abstract

We study several approaches to orbital optimization in selected configuration interaction (SCI) plus perturbation theory methods and test them on the ground and excited states of three molecules using the semistochastic heat-bath configuration interaction method. We discuss the ways in which the orbital optimization problem in SCI resembles and differs from that in complete active space self-consistent field.

Journal
Journal of Chemical Theory and Computation
Date Published
Funding Source
ACI-1445606
ACI-1547580
1445606
FA9550-18-1-0095
Group (Lab)
Cyrus Umrigar Group

Torsional Stiffness of Extended and Plectonemic DNA

Cornell Affiliated Author(s)
Author
X. Gao
Y. Hong
F. Ye
J.T. Inman
M.D. Wang
Abstract

DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression. However, direct measurements of these parameters are experimentally challenging. Here, we present a constant-extension method integrated into an angular optical trap to directly measure torque during DNA supercoiling. We measured the twist persistence length of extended DNA to be 22 nm under an extremely low force (∼0.02 pN) and the twist persistence length of plectonemic DNA to be 24 nm.

Journal
Physical Review Letters
Date Published
Research Area
Group (Lab)
Michelle Wang Group