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Publications

Role of correlations in determining the Van Hove strain in Sr2 RuO4

Cornell Affiliated Author(s)
Author
Mark Barber
Frank Lechermann
Sergey Streltsov
Sergey Skornyakov
Sayak Ghosh
B. Ramshaw
Naoki Kikugawa
Dmitry Sokolov
Andrew Mackenzie
Clifford Hicks
I. Mazin
Abstract

Uniaxial pressure applied along a Ru-O-Ru bond direction induces an elliptical distortion of the largest Fermi surface of Sr2RuO4, eventually causing a Fermi surface topological transition, also known as a Lifshitz transition, into an open Fermi surface. There are various anomalies in low-temperature properties associated with this transition, including maxima in the superconducting critical temperature and in resistivity.

Journal
Physical Review B
Date Published
Funding Source
1752784
JP18K04715
02.
AAAA-A18-118020190095-4
Group (Lab)
Brad Ramshaw Group

Imaging uncompensated moments and exchange-biased emergent ferromagnetism in FeRh thin films

Cornell Affiliated Author(s)
Author
Isaiah Gray
Gregory Stiehl
John Heron
Antonio Mei
Darrell Schlom
Ramamoorthy Ramesh
Daniel Ralph
Gregory Fuchs
Abstract

Uncompensated moments (UMs) in antiferromagnets are responsible for exchange bias in antiferromagnet/ ferromagnet heterostructures; however, they are difficult to directly detect because any signal they contribute is typically overwhelmed by the ferromagnetic layer. We use magnetothermal microscopy to image micron-scale uncompensated moments in thin films of FeRh, a room-temperature antiferromagnet that exhibits a first-order phase transition to a ferromagnetic (FM) state near 400 K.

Journal
American Physical Society (APS)
Date Published
Funding Source
1542081
1708499
1719875
1740136
SRC

Fractionalized pair density wave in the pseudogap phase of cuprate superconductors

Cornell Affiliated Author(s)
Author
D. Chakraborty
M. Grandadam
M.H. Hamidian
J.C.S. Davis
Y. Sidis
C. Pépin
Abstract

The mysterious pseudogap (PG) phase of cuprate superconductors has been the subject of intense investigation over the last 30 years, but without a clear agreement about its origin. Owing to a recent observation in Raman spectroscopy, of a precursor in the charge channel, on top of the well known fact of a precursor in the superconducting channel, we present here a novel idea: The PG is formed through a Higgs mechanism, where two kinds of preformed pairs, in the particle-particle and particle-hole channels, become entangled through a freezing of their global phase.

Journal
Physical Review B
Date Published
Group (Lab)
J.C. Seamus Davis Group

Magnetic handshake materials as a scale-invariant platform for programmed self-assembly

Cornell Affiliated Author(s)
Author
R. Niu
C.X. Du
E. Esposito
J. Ng
M.P. Brenner
P.L. McEuen
Itai Cohen
Abstract

Programmable self-assembly of smart, digital, and structurally complex materials from simple components at size scales from the macro to the nano remains a long-standing goal of material science. Here, we introduce a platform based on magnetic encoding of information to drive programmable self-assembly that works across length scales. Our building blocks consist of panels with different patterns of magnetic dipoles that are capable of specific binding.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Funding Source
DMR-1435829
N00014-17-1-3029
1435829
ARL FA8650-19-1-7914
DMR-1719875
Research Area
Group (Lab)
Itai Cohen Group
Paul McEuen Group

A New method for computing particle collisions in Navier-Stokes flows

Cornell Affiliated Author(s)
Author
A.E. Yacoubi
S. Xu
Z.J. Wang
Abstract

Particle collisions in fluids are ubiquitous, but to compute the collision dynamics in a Navier-Stokes flow remains challenging. In addition to capturing the two-way coupling between the fluid and the particles, a key difficulty is to resolve the collision dynamics mediated by the flow. The gap between particles during collision is minuscule. This introduces a small length scale which needs to be resolved simultaneously with the flow at the large scale.

Journal
Journal of Computational Physics
Date Published
Funding Source
1320317
Group (Lab)
Z. Jane Wang Group

Dirac fermions and possible weak antilocalization in LaCuSb2

Cornell Affiliated Author(s)
Author
J. Chamorro
A. Topp
Y. Fang
M.J. Winiarski
C.R. Ast
M. Krivenkov
A. Varykhalov
B.J. Ramshaw
L.M. Schoop
T.M. McQueen
Abstract

Layered heavy-metal square-lattice compounds have recently emerged as potential Dirac fermion materials due to bonding within those sublattices. We report quantum transport and spectroscopic data on the layered Sb square-lattice material LaCuSb2. Linearly dispersing band crossings, necessary to generate Dirac fermions, are experimentally observed in the electronic band structure observed using angle-resolved photoemission spectroscopy, along with a quasi-two-dimensional Fermi surface.

Journal
APL Materials
Date Published
Funding Source
1420541
1752784
DMR-1420541
Group (Lab)
Brad Ramshaw Group

Materials Relevant to Realizing a Field-Effect Transistor Based on Spin–Orbit Torques

Cornell Affiliated Author(s)
Author
Phillip Dang
Zexuan Zhang
Joseph Casamento
Xiang Li
Jashan Singhal
Darrell Schlom
Daniel Ralph
Huili Xing
Debdeep Jena
Abstract

Spin-orbit torque (SOT) is a promising mechanism for writing magnetic memories, while field-effect transistors (FETs) are the gold-standard device for logic operation. The spin-orbit torque field-effect transistor (SOTFET) is a proposed device that couples an SOT-controlled ferromagnet to a semiconducting transistor channel via the transduction in a magnetoelectric multiferroic (MF). This allows the SOTFET to operate as both a memory and a logic device, but its realization depends on the choice of appropriate materials.

Journal
Institute of Electrical and Electronics Engineers (IEEE)
Date Published
Funding Source
E2CDA 1740286
NewLAW EFRI 1741694
DGE-1650441
1740286
1741694

Modeling and Circuit Design of Associative Memories With Spin–Orbit Torque FETs

Cornell Affiliated Author(s)
Author
Olalekan Afuye
Xiang Li
Felicia Guo
Debdeep Jena
Daniel Ralph
Alyosha Molnar
Huili Xing
Alyssa Apsel
Abstract

This article introduces a circuits model for a proposed spin-based device called a spin-orbit torque field-effect transistor (SOTFET) that can operate as a nonvolatile memory and logic device. The SOTFET utilizes an FET structure with a ferromagnetic-multiferroic (MF) gate-stack that enables read/compute and write functions to be isolated. This is achieved by a combination of a ferromagnetic layer that is programmable via spin-orbit torque coupled to an MF layer that also couples into the gate of a traditional FET.

Journal
Institute of Electrical and Electronics Engineers (IEEE)
Date Published
Funding Source
1740286
ECCS 1740286
2758.001
2758.002

Pressure-controlled interlayer magnetism in atomically thin CrI3

Cornell Affiliated Author(s)
Author
T. Li
S. Jiang
N. Sivadas
Z. Wang
Y. Xu
D. Weber
J.E. Goldberger
K. Watanabe
T. Taniguchi
C.J. Fennie
Fai Mak
J. Shan
Abstract

Stacking order can influence the physical properties of two-dimensional van der Waals materials1,2. Here we applied hydrostatic pressure up to 2 GPa to modify the stacking order in the van der Waals magnetic insulator CrI3. We observed an irreversible interlayer antiferromagnetic-to-ferromagnetic transition in atomically thin CrI3 by magnetic circular dichroism and electron tunnelling measurements. The effect was accompanied by a monoclinic-to-rhombohedral stacking-order change characterized by polarized Raman spectroscopy.

Journal
Nature Materials
Date Published
Funding Source
1719875
N00014-18-1-2368
W911NF-17-1-0605
DMR-1719875
DMR-1420451
WE6480/1
JPMJCR15F3
Group (Lab)
Jie Shan Group
Kin Fai Mak Group