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Publications

Cross Layer Design for the Predictive Assessment of Technology-Enabled Architectures

Cornell Affiliated Author(s)
Author
M. Niemier
X. Hu
L. Liu
M. Sharifi
I. O’Connor
D. Atienza
G. Ansaloni
C. Li
A. Khan
D. Ralph
Abstract

There is great interest in “end-to-end” analysis that captures how innovation at the materials, device, and/or archi-tectural levels will impact figures of merit at the application-level. However, there are numerous combinations of devices and architectures to study, and we must establish systematic ways to accurately explore and cull a vast design space. We aim to capture how innovations at the materials/device-level may ultimately impact figures of merit associated with both existing and emerging technologies that may be employed for either logic and/or memory.

Conference Name
2023 Design, Automation & Test in Europe Conference & Exhibition (DATE)
Date Published

Exchange Bias Between van der Waals Materials: Tilted Magnetic States and Field-Free Spin–Orbit-Torque Switching

Cornell Affiliated Author(s)
Author
T.M.J. Cham
R.J. Dorrian
X.S. Zhang
A.H. Dismukes
D.G. Chica
A.F. May
X. Roy
D.A. Muller
D.C. Ralph
Y.K. Luo
Abstract

Magnetic van der Waals heterostructures provide a unique platform to study magnetism and spintronics device concepts in the 2D limit. Here, studies of exchange bias from the van der Waals antiferromagnet CrSBr acting on the van der Waals ferromagnet Fe3GeTe2 (FGT) are reported. The orientation of the exchange bias is along the in-plane easy axis of CrSBr, perpendicular to the out-of-plane anisotropy of the FGT, inducing a strongly tilted magnetic configuration in the FGT.

Journal
Advanced Materials
Date Published

Thermally generated spin current in the topological insulator Bi2Se3

Cornell Affiliated Author(s)
Author
R. Jain
M. Stanley
A. Bose
A.R. Richardella
X.S. Zhang
T. Pillsbury
D.A. Muller
N. Samarth
D.C. Ralph
Abstract

We present measurements of thermally generated transverse spin currents in the topological insulator Bi2Se3, thereby completing measurements of interconversions among the full triad of thermal gradients, charge currents, and spin currents. We accomplish this by comparing the spin Nernst magneto-thermopower to the spin Hall magnetoresistance for bilayers of Bi2Se3/CoFeB. We find that Bi2Se3 does generate substantial thermally driven spin currents.

Journal
Science Advances
Date Published

Large spin–orbit torque in bismuthate-based heterostructures

Cornell Affiliated Author(s)
Author
A.L. Edgeton
I.A. Harris
N.G. Campbell
Y. Chai
M.M. Mazur
G. Gurung
X. Huang
S. Susarla
E.Y. Tsymbal
D.C. Ralph
T. Nan
M.S. Rzchowski
R. Ramesh
C.-B. Eom
Abstract

The wider application of spintronic devices requires the development of new material platforms that can efficiently be used to manipulate spin. Bismuthate-based superconductors are centrosymmetric systems that are generally thought to offer weak spin–orbit coupling. Here we report a large spin–orbit torque driven by spin polarization generated in heterostructures based on the bismuthate BaPb1−xBixO3 (which is in a non-superconducting state). Using spin-torque ferromagnetic resonance and d.c.

Journal
Nature Electronics
Date Published

Tuning the Curie temperature of a two-dimensional magnet/topological insulator heterostructure to above room temperature by epitaxial growth

Cornell Affiliated Author(s)
Author
Alexander Bishop
Xiyue Zhang
Katherine Robinson
Igor Lyalin
Ziling Li
Ryan Bailey-Crandell
Thow Cham
Shuyu Cheng
Yunqiu Luo
Daniel Ralph
David Muller
Roland Kawakami
Journal
PHYSICAL REVIEW MATERIALS
Date Published
Funding Source
FA9550-19-1-0390
DE-SC0016379
RX22-OSU-22-1
DMR-2011876
FA9550-19-1-0390
FA9550-19-1-0390
DMR-1719875
NNCI-2025233

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

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

Synthesis, Hole Doping, and Electrical Properties of a Semiconducting Azatriangulene-Based Covalent Organic Framework

Cornell Affiliated Author(s)
Author
David Burke
Raghunath Dasari
Vinod Sangwan
Alexander Oanta
Zoheb Hirani
Chloe Pelkowski
Yongjian Tang
Ruofan Li
Daniel Ralph
Mark Hersam
Stephen Barlow
Seth Marder
William Dichtel
Journal
Journal of the American Chemical Society
Date Published
Funding Source
W911NF-15-1-0447
DGE-1842165
NSF ECCS-2025633
NSF ECCS-2025633
NSF DMR-1720139
NSF DMR-1720139
DE-SC0017671
NNCI-2025233
DE-AC02-06CH11357
DE-SC0012704

A puzzling insensitivity of magnon spin diffusion to the presence of 180-degree domain walls

Cornell Affiliated Author(s)
Author
Ruofan Li
Lauren Riddiford
Yahong Chai
Minyi Dai
Hai Zhong
Bo Li
Peng Li
Di Yi
Yuejie Zhang
David Broadway
Adrien Dubois
Patrick Maletinsky
Jiamian Hu
Yuri Suzuki
Daniel Ralph
Tianxiang Nan
Abstract

We present room-temperature measurements of magnon spin diffusion in epitaxial ferrimagnetic insulator MgAl0.5Fe1.5O4 (MAFO) thin films near zero applied magnetic field where the sample forms a multi-domain state. Due to a weak uniaxial magnetic anisotropy, the domains are separated primarily by 180° domain walls.

Journal
Springer Science and Business Media LLC
Date Published
Funding Source
N00014-15-1-0045
ACI-1548562
CBET-2006028
NNCI-2025233
FA 9550-20-1-0293
DMR-1719875
52161135103
2021YFA0716500

Strong variation of spin-orbit torques with relative spin relaxation rates in ferrimagnets

Cornell Affiliated Author(s)
Author
Lijun Zhu
Daniel Ralph
Abstract

Spin-orbit torques (SOTs) have been widely understood as an interfacial transfer of spin that is independent of the bulk properties of the magnetic layer. Here, we report that SOTs acting on ferrimagnetic FexTb1-x layers decrease and vanish upon approaching the magnetic compensation point because the rate of spin transfer to the magnetization becomes much slower than the rate of spin relaxation into the crystal lattice due to spin-orbit scattering.

Journal
Springer Science and Business Media LLC
Date Published
Funding Source
NNCI-2025233
DMR-1719875
12274405
XDB44000000
2022YFA1200094