scholarly journals Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn2Au and Permalloy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. P. Bommanaboyena ◽  
D. Backes ◽  
L. S. I. Veiga ◽  
S. S. Dhesi ◽  
Y. R. Niu ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Ferromagnetic Layer ◽  
High Resolution Electron Microscopy ◽  
Spin Orbit ◽  
Domain Pattern ◽  
Microscopy Imaging ◽  
Ferromagnetic Domain ◽  
Resolution Electron ◽  
Strong Exchange ◽  
Novel Devices

AbstractIn antiferromagnetic spintronics, the read-out of the staggered magnetization or Néel vector is the key obstacle to harnessing the ultra-fast dynamics and stability of antiferromagnets for novel devices. Here, we demonstrate strong exchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits Néel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows us to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are only slightly diminished. We show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. Conversely, alignment of the Permalloy magnetization reorients the Mn2Au Néel vector, an effect, which can be restricted to large magnetic fields by tuning the ferromagnetic layer thickness. To understand the origin of the strong coupling, we carry out high resolution electron microscopy imaging and we find that our growth yields an interface with a well-defined morphology that leads to the strong exchange coupling.

A Grease for Domain Walls Motion in HfO2-based Ferroelectrics

2021 ◽  
Author(s):  
Alireza Kashir ◽  
Mehrdad Ghiasabadi Farahani ◽  
Jan Lancok ◽  
Hyunsang Hwang ◽  
Stanislav Kamba
Keyword(s):  
Thin Film ◽  
Domain Walls ◽  
Field Effect Transistors ◽  
Field Measurements ◽  
High Resolution Electron Microscopy ◽  
Polar Regions ◽  
Microscopy Imaging ◽  
Resolution Electron ◽  
Ferroelectric Memories ◽  
Electric Field Measurements

Abstract A large coercive field EC of HfO2 based ferroelectric devices poses critical performance issues in their applications as ferroelectric memories and ferroelectric field effect transistors. A new design to reduce EC by fabricating nanolaminate Hf0.5Zr0.5O2 / ZrO2 (HZZ) thin films is used, followed by an ensuing annealing process at a comparatively high temperature 700 °C. High-resolution electron microscopy imaging detects tetragonal-like domain walls between orthorhombic polar regions. These walls decrease the potential barrier of polarization reversal in HfO2 based films compared to the conventional domain walls with a single non-polar spacer, causing about a 40% decrease in EC. Capacitance vs. electric field measurements on HZZ thin film uncovered a substantial increase of dielectric permittivity near the EC compared to the conventional Hf0.5Zr0.5O2 thin film, justifying the higher mobility of domain walls in the developed HZZ film. The tetragonal-like regions served as grease easing the movement of the domain wall and reducing EC

In or on? Location of noble metal particles on zeolite/binder support

1995 ◽  
Vol 53 ◽  
pp. 406-407
Author(s):  
G. E. Spinnler ◽  
J. Liu
Keyword(s):  
Electron Microscopy ◽  
Noble Metal ◽  
Analytical Techniques ◽  
Sample Surface ◽  
High Resolution Electron Microscopy ◽  
Metal Particles ◽  
State University ◽  
Microscopy Imaging ◽  
Transmission Imaging ◽  
Resolution Electron

The location of metal particles contained in a zeolite-alumina binder support matrix has been difficult to solve using analytical techniques including electron microscopy. Imaging of metal particles, particularly noble metal particles on relatively light matrices such as zeolites or aluminas, has been easily accomplished using high angle annular darkfield imaging (HAADF). Since transmission imaging provides a projection through the sample, location of the particles in the sample or on the surface is not obvious. Surfacesensitive signals such as secondary electrons (SE) and Auger electrons (AE) are necessary to detect particles on the sample surface. HAADF, SE, and AE imaging have been applied to locate noble metal particles in a zeolite support with an alpha alumina binder.The samples were analyzed in a UHV HB501S STEM (MIDAS, Microscope for Imaging and Diffraction Analysis of Surfaces) at the Center for High Resolution Electron Microscopy at Arizona State University. The samples were prepared by crushing and dry deposition on a holey carbon grid.

Structure Analysis of the Al-Inp (100) Interface

1987 ◽  
Vol 94 ◽  
Author(s):  
C. d'Anterroches ◽  
F. Houzay ◽  
M. Bensoussan
Keyword(s):  
Ultra Violet ◽  
High Resolution Electron Microscopy ◽  
High Energy ◽  
Epitaxial Relationship ◽  
Metallic Behavior ◽  
Covalent Bonds ◽  
Resolution Electron ◽  
Strong Exchange ◽  
Inp Surface

ABSTRACTHigh Resolution Electron Microscopy (HREM) images of the Al/InP interface were obtained from as-deposited films. The high purity Al films were deposited onto a clean (100) InP surface in a Molecular Beam Epitaxy (MBE) chamber. The in situ Reflection High Energy Electron Diffraction (RHEED) and Ultra-Violet Photoemission Spectroscopy (UPS) analyses showed a transformation of the InP surface during the Al deposition. The UPS data are interpreted as a strong exchange reaction between incoming Al and substrate In atoms. The In atoms are released and recover metallic behavior while Al atoms are involved in covalent bonds. At high coverages the RHEED analysis shows an epitaxial relationship in between Al and InP such as (110)Al//(100)InP with the two variants: [001]Al//[011]InP and [001]Al//[0–11]InP. The HREM images show that the interface AI/InP is perturbed and an intermediate layer is found. This layer appears to have the same crystal structure as InP indicated by extension of atomic planes from InP to the layer. However, the observed intensity, which corresponds to the mean potential of the forming atoms, is lighter than that of InP. Hence,out of these HREM and UPS results it is derived that an AlP or AlxIn1−xP compound is located at the Al/InP interface.

Nanostructuring and its Influence on the Thermoelectric Properties of the AgSbTe2-SnTe Quaternary System

2005 ◽  
Vol 886 ◽  
Author(s):  
Ioannis Androulakis ◽  
R. Pcionek ◽  
E. Quarez ◽  
O. Palchik ◽  
H. Kong ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Quaternary System ◽  
Rest Mass ◽  
Heterogeneous Systems ◽  
High Resolution Electron Microscopy ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
Microscopy Imaging ◽  
Resolution Electron ◽  
Power Response

ABSTRACTThe structural and thermoelectric properties of the AgSbTe2-SnTe quaternary system were studied. Powder averaged x-ray diffraction of Ag0.85SnSb1.15Te3 indicates a cubic NaCl-type structure in contrast with the single crystal refinements, which point towards tetragonal symmetry. Furthermore, high-resolution electron microscopy imaging revealed the system to be a nano-composite formed by thermodynamically driven compositional fluctuations rather than a solid solution as it was viewed in the past. The lattice thermal conductivity attains very low values, which is in accord with recent theories on thermal transport in heterogeneous systems. The charge transport properties of the system exhibit a rich physical behavior highlighted in the coexistence of an almost metallic carrier concentration (∼5×1021 cm−3) with a large thermoelectric power response of ∼160 μV/K at 650 K. This is attributed to a heavy hole effective mass that is almost six times that of the electron rest mass.

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