Epitaxial Co-Cu Superlattices

1991 ◽  
Vol 231 ◽  
Author(s):  
Elizabeth Schuler ◽  
Sezai Elagoz ◽  
William Vavra ◽  
Frank Lamelas ◽  
Hui David He ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Molecular Beam Epitaxy ◽  
Layer Thickness ◽  
Molecular Beam ◽  
Antiferromagnetic Coupling ◽  
Competing Interactions ◽  
X Ray ◽  
X Ray Scattering ◽  
Complex Spin

AbstractWe describe measurements on the magnetic properties of Co-Cu superlattices in which the Co layer thickness was fixed at 20 Å and the Cu thickness was varied from 4 Å to 24 Å. The samples were grown on Ge-buffered (110) GaAs by molecular beam epitaxy. X-ray scattering and in-situ RHEED indicate that the multilayers are oriented in the (111) direction with the Co layers stacked in an fcc arrangement. Our interest in this series of samples lies in their unusual hysteresis curves which show distinct transitions. We have found that the appearance of these transitions is directly related to the Cu thickness, indicating the presence of complex spin configurations as a consequence of competing interactions. The results are not consistent with a simple RKKY antiferromagnetic coupling.

A Study on the Growth of Cubic GaN Films Using an AlGaAs Buffer Layer Grown on GaAs (100) by Plasma-Assisted Molecular Beam Epitaxy

2000 ◽  
Vol 639 ◽  
Author(s):  
Ryuhei Kimura ◽  
Kiyoshi Takahashi ◽  
H. T. Grahn
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Molecular Beam ◽  
High Energy ◽  
Rf Plasma ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cubic Gan

ABSTRACTAn investigation of the growth mechanism for RF-plasma assisted molecular beam epitaxy of cubic GaN films using a nitrided AlGaAs buffer layer was carried out by in-situ reflection high energy electron diffraction (RHEED) and high resolution X-ray diffraction (HRXRD). It was found that hexagonal GaN nuclei grow on (1, 1, 1) facets during nitridation of the AlGaAs buffer layer, but a highly pure, cubic-phase GaN epilayer was grown on the nitrided AlGaAs buffer layer.

Extended X-ray Absorption Fine Structure Studies of GaN Epilayers Doped in situ with Er and Eu During Molecular Beam Epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
V. Katchkanov ◽  
J. F. W. Mosselmans ◽  
S. Dalmasso ◽  
K. P. O'Donnell ◽  
R. W. Martin ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Local Structure ◽  
Molecular Beam ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
The Eu

ABSTRACTThe local structure around Er and Eu atoms introduced into GaN epilayers was studied by means of Extended X-ray Absorption Fine Structure above the appropriate rare-earth X-ray absorption edge. The samples were doped in situ during growth by Molecular Beam Epitaxy. The formation of ErN clusters was found in samples with high average Er concentrations of 32±6% and 12.4±0.8%, estimated by Wavelength Dispersive X-ray analysis. When the average Er concentration is decreased to 6.0±0.2%, 1.6±0.2% and 0.17±0.02%, Er is found in localised clusters of ErGaN phase with high local Er content. Similar behaviour is observed for Eu-doped samples. For an average Eu concentration of 30.5±0.5% clusters of pure EuN occur. Decreasing the Eu concentration to 10.4±0.5% leads to EuGaN clusters with high local Eu content. However, for a sample with an Eu concentration of 14.2±0.5% clustering of Eu was not observed.

scholarly journals A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines

2012 ◽  
Vol 83 (10) ◽  
pp. 105112 ◽  
Author(s):  
T. Slobodskyy ◽  
P. Schroth ◽  
D. Grigoriev ◽  
A. A. Minkevich ◽  
D. Z. Hu ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray ◽  
Molecular Beam Epitaxy System ◽  
Synchrotron Beamlines

Influence of growth interruption on the formation of solid-state interfaces

2006 ◽  
Vol 21 (2) ◽  
pp. 122-124
Author(s):  
I. Busch ◽  
J. Stümpel ◽  
M. Krumrey
Keyword(s):  
Solid State ◽  
Molecular Beam Epitaxy ◽  
Correlation Length ◽  
Molecular Beam ◽  
Morphological Properties ◽  
X Ray ◽  
X Ray Scattering ◽  
Growth Interruption ◽  
Vertical Correlation ◽  
Ray Scattering

In this study, the effects of growth interruptions on the formation of the interfaces in GaAs∕AlAs multilayers are investigated. For that purpose, a series of different samples has been manufactured with molecular-beam epitaxy. The introduction of growth interruptions of 50 s after the deposition of the layer leads to a change in the morphological properties of the interfaces, in particular their correlation length. These modifications due to the growth interrupt are analyzed with diffuse X-ray scattering. As a result of the measurements, an extension of the lateral correlation length can be proved. By contrast, the vertical correlation of the interfaces is not affected.

Bi-Based Superconducting Multilayers Obtained by Molecular Beam Epitaxy

1999 ◽  
Vol 13 (09n10) ◽  
pp. 991-996
Author(s):  
M. Salvato ◽  
C. Attanasio ◽  
G. Carbone ◽  
T. Di Luccio ◽  
S. L. Prischepa ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Xrd Analysis ◽  
High Energy ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Model ◽  
Different Thickness

High temperature superconducting multilayers have been obtained depositing Bi2Sr2CuO6+δ(2201) and ACuO2 layers, where A is Ca or Sr, by Molecular Beam Epitaxy (MBE) on MgO and SrTiO3 substrates. The samples, formed by a sequence of 2201/ACuO2 bilayers, have different thickness of ACuO2 layers while the thickness of the 2201 layers is kept constant. The surface structure of each layer has been monitored by in situ Reflection High Energy Electron Diffraction (RHEED) analysis which has confirmed a 2D nucleation growth. X-ray diffraction (XRD) analysis has been used to confirm that the layered structure has been obtained. Moreover, one-dimensional X-ray kinematic diffraction model has been developed to interpret the experimental data and to estimate the period of the multilayers. Resistive measurements have shown that the electrical properties of the samples strongly depend on the thickness of the ACuO2 layers.

HCP-FCC Transition in Epitaxial Co-Cu Superlattices

1989 ◽  
Vol 151 ◽  
Author(s):  
F. J. Lamelas ◽  
C. H. Lee ◽  
Hui He ◽  
W. Vavra ◽  
Roy Clarke
Keyword(s):  
Molecular Beam Epitaxy ◽  
Magnetic Anisotropy ◽  
Detailed Analysis ◽  
Layer Thickness ◽  
Strong Correlation ◽  
Diffuse Scattering ◽  
Molecular Beam ◽  
Easy Axis ◽  
Structural Symmetry ◽  
X Ray

ABSTRACTA series of epitaxial Co-Cu superlattices has been grown on GaAs (110) substrates by molecular beam epitaxy. Detailed analysis of x-ray diffuse scattering scans along Co (101ℓ) reveals a crossover from from the bulk hcp phase of Co to metastable fcc stacking. Our measurements indicate a strong correlation between structural symmetry and the magnetic anisotropy in Co - noble metal superlattices. In particular, the perpendicular easy axis of magnetization onsets at Co layer thickness ♣ 19 Å in Cohcp-Au compared to only ˜11 Å in Cofcc-Cu.

Structural and Magnetic Properties of Epitaxial Co-Au Superlattices

1989 ◽  
Vol 151 ◽  
Author(s):  
C. H. Lee ◽  
Hui He ◽  
F. Lamelas ◽  
W. Vavra ◽  
C. Uher ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Molecular Beam ◽  
Easy Axis ◽  
Constant Thickness ◽  
Substrate Plane ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Axis Parallel ◽  
Structural And Magnetic Properties

ABSTRACTWe describe measurements on the structural and magnetic properties of Co–Au superlattices grown on Ge–buffered (110) GaAs by molecular beam epitaxy. Samples have been prepared with Co layer thicknesses ranging from 5–40Å and Au spacer layers of constant thickness, ∼ 16Å. X–ray scattering and high-resolution transmission electron microscopy show that the hcp Co layers grow epitaxially with the (0001) axis parallel to (111)Au and with the in–plane Co[1120] axis parallel to GaAs[001]. SQUID magnetometer measurements reveal a crossover in the magnetic anisotropy of the as–grown samples such that the easy axis is perpendicular to the substrate plane when the Co layer thickness is less than ∼19Å.

Real-Time X-Ray Scattering Study of Surface Dynamics on Au(111) During Ar+ Ion Irradiation

1998 ◽  
Vol 528 ◽  
Author(s):  
M.V. Ramana Murty ◽  
T. Curcic ◽  
A. Judy ◽  
B.H. Cooper ◽  
A.R. Woll ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Ion Irradiation ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Surface Dynamics ◽  
Surface Evolution ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

AbstractX-ray scattering is used to investigate the surface dynamics on Au(111) during Ar+ ion irradiation. During 500 eV Ar+ ion irradiation, we observe the three regimes of step retraction, quasi-layer-by-layer removal and three dimensional rough erosion, analagous to molecular beam epitaxy. The quasi-layer-by-layer sputtering regime has been studied to identify similarities and differences in surface evolution during ion irradiation and molecular beam epitaxy. X-ray measurements suggest that 500 eV Ar+ ion irradiation does not lead to stable adatom island formation. Also, in contrast to molecular beam epitaxy, adatom detachment and diffusion seems important in describing the surface kinetics during ion irradiation.

Recovery kinetics of the GaAs(001) surface in molecular beam epitaxy studied by in situ X-ray diffraction

2005 ◽  
Vol 357 (1-2) ◽  
pp. 165-169 ◽  
Author(s):  
Vladimir M. Kaganer ◽  
Wolfgang Braun ◽  
Bernd Jenichen ◽  
Klaus H. Ploog
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of
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