scholarly journals Critical thickness investigation of magnetic properties in exchange-coupled bilayers

2011 ◽  
Vol 83 (22) ◽  
Author(s):  
R. L. Rodríguez-Suárez ◽  
L. H. Vilela-Leão ◽  
T. Bueno ◽  
A. B. Oliveira ◽  
J. R. L. de Almeida ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Critical Thickness ◽  
Coupled Bilayers

Formative time and structure of martensite from amorphous FeNi films

1978 ◽  
Vol 36 (1) ◽  
pp. 646-647
Author(s):  
O. Bostanjoglo ◽  
R. Liedtke
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Critical Thickness ◽  
Amorphous State ◽  
Bright Field Image ◽  
Amorphous Films ◽  
Bright Field ◽  
Formative Time ◽  
Carbon Foils ◽  
Fast Detector

Using a fast detector the applicability of CTEM was extended to follow phase transformations in the nanoseconds range. Iron-rich FeNi films vapour-quenched at 4 K grow in an amorphous state with peculiar crystallographic and magnetic properties (1). On exceeding a critical thickness or on heating amorphous films with inferior thickness up to a critical temperature, the films martensiticly crystallized. This diffusionless transformation occurred in such films where the amorphous phase was stabilized by stress and not by reacting gases.The present paper reports investigations on both the structure of martensite and on the propagation of martensitic crystallization of amorphous 70 at % FeNi films. They were grown at 4 K on carbon foils in the EM as previously described (1). The propagation of the phase transformation was investigated by following the change of the bright-field image intensity with fast scintillator, photomultiplier and oscilloscope. Crystallization processes occurring in areas of 1.5 μm ∅ and within 10 ns were resolved in first experiments (fig. 3).

Variations in Magnetic Properties of SmCo5/Fe Exchange-Coupled Bilayers with Increasing Fe Thickness

2011 ◽  
Vol 37 (1) ◽  
pp. 251-254 ◽  
Author(s):  
Furrukh Shahzad ◽  
Saadat Anwar Siddiqi ◽  
Xu Jing ◽  
Bai Hong-Liang
Keyword(s):  
Magnetic Properties ◽  
Coupled Bilayers

Nanoclusters—critical thickness—magnetic properties relationship in Nd90−Fe Al10 amorphous ribbons

2004 ◽  
Vol 272-276 ◽  
pp. E1137-E1139 ◽  
Author(s):  
Nicoleta Lupu ◽  
Horia Chiriac ◽  
Akira Takeuchi ◽  
Akihisa Inoue
Keyword(s):  
Magnetic Properties ◽  
Critical Thickness ◽  
Amorphous Ribbons

Magnetic properties and anisotropic magnetoresistance of antiperovskite nitride Mn3GaN/Co3FeN exchange-coupled bilayers

2015 ◽  
Vol 117 (17) ◽  
pp. 17D725 ◽  
Author(s):  
H. Sakakibara ◽  
H. Ando ◽  
Y. Kuroki ◽  
S. Kawai ◽  
K. Ueda ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Anisotropic Magnetoresistance ◽  
Coupled Bilayers

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

Microstructure in soft magnetic E3 (S1, Al) (Sendust) alloys

1988 ◽  
Vol 46 ◽  
pp. 770-771
Author(s):  
June D. Kim
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Ternary Phase Diagram ◽  
Vertical Tube ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Soft Magnetic ◽  
Quenching Temperature ◽  
Thin Foils ◽  
Vertical Tube Furnace

Iron-base alloys containing 8-11 wt.% Si, 4-8 wt.% Al, known as “Sendust” alloys, show excellent soft magnetic properties. These magnetic properties are strongly dependent on heat treatment conditions, especially on the quenching temperature following annealing. But little has been known about the microstructure and the Fe-Si-Al ternary phase diagram has not been established. In the present investigation, transmission electron microscopy (TEM) has been used to study the microstructure in a Sendust alloy as a function of temperature.An Fe-9.34 wt.% Si-5.34 wt.% Al (approximately Fe3Si0.6Al0.4) alloy was prepared by vacuum induction melting, and homogenized at 1,200°C for 5 hrs. Specimens were heat-treated in a vertical tube furnace in air, and the temperature was controlled to an accuracy of ±2°C. Thin foils for TEM observation were prepared by jet polishing using a mixture of perchloric acid 15% and acetic acid 85% at 10V and ∼13°C. Electron microscopy was performed using a Philips EM 301 microscope.

Various technic for the measurement of step thickness on crystal surfaces

1978 ◽  
Vol 36 (1) ◽  
pp. 438-439
Author(s):  
C. Boulesteix ◽  
C. Colliex ◽  
C. Mory ◽  
B. Pardo ◽  
D. Renard
Keyword(s):  
Critical Thickness ◽  
Symmetric Case ◽  
Transmitted Intensity ◽  
Crystal Surfaces ◽  
Bright Field ◽  
Excited Wave ◽  
Highly Sensitive ◽  
Contrast Mechanisms ◽  
Step Thickness ◽  
Thickness Variations

Contrast mechanisms, which are responsible of the various types of image formation, are generally thickness dependant. In the following, two imaging modes in the 100 kV CTEM are described : they are highly sensitive to thickness variations and can be used for quantitative estimations of step heights.Detailed calculations (1) of the bright-field intensity have been carried out in the 3 (or 2N+l)-beam symmetric case. They show that in given conditions, the two important symmetric Bloch waves interfere most strongly at a critical thickness for which they have equal emergent amplitudes (the more excited wave at the entrance surface is also the more absorbed). The transmitted intensity I for a Nd2O3 specimen has been calculated as a function of thickness t. The capacity of the method to detect a step and measure its height can be more clearly deduced from a plot of dl/Idt as shown in fig. 1.

Structural properties of GaAs/InGaAs/GaAs (001) and InGaAs/GaAs (001) heterostructures and correlation with electronic properties

1990 ◽  
Vol 48 (4) ◽  
pp. 602-603
Author(s):  
J.M. Bonar ◽  
R. Hull ◽  
R. Malik ◽  
R. Ryan ◽  
J.F. Walker
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Gaas Substrate ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Band Offset ◽  
Misfit Dislocations ◽  
Gaas Substrates ◽  
Gaas Structure ◽  
Low X

In this study we have examined a series of strained heteropeitaxial GaAs/InGaAs/GaAs and InGaAs/GaAs structures, both on (001) GaAs substrates. These heterostructures are potentially very interesting from a device standpoint because of improved band gap properties (InAs has a much smaller band gap than GaAs so there is a large band offset at the InGaAs/GaAs interface), and because of the much higher mobility of InAs. However, there is a 7.2% lattice mismatch between InAs and GaAs, so an InxGa1-xAs layer in a GaAs structure with even relatively low x will have a large amount of strain, and misfit dislocations are expected to form above some critical thickness. We attempt here to correlate the effect of misfit dislocations on the electronic properties of this material.The samples we examined consisted of 200Å InxGa1-xAs layered in a hetero-junction bipolar transistor (HBT) structure (InxGa1-xAs on top of a (001) GaAs buffer, followed by more GaAs, then a layer of AlGaAs and a GaAs cap), and a series consisting of a 200Å layer of InxGa1-xAs on a (001) GaAs substrate.

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