Different Temperature Dependencies of Magnetic Interface and Volume Anisotropies in Gd / W(110)

1995 ◽  
Vol 384 ◽  
Author(s):  
M. Farle ◽  
B. Schulz ◽  
A. Aspelmeier ◽  
G. Andre ◽  
K. Baberschke
Keyword(s):  
Film Thickness ◽  
Magnetic Anisotropy ◽  
Temperature Dependence ◽  
Ferromagnetic Resonance ◽  
Magnetocrystalline Anisotropy ◽  
The Other ◽  
Spin Interaction ◽  
Reduced Temperature ◽  
Thickness Independent

ABSTRACTThe magnetic anisotropy of epitaxial Gd(0001) films on W(110) is determined as a function of temperature (150 to 350 K) and film thickness (9 to 30 monolayers) by in situ ferromagnetic resonance. It is found that the usual analysis in terms of a thickness independent part KV and a thickness dependent contribution 2KS/d must be performed at the same reduced temperature t = T/Tc(d). Kv shows qualitatively the same temperature dependence as the magnetocrystalline anisotropy of bulk Gd. It changes in sign near 0.7 Tc and does not vanish at Tc. KS on the other hand decreases linearly from 1.2 meV/atom at 0.6.Tc to zero at Tc. It appears that the intrinsic origin for Kv and KS is fundamentally different. The vanishing of KS at Tc indicates that two-ion anisotropy (spin-spin interaction) is dominating the interface anisotropy. The non- zero KV(T≥Tc) is likely due to a single ion magnetic anisotropy which is known for bulk Gd.

Misfit Strain Relief Beyond the Critical Thickness Using Curvature Measurements and in Situ Characterization of the Magneto-Optic Kerr Effect

1994 ◽  
Vol 356 ◽  
Author(s):  
H. E. Inglefield ◽  
G. Bochi ◽  
C. A. Ballentine ◽  
R. C. O’Handley ◽  
C. V. Thompson
Keyword(s):  
Film Thickness ◽  
Magnetic Anisotropy ◽  
Kerr Effect ◽  
Critical Thickness ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Wafer Curvature ◽  
Curvature Measurements ◽  
Magneto Optic

AbstractEpitaxial misfit has been characterized in Ni/Cu/Si (100) as a function of Ni film thickness using wafer curvature measurements. This strain can be related to measurements of magnetic anisotropy made in the deposition system using the magneto-optic Kerr effect. Films were deposited using molecular beam epitaxy (MBE) with varying Ni epilayer thickness between 10 and 1000Å. The change in wafer curvature due to misfit strain was measured using optical interferometry and the strain was calculated using Stoney’s equation. Transmission electron microscopy was used to characterize misfit dislocations at the Ni/Cu interface. It has been determined that misfit strain can have a very strong effect on magnetic anisotropy, particularly in the regime between the critical thickness and complete misfit accommodation, where strain has been found to decrease significantly as a function of film thickness. A critical strain has been determined at which a transition in the direction of magnetization easy axis from perpendicular to the film to in the film plane occurs. This discovery allows the use of Kerr effect measurements to characterize misfit strain in situ.

scholarly journals Patterns of sarcomere activation, temperature dependence, and effect of ryanodine in chemically skinned cardiac fibers.

1986 ◽  
Vol 87 (6) ◽  
pp. 885-905 ◽  
Author(s):  
A Lundblad ◽  
H Gonzalez-Serratos ◽  
G Inesi ◽  
J Swanson ◽  
P Paolini
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Temperature Dependence ◽  
Calcium Release ◽  
Contractile Activity ◽  
The Other ◽  
Calcium Blockers ◽  
Calcium Accumulation ◽  
Contractile Activation

Functionally skinned and electrochemically shunted myocytes were prepared by perfusing rat hearts with collagenase in order to obtain a technically improved measurement of sarcomere dynamics and to evaluate the role of sarcoplasmic reticulum in situ with respect to contractile activation. In the presence of micromolar calcium, the myocytes exhibited phasic and propagated contraction waves beginning at one end and proceeding along the myocyte. Beating rates, the propagation velocity of the activation wave, and single sarcomere shortening and relaxation velocities were obtained by manual or automated analysis of 16-mm film recorded at 170 frames/s from a camera attached to a microscope that was equipped with a temperature-controlled stage. In parallel experiments, calcium accumulation by the sarcoplasmic reticulum of the myocytes in situ was measured by direct isotopic tracer methods. The frequency (10-38 min-1) of spontaneous contractions, the velocity (1.9-7.4 microns . s-1) of sarcomere shortening, and the velocity (1.7-6.8 microns . s-1) of sarcomere relaxation displayed identical temperature dependences (Q10 = 2.2), which are similar to that of the calcium pump of sarcoplasmic reticulum and are consistent with a rate limit imposed by enzyme-catalyzed mechanisms on all these parameters. On the other hand, the velocity (77-159 microns . s-1) of sequential sarcomere activation displayed a lower temperature dependence (Q10 = 1.5), which is consistent with a diffusion-limited and self-propagating release of calcium from one sarcomere to the other. The phasic contractile activity of the dissociated myocytes was inhibited by 10(-8)-10(6) M ryanodine (and not by myolemmal calcium blockers) under conditions in which calcium accumulation by sarcoplasmic reticulum in situ was demonstrated to proceed optimally. The effect of ryanodine is attributed to an interaction of this drug with sarcotubular structures, producing inhibition of calcium release from the sarcoplasmic reticulum. The consequent lack of sarcomere activation underlines the role of sarcoplasmic reticulum uptake and release in the phasic contractile activation of the electrochemically shunted myocytes.

Curvature Measurements of Tri-Material Structures Under Thermal Excursion

1991 ◽  
Vol 226 ◽  
Author(s):  
Guo-Quan Lu ◽  
Boris Mogilevsky ◽  
Tapan K. Gupta
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Temperature Dependence ◽  
The Other ◽  
Thermal Expansion Mismatch ◽  
Ceramic Substrates ◽  
Die Attach ◽  
Curvature Measurements ◽  
Thermal Excursion

AbstractThe bending curvatures of tri-material plates have been measured using in situ laser reflection technique at temperatures ranging from 20°C to 160°C. The tri-material structures are formed by attaching silicon wafers to ceramic substrates with die-attach adhesives from solder-like (elastic modulus ≈ 24 GPa) to gel-like (elastic modulus ≈ 0.003 GPa) characteristics. The temperature dependence of curvature as a result of the thermal expansion mismatch is measured. The structure bonded by the gel-like adhesive has substantially lower, about a factor of ten less, bending than the structures attached by the other two types of adhesives. We found good agreements between the measurements and the theoretical derivations by Suhir[1] for the bending curvature of finite tri-material assembly.

Planarization Ability of Chemical Mechanical Planarization (Cmp) Processes

1994 ◽  
Vol 337 ◽  
Author(s):  
Matt Stell ◽  
Rahul Jairath ◽  
Mukesh Desai ◽  
Robert Tolles
Keyword(s):  
Film Thickness ◽  
Chemical Mechanical Planarization ◽  
Silica Particles ◽  
The Other ◽  
Ph Values ◽  
Enhanced Solubility ◽  
Experimental Approaches ◽  
Thickness Measurements

ABSTRACTMethods for determining planarization ability of CMP were explored. Options included film thickness measurements of the dielectric over metal and field, TIR measurements using profilometry, and a combination of the two. The attempt to observe the in situ change in the topography was addressed in two distinct experimental approaches. The first approach involved processing wafers for predetermined intervals. The other approach processed different wafers for different amounts of time. The effects of down force and platen rpm on planarization ability were studied using the first approach. Results indicate that planarization is more efficient at higher down forces and higher platen rpm. Slurry property effects were examined using the second method. The planarization ability appears to suffer at elevated pH values. This is attributed to both the enhanced solubility of the silica particles and the dielectric itself.

Fe2+ Contents and Magnetocrystalline Anisotropy in Iron Defect LiZnTiMn Ferrites

2002 ◽  
Vol 17 (7) ◽  
pp. 1702-1705 ◽  
Author(s):  
A. Iglesias ◽  
J. Balmaseda ◽  
A. González Arias
Keyword(s):  
Ferromagnetic Resonance ◽  
High Spin ◽  
Magnetocrystalline Anisotropy ◽  
The Other ◽  
Compensation Point ◽  
Octahedral Sites ◽  
Resonance Linewidth ◽  
Other Hand ◽  
Landé Factor ◽  
Ferromagnetic Resonance Linewidth

An investigation of the effects of the iron defect k in LiZnTiMn ferrites using Mössbauer spectroscopy and ferromagnetic resonance techniques was carried out in single-phased samples. Results show that the isomer shifts have values corresponding to a compound with either low-spin Fe(II), low-spin Fe(III), or high-spin Fe(III). On the other hand, the Lande factor and the ferromagnetic resonance linewidth disclosed that g is always very close to 2, being equal to 2.02 when k = 0.06. A minimum in ΔH was detected for this value of k. From these results, the possible presence of Fe2+ in the samples could be excluded, and it was concluded that the changes in ΔH are due to the variation of the Fe(III) contents in the tetrahedral and octahedral sites. The existence of the minimum in ΔH is due to a compensation point in the magnetocrystalline anisotropy.

scholarly journals Electronic-Excitation-Induced Processing in GaSb Compound Nanoparticles

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
H. Yasuda ◽  
H. Mori
Keyword(s):  
Temperature Dependence ◽  
Point Defects ◽  
Structural Changes ◽  
Electronic Excitation ◽  
The Other ◽  
Two Phase ◽  
Electron Dose ◽  
Total Electron ◽  
Transmission Electron

Temperature dependence of electronic-excitation-induced structural changes in nanoparticles has been studied by in situ transmission electron microscopy. When GaSb nanoparticles kept at 340 K were excited by 25 keV electrons, the compound transforms to the porous compound or the two-phase structure consisting of an antimony core and a gallium shell with increasing the total electron dose. On the other hand, in GaSb nanoparticles kept at 293 K the structure remains the original compound phase. It is suggested that such temperature dependence of the structural changes may arise from synergetic behaviors of point defects introduced athermally by the excitation and thermal mobility.

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