Thermal Characterization of Cu∕CoFe Multilayer for Giant Magnetoresistive Head Applications

2005 ◽  
Vol 128 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Y. Yang ◽  
R. M. White ◽  
M. Asheghi
Keyword(s):  
Electrical Resistance ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Thermal Characterization ◽  
Disk Drive ◽  
Multilayer Structures ◽  
Large Decrease ◽  
Resistance Thermometry

Giant magnetoresistance (GMR) head technology is one of the latest advancements in the hard disk drive (HDD) storage industry. The GMR head multilayer structure consists of alternating layers of extremely thin metallic ferromagnetic and nonmagnetic films. A large decrease in the electrical resistivity from antiparallel to parallel alignment of the film magnetizations is observed, known as the GMR effect. The present work characterizes the in-plane electrical and thermal conductivities of Cu∕CoFe GMR multilayer structures in the temperature range of 50K to 340K using Joule-heating and electrical resistance thermometry on suspended bridges. The thermal conductivity of the GMR layer monotonically increases from 25Wm−1K−1 (at 55K) to nearly 50Wm−1K−1 (at room temperature). We also report a GMR ratio of 17% and a large magnetothermal resistance effect (GMTR) of 25% in the Cu∕CoFe multilayer structure.

Thermal Characterization of Cu/CoFe Multilayer for Giant Magnetoresistive (GMR) Head Applications

2004 ◽  
Author(s):  
Y. Yang ◽  
M. Asheghi
Keyword(s):  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Boltzmann Transport Equation ◽  
Thermal Characterization ◽  
Disk Drive ◽  
Boltzmann Transport ◽  
Self Heating ◽  
Superlattice Structure ◽  
Metallic Ferromagnet

Giant Magnetoresistance (GMR) head technology is one of the latest advancement in hard disk drive (HDD) storage industry. The GMR head superlattice structure consists of alternating layers of extremely thin metallic ferromagnet and paramagnet films. A large decrease in the resistivity from antiparallel to parallel alignment of the film magnetizations can be observed, known as giant magnetoresistance (GMR) effect. The present work characterizes the in-plane electrical and thermal conductivities of Cu/CoFe GMR multilayer structure in the temperature range of 50 K to 340 K using Joule-heating and electrical resistance thermometry in suspended bridges. The thermal conductivity of the GMR layer monotonously increased from 25 Wm−1K−1 (at 55 K) to nearly 50 Wm−1K−1 (at room temperature). We also report the GMR ratio of 17% and a large negative magnetothermal resistance effect (GMTR) of 33% in Cu/CoFe superlattice structure. The Boltzmann transport equation (BTE) is used to estimate the GMR ratio, and to investigate the effect of repeats, as well as the spin-dependent interface and boundary scatting on the transport properties of the GMR structure. Aside from the interesting underlying physics, these data can be used in the predictions of the Electrostatic Discharge (ESD) failure and self-heating in GMR heads.

Field-Dependent Electrical and Thermal Characterization of Cu/CoFe Multilayer for Giant Magnetoresistive (GMR) Head Applications

2005 ◽  
Author(s):  
Y. Yang ◽  
J.-G. Zhu ◽  
R. M. White ◽  
M. Asheghi
Keyword(s):  
Thermal Transport ◽  
Giant Magnetoresistance ◽  
Thermal Characterization ◽  
Disk Drive ◽  
Multilayer Structures ◽  
Thermal Transport Property ◽  
Superlattice Structure ◽  
Metallic Ferromagnet ◽  
Interfacial Scattering

Giant Magnetoresistance (GMR) head technology is one of the latest advancement in hard disk drive (HDD) storage industry. The GMR head superlattice structure consists of alternating layers of extremely thin metallic ferromagnet and paramagnet films. A large decrease in the resistivity from antiparallel to parallel alignment of the film magnetizations can be observed, known as giant magnetoresistance (GMR) effect (Baibich et al., 1988; Binasch et al., 1989). The GMR effect is generally due to the spin dependent electron bulk and interfacial scattering in the GMR multilayer structures (Zhang et al., 1992). However, in order to understand the nature of the spin-dependent electron scattering mechanism responsible for the GMR effect, both electrical and thermal transport properties of such multilayer structures must be measured and understood. It is suggested that the thermal transport property measurements in GMR can be used to judge whether the scattering processes responsible for the GMR have elastic and/or inelastic components (Shi et al., 1996). Moreover, the GMR effect is anticipated to have a thermal counterpart, known as giant magnetothermal resistance (GMTR) effect in which the thermal conductivity shows a ‘giant’ change under magnetic field.

scholarly journals Thermal characterization of novel aliphatic polyesters with ether and thioether linkages

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Soccio ◽  
N. Lotti ◽  
L. Finelli ◽  
A. Munari
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Chemical Structure ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Aliphatic Polyesters ◽  
Good Thermal Stability

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s were synthesized for comparison and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of the presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tgvalue, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions

Thermal Conductivity Measurements of Thin Aluminum Layers Using Steady State Joule Heating and Electrical Resistance Thermometry in Suspended Bridges

2003 ◽  
Author(s):  
J. Reifenberg ◽  
R. England Voss ◽  
P. Rao ◽  
W. Schmitt ◽  
Y. Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Joule Heating ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Aluminum Film ◽  
Thin Metallic Film ◽  
Thin Aluminum ◽  
Film Layer ◽  
Resistance Thermometry

Thin metallic film layers are extensively used as the constituents of the micro-devices. The reliability of these devices, therefore, strongly depends on the thermal behavior of such film layers. Aluminum thin film layers are of particular interest in this respect. The lateral thermal conductivity of the aluminum film layers is measured, using the steady state electrical Joule heating and electrical resistance thermometry technique. Aluminum suspended microbridges of identical thicknesses (500 nm) and variable widths (16 to 18 μm) and/or lengths (200 to 500 μm) are fabricated, using conventional microfabrication processes. The lateral thermal conductivity of the 500 nm thick Aluminum film layer was found to be k = 174 ± 13 Wm−1 K−1, at room temperature (300 K).

Designing Stability into Thermally Reactive Plumbylenes

2018 ◽  
Author(s):  
Goran Bacic ◽  
David Zanders ◽  
Anjana Devi ◽  
Sean Barry
Keyword(s):  
Structural Analysis ◽  
Vapour Pressure ◽  
Room Temperature ◽  
Vapour Deposition ◽  
Thermal Characterization ◽  
Oxidative Cleavage ◽  
High Yield ◽  
Thermal Window ◽  
The Stability

We complete the picture of thermally stable and volatile <i>N-</i>heterocyclic metallylenes with the synthesis, structural analysis, and thermal characterization of <i>rac</i>-<i>N</i><sup>2</sup>,<i>N</i><sup>3</sup>-di-<i>tert</i>-butylbutane-2,3-diamido lead(II) (<b>1Pb</b>). Transamination of bis[bis(trimethylsilyl)amido] lead(II) with the free diamino ligand yields <b>1Pb</b> in high yield, whereas salt-metathesis leads to oxidative cleavage of the butane backbone and production of acetaldehyde-<i>tert-</i>butylimine. <b>1Pb</b> itself undergoes [2+2+1] cycloreversion at 150 °C to the same imine, but with a vapour pressure of 1 Torr at 94 °C a wide thermal window is available for use as a vapour deposition precursor.<div><br></div><div>We contrast this with the the extreme instability of its sisters <i>N</i><sup>2</sup>,<i>N</i><sup>3</sup>-di-<i>tert</i>-butylethane-2,3-diamido lead(II) (<b>2Pb</b>) and <i>N</i><sup>2</sup>,<i>N</i><sup>3</sup>-di-<i>tert</i>-butylethylene-2,3-diamido lead(II) (<b>3Pb</b>), which both reductively eliminate Pb(0) at or below room temperature. This is also in start contrast to the stability of the lighter Si, Ge and Sn congeners.</div>

Thermal Characterization of Electrical Resistance of 3D printed sensors

2021 ◽  
Author(s):  
Mattia Alessandro Ragolia ◽  
Attilio di Nisio ◽  
Anna Maria Lanzolla ◽  
Gianluca Percoco ◽  
Marco Scarpetta ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Thermal Characterization ◽  
Printed Sensors ◽  
3D Printed

Thermal Characterization of the 144 nm GMR Layer Using Microfabricated Suspended Structures

2003 ◽  
Author(s):  
Shu Zhang ◽  
Yizhang Yang ◽  
Sadegh M. Sadeghipour ◽  
Mehdi Asheghi
Keyword(s):  
Temperature Rise ◽  
Electrostatic Discharge ◽  
Thermal Characterization ◽  
Normal Operation ◽  
Maximum Temperature ◽  
Multilayer Structures ◽  
Accurate Knowledge ◽  
Gmr Sensor ◽  
Present Effort

The performance and reliability of GMR heads are influenced by the level of temperature rise, which may occur in the device during the normal operation or during an electrostatic discharge (ESD) event. However, the reliable electro-thermal modeling of the GMR sensor to predict the temperature rise, demands an accurate knowledge of the thermal properties of its constituent materials such as Al2O3 passivation and GMR layers. The lateral thermal conductivity of the GMR layer, which has not been measured previously, can largely influence the maximum temperature rise in the GMR sensor. The present effort will be directed at thermal characterization of the CoFe/Cu multilayer structures made of extremely thin periodic layers, using steady-state and frequency domain heating and thermometry in suspended bridges. The measurements are performed on several suspended structures with the lengths and widths in the range of 250 to 500 μm and 16 to 20 μm, respectively.

Analysis of the Ash from One Shanghai Plant Using XRD (X-Ray Diffraction)

2013 ◽  
Vol 664 ◽  
pp. 232-235
Author(s):  
Guo Xian Ma ◽  
Hai Ying Zhang
Keyword(s):  
Fly Ash ◽  
Pollution Control ◽  
Room Temperature ◽  
Thermal Characterization ◽  
Xrd Analysis ◽  
Air Pollution Control ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicates

This study aims to develop a methodology for thermal characterization of APC (air pollution control)fly ash using XRD (X-ray diffraction). It performed XRD analysis as a function of temperature between room temperature and 1200 °C. It is found that major mineralogical components of fly ash involve SiO2, CaCl2, Ca3Si2O7, Ca2SiO4–0.35H2O, Ca9Si6O21–H2O, K2Al2Si2O8–3.8H2O and AlCl3–4Al(OH)3–4H2O. Glass phases account for around 57%, which is conducive to reduction of energy in recycling of the ash. Salts decompose firstly with increase of temperature and then oxides derived from the decomposition process react with SiO2, forming silicates, calcium-silicates and aluminosilicates.

Thermal Conductivity of Porous Silicon Layers for MEMS

1999 ◽  
Author(s):  
Uma Srinivasan ◽  
Peter Breh ◽  
Mehdi Asheghi ◽  
Maxat Touzelbaev ◽  
Kenneth E. Goodson
Keyword(s):  
Thermal Conductivity ◽  
Porous Silicon ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Single Crystal Silicon ◽  
Silicon Layer ◽  
Boundary Scattering ◽  
Conductivity Data ◽  
Crystal Silicon ◽  
Resistance Thermometry

Abstract Porous silicon is a promising material for MEMS because of its unique electrical, thermal, optical, and absorptive properties. This work measures the thermal conductivity of a silicon layer with 40 percent porosity at temperatures between 20 and 300 K using Joule heating and electrical-resistance thermometry. The room-temperature thermal conductivity is 0.43 Wm−1K−1, which is almost three orders of magnitude less than the value for single-crystal silicon. The data are interpreted using a new model based on electron microscopy, which shows a sponge-like morphology with embedded crystalline regions. The model separately treats the contributions of the sponge-like material, in which the solid regions are assumed to be amorphous silicon, and the larger crystallites, in which the conductivity is reduced by boundary scattering. The present work is particularly useful for MEMS based on silicon with porosity below 50 percent, for which no thermal conductivity data were previously available.

scholarly journals Electrical and Thermal Characterization of Electrospun PVP Nanocomposite Fibers

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Waseem S. Khan ◽  
Ramazan Asmatulu ◽  
Mohamed M. Eltabey
Keyword(s):  
Electrical Resistance ◽  
Multiwall Carbon Nanotubes ◽  
Thermal Characterization ◽  
Industrial Applications ◽  
Electrospinning Process ◽  
Electrically Conductive ◽  
Electrical Conductivities ◽  
Process System ◽  
Nanocomposite Fibers

Polyvinylpyrrolidone (PVP) solutions incorporated with multiwall carbon nanotubes (MWCNTs) were electrospun at various weight percentages, and then the electrical resistance and some thermal properties of these nanocomposite fibers were determined using a high-accuracy electrical resistance measurement device. During the electrospinning process, system and process parameters, such as concentrations, applied voltage, tip-to-collector distance, and pump speeds, were optimized to receive the consistent nanocomposite fibers. When polymers are used in many industrial applications, they require high electrical and thermal conductivities. Most polymers exhibit low electrical conductivity values; however, in the presence of conductive inclusions, the electrical resistance of the MWCNT fibers was reduced from 50 MΩ to below 5 MΩ, which may be attributed to the higher electrical conductivities of these nanoscale inclusions and fewer voids under the applied loads. This study may open up new possibilities in the field for developing electrically conductive novel nanomaterials and devices for various scientific and technological applications.

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