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.

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.

PERFORMANCE LIMITS OF SIMULATION MODELS FOR NOISE CHARACTERIZATION OF MM WAVE DEVICES

2007 ◽  
Vol 07 (03) ◽  
pp. L299-L312
Author(s):  
ALI ABOU-ELNOUR
Keyword(s):  
Boltzmann Transport Equation ◽  
Simulation Models ◽  
Two Dimensions ◽  
Boltzmann Transport ◽  
Performance Limits ◽  
Drift Diffusion ◽  
Model Equations ◽  
Accuracy Of Results ◽  
Noise Characterization

Based on Boltzmann transport equation, the drift-diffusion, hydrodynamic, and Monte-Carlo physical simulators are accurately developed. For each simulator, the model equations are self-consistently solved with Poisson equation, and with Schrödinger equation when quantization effects take place, in one and two-dimensions to characterize the operation and optimize the structure of mm-wave devices. The effects of the device dimensions, biasing conditions, and operating frequencies on the accuracy of results obtained from the simulators are thoroughly investigated. Based on physical understanding of the models, the simulation results are analyzed to fully determine the limits at which a certain device simulator can be accurately and efficiently used to characterize the noise behavior of mm-wave devices.

Thermal characterization of single-wall carbon nanotube bundles using the self-heating 3ω technique

2006 ◽  
Vol 100 (12) ◽  
pp. 124314 ◽  
Author(s):  
Jinbo Hou ◽  
Xinwei Wang ◽  
Pallavi Vellelacheruvu ◽  
Jiaqi Guo ◽  
Chang Liu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Thermal Characterization ◽  
The Self ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Nanotube Bundles ◽  
Self Heating ◽  
3Ω Technique

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

scholarly journals Thermoelectric characteristics of X$$_2$$YH$$_2$$ monolayers (X=Si, Ge; Y=P, As, Sb, Bi): a first-principles study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Ali Mohebpour ◽  
Shobair Mohammadi Mozvashi ◽  
Sahar Izadi Vishkayi ◽  
Meysam Bagheri Tagani
Keyword(s):  
Thermoelectric Materials ◽  
First Principles ◽  
Material Science ◽  
Figure Of Merit ◽  
Density Functional ◽  
Room Temperature ◽  
Boltzmann Transport Equation ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractEver since global warming emerged as a serious issue, the development of promising thermoelectric materials has been one of the main hot topics of material science. In this work, we provide an in-depth understanding of the thermoelectric properties of X$$_2$$ 2 YH$$_2$$ 2 monolayers (X=Si, Ge; Y=P, As, Sb, Bi) using the density functional theory combined with the Boltzmann transport equation. The results indicate that the monolayers have very low lattice thermal conductivities in the range of 0.09−0.27 Wm$$^{-1}$$ - 1 K$$^{-1}$$ - 1 at room temperature, which are correlated with the atomic masses of primitive cells. Ge$$_2$$ 2 PH$$_2$$ 2 and Si$$_2$$ 2 SbH$$_2$$ 2 possess the highest mobilities for hole (1894 cm$$^2$$ 2 V$$^{-1}$$ - 1 s$$^{-1}$$ - 1 ) and electron (1629 cm$$^2$$ 2 V$$^{-1}$$ - 1 s$$^{-1}$$ - 1 ), respectively. Si$$_2$$ 2 BiH$$_2$$ 2 shows the largest room-temperature figure of merit, $$ZT=2.85$$ Z T = 2.85 in the n-type doping ( $$\sim 3\times 10^{12}$$ ∼ 3 × 10 12  cm$$^{-2}$$ - 2 ), which is predicted to reach 3.49 at 800 K. Additionally, Si$$_2$$ 2 SbH$$_2$$ 2 and Si$$_2$$ 2 AsH$$_2$$ 2 are found to have considerable ZT values above 2 at room temperature. Our findings suggest that the mentioned monolayers are more efficient than the traditional thermoelectric materials such as Bi$$_2$$ 2 Te$$_3$$ 3 and stimulate experimental efforts for novel syntheses and applications.

Disparate strain response of the thermal transport properties of bilayer penta-graphene as compared to that of monolayer penta-graphene

2019 ◽  
Vol 21 (28) ◽  
pp. 15647-15655 ◽  
Author(s):  
Zhehao Sun ◽  
Kunpeng Yuan ◽  
Xiaoliang Zhang ◽  
Guangzhao Qin ◽  
Xiaojing Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Transport Equation ◽  
First Principles ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Boltzmann Transport Equation ◽  
Strain Response ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Strain Modulation

In this study, strain modulation of the lattice thermal conductivity of monolayer and bilayer penta-graphene (PG) at room temperature was investigated using first-principles calculations combined with the phonon Boltzmann transport equation.

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>

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.

The Effect of Spin Dependent Scattering from Impurities on Giant Magnetoresistance and Thermal Conductivity in Fe/Cr Multilayers

1991 ◽  
Vol 231 ◽  
Author(s):  
B.L. Johnson ◽  
R.E. Camley
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Low Temperature ◽  
Thermal Effects ◽  
Giant Magnetoresistance ◽  
Boltzmann Transport Equation ◽  
Equation Approach ◽  
Boltzmann Transport ◽  
Spin Dependent Scattering ◽  
Good Agreement

AbstractRecent experiments have tested the assumption that a spin-dependent asymmetry in scattering is responsible for the giant magnetoresistance (GMR) in Fe/Cr multilayers by introducing additional impurities (with different spin-dependent scattering asymmetries) at the interfaces. This paper presents a theoretical calculation based on a Boltzmann transport equation approach which is appropriate for these new experiments. We find that when impurities (Mn, V) are introduced which have a spin-dependent scattering asymmetry similar to that of Cr in Fe the GMR is not substantially changed. When impurities (Al, Ir) with a spin-dependent scattering asymmetry opposite to that of Cr in Fe are introduced there is a rapid degredation of the GMR. Our results are compared with experiment and good agreement is found provided that the magnitude of the scattering asymmetry in Al is reduced somewhat from low-temperature published values. It is argued that thermal effects could indeed provide such a reduction. We also point out that the thermal conductivity should undergo changes with magnetic field in these structures, since the thermal conductivity also depends upon electron mobility.

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