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A micromagnetic simulation-based comparative study between perpendicular magnetic recording (PMR) and heat-assisted magnetic recording (HAMR) has been performed. Signal-to-noise ratio (SNR) is adopted as the metric of comparison, and various system parameters are considered, including fly-height (FH), write-track distance, and rotary motion of the head-stack-assembly (skew). It is found that even a HAMR system with a wide 60 nm full-width at half-maximum thermal profile demonstrates better SNR performance when compared to an optimized PMR system at a magnetic FH of 8 nm. The impact of skew on a single reader system is found to be minor for both PMR and HAMR, but the impact on a dual reader 2-D recording system differs substantially. In particular, the resolution for small bit detection depends greatly on reader shield orientation to the HAMR-written curved transition beneath the read free layer.

Voltage-controlled switching of CoFeB/MgO magnetic tunnel junctions has been analyzed using micromagnetic simulation that includes thermal fluctuations and surface roughness. It is shown that the large samples typically studied experimentally switch by domain wall motion, nucleated at points where the CoFeB is slightly thicker. This is a consequence of small thickness variations producing large percentage changes in the anisotropy owing to the near balance of interface anisotropy and shape anisotropy in these films. It is also found that these films are likely never saturated at the experimental fields employed owing to the importance of thermal fluctuations in the near 2-D geometry.

Magnetic tunnel junctions with perpendicular magnetic anisotropy are investigated using a conductive atomic force microscope. The $1.23\ensuremath{-}\mathrm{nm}$ ${\mathrm{Co}}_{40}{\mathrm{Fe}}_{40}{\mathrm{B}}_{20}$ recording layer coercivity exhibits a size dependence which suggests single-domain behavior for diameters $\ensuremath{\le}\phantom{\rule{0.16em}{0ex}}100$ nm. Focusing on devices with diameters smaller than 100 nm, we determine the effect of voltage and size on the effective device anisotropy ${K}_{\text{eff}}$ using two different techniques. ${K}_{\text{eff}}$ is extracted both from distributions of the switching fields of the recording and reference layers and from measurement of thermal fluctuations of the recording layer magnetization when a field close to the switching field is applied. The results from both sets of measurements reveal that ${K}_{\text{eff}}$ increases monotonically with decreasing junction diameter, consistent with the size dependence of the demagnetization energy density. We demonstrate that ${K}_{\text{eff}}$ can be controlled with a voltage down to the smallest size measured, 64 nm.

The performance and characteristics of Double Gate MOSFET with high dielectric constant (high-κ) gate stack have been analyzed and compared with those of conventional pure SiO2 gate MOSFET. Quantum Ballistic Transport Model has been used to demonstrate the performance of the device in terms of threshold voltage, drain current in both low and high drain voltage regions and subthreshold swing. The effect of temperature on the threshold voltage and subthreshold characteristics has also been observed. This work reveals that improved performance of this structure can be achieved by scaling the gate length and illustrates its superiority over SiO2 gate MOSFETs in achieving long-term ITRS goals.

A technique for micromagnetic simulation of the magnetoelectric (ME) effect in Cr2O3 based structures has been developed. It has been observed that the microscopic ME susceptibility differs significantly from the experimentally measured values. The deviation between the two susceptibilities becomes more prominent near the Curie temperature, affecting the operation of the device at room temperature. A fully electric field controlled ME switching element has been proposed for use at technologically interesting densities: it employs quantum mechanical exchange at the boundaries instead of the applied magnetic field needed in traditional switching schemes. After establishing temperature dependent physics-based parameters, switching performances have been studied for different temperatures, applied electric fields, and Cr2O3 cross-sections. It has been found that our proposed use of quantum mechanical exchange favors reduced electric field operation and enhanced scalability while retaining reliable thermal stability.A technique for micromagnetic simulation of the magnetoelectric (ME) effect in Cr2O3 based structures has been developed. It has been observed that the microscopic ME susceptibility differs significantly from the experimentally measured values. The deviation between the two susceptibilities becomes more prominent near the Curie temperature, affecting the operation of the device at room temperature. A fully electric field controlled ME switching element has been proposed for use at technologically interesting densities: it employs quantum mechanical exchange at the boundaries instead of the applied magnetic field needed in traditional switching schemes. After establishing temperature dependent physics-based parameters, switching performances have been studied for different temperatures, applied electric fields, and Cr2O3 cross-sections. It has been found that our proposed use of quantum mechanical exchange favors reduced electric field operation and enhanced scalability while retaining reliable thermal sta...

Spin torque MRAM offers the possibility of ultrahigh density nonvolatile data storage. However, current devices require excessive current densities to switch the magnetization: this greatly limits commercial implementation. Previous researchers [1]-[2] have experimentally demonstrated that the application of approximately 1V across an MgO thin film allows a neighboring ferromagnet to switch with much reduced applied field. It has been argued that this is caused by the voltage adjusting the Fermi level of the ferromagnet in such a way that the magnetic anisotropy is substantially reduced.

Exchange bias in a magnetoelectric Cr2O3/ferromagnet system at finite temperature, based on the formation of a domain wall in Cr2O3, has been investigated using Monte Carlo simulation. It has been shown that the calculation of the exchange bias based on domain wall formation yields a more realistic value than that calculated using interfacial exchange coupling between Cr2O3 and the adjacent ferromagnet. Possible shortcoming of the magnetoelectric effect in setting the switchable exchange bias in the low temperature regime has also been demonstrated based on an energy threshold requirement. Specifically, it has been found that the magnetoelectric effect becomes intrinsically less effective in switching the exchange bias at low temperature, thus making the applicability of the system limited to only a certain temperature range.

The threshold voltage and capacitance voltage characteristics of ultra-thin Silicon-on-Insulator MOSFET are greatly influenced by the thickness and doping concentration of the silicon film. In this work, the capacitance voltage characteristics and threshold voltage of the device have been analyzed with quantum mechanical effects using the Self-Consistent model. Reduction of channel thickness and adding doping impurities cause an increase in the threshold voltage. Moreover, the temperature effects cause a significant amount of threshold voltage shift. The temperature dependence of threshold voltage has also been observed with Self- Consistent approach which are well supported from experimental performance of practical devices., {"references":["S. Kim, T. Shim, and J. Park, \"Electrical behavior of ultra-thin body\nsilicon-on-insulator n-mosfets at a high operating temperaure,\" Journal\nof Ceramic Processing Reseach, vol. 10, no. 4, pp. 507 -511, 2009.","Y. Omura, A. Nakakubo, and H. Nakatsuji, \"Quantum mechanical\neffect in temperature dependence of threshold voltage of extremely\nthin soi mosfets,\" Solid-State Electronics, vol. 48, no. 9, pp. 1661 -\n1666, 2004, non Volatile Memories with discrete storage nodes. (Online).\nAvailable: http://www.sciencedirect.com/science/article/B6TY5-\n4CDHD5K-2/2/4ce9ebb7270ac96308d1ce7efda02d80","H.-K. Lim and J. Fossum, \"Threshold voltage of thin-film siliconon-\ninsulator (soi) mosfet-s,\" Electron Devices, IEEE Transactions on,\nvol. 30, no. 10, pp. 1244 - 1251, oct 1983.","T. Ernst, S. Cristoloveanu, G. Ghibaudo, T. Ouisse, S. Horiguchi, Y. Ono,\nY. Takahashi, and K. Murase, \"Ultimately thin double-gate soi mosfets,\"\nElectron Devices, IEEE Transactions on, vol. 50, no. 3, pp. 830 - 838,\nmarch 2003.","Y.-K. Choi, K. Asano, N. Lindert, V. Subramanian, T.-J. King, J. Bokor,\nand C. Hu, \"Ultra-thin body soi mosfet for deep-sub-tenth micron era,\" in\nElectron Devices Meeting, 1999. IEDM Technical Digest. 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Over the past decade, obesity has become a major health issue in the western world, and is very rapidly becoming a concern for eastern countries as well. In the most basic sense, obesity results from an imbalance between energy intake and energy expenditure. However, the complex disease that is obesity arises as a result of the insufficient energy consumption, resulting in adiposity, the increase of triglyceride storage in adipocytes, body weight gain, and an increased risk of obesity co-morbidities. As the prevalence of obesity is expected to increase over the next 20 years, the identification of novel anti-obesity targets has become paramount in the search for an efficacious and compliance-friendly obesity therapy. In an effort to identify and classify potential anti-obesity targets as experimental candidates for obesity therapy, WAT (white adipose tissue) from Hmga2-/-, Lepob.Lepob double knockout mice, Hmga2+/+ mice, Hmga2-/- mice, and Lepob/Lepob mice were run on microarray to determine gene expression profiles for each genotype. Exclusion criteria were added, and a list of 138 adipocyte-specific genes remained. The genes were then characterized through bioinformatics according to 6 parameters: 1) chromosomal location in mouse genome; 2) chromosomal location in human genome; 3) subcellular localization; 4) function; 5) knockout phenotype in mice; 6) obesity-related QTLs in human genome. After characterization, each gene was evaluated in greater detail and filtered to form a list of candidates for experimental analysis to evaluate anti-obesity effectiveness. The list of 138 genes was finally narrowed to 10 genes, 6 of which were present in the top 25 most highly expressed genes in adipocyte-rich WAT. Preliminary experimental analysis reveals diminished weight gain and overall decreased body weight in mice upon peptide inhibition for one gene from the filtered list. While we have only begun evaluating one gene, thus far, the results are encouraging in that the method used to develop and filter such a list of genes is proving to be validated. Further experimental research is required in order to fully validate each potential candidate; however such an approach, to determine solid candidates, appears promising.

Wave function penetration has significant impact on nanoscale devices having ultrathin gate oxide. Although wave function penetration effects on ballistic drain current and capacitance-voltage characteristics in nanoscale devices have been reported in literature, to the best of the authors’ knowledge, effects of temperature on drain current incorporating with and without wave function penetration are yet to be studied. In this work, the impacts of temperature, gate dielectric and film thickness in wave function penetration on ballistic drain current of nanoscale double-gate (DG) MOSFETs are presented. The effects are observed using two-dimensional self-consistent solution of Schrodinger and Poisson equations. It has been obtained that temperature effect on drain current is greatly dependent on silicon surface orientation. Drain current of DG MOSFETs fabricated on $$\langle110\rangle$$ surface is more sensitive to temperature compared to $$\langle001\rangle$$ surface. This has been obtained for both the cases with and without incorporating wave function penetration in silicon–gate oxide interface. Electrostatics behind this phenomenon has been explained from the transmission probability of electrons from source to drain which is largely influenced by temperature on $$\langle110\rangle$$ surface compared to $$\langle001\rangle.$$ Moreover, the transmission coefficient is significantly affected by wave function penetration in $$\langle110\rangle \hbox{ than }\langle001\rangle$$ surface. Both these demonstrate greater sensitivity of temperature and wave function penetration in $$\langle110\rangle$$ silicon surface orientation compared to $$\langle001\rangle.$$ Furthermore, gate dielectric with lower conduction band offset and device scaling with thin channel thickness tend to exhibit greater impact of wave function penetration.