Ultrafast and low-energy switching in voltage-controlled elliptical pMTJ

Switching magnetization in a perpendicular magnetic tunnel junction (pMTJ) via voltage controlled magnetic anisotropy (VCMA) has shown the potential to markedly reduce the switching energy. However, the requirement of an external magnetic field poses a critical bottleneck for its practical applications. In this work, we propose an elliptical-shaped pMTJ to eliminate the requirement of providing an external field by an additional circuit. We demonstrate that a 10 nm thick in-plane magnetized bias layer (BL) separated by a metallic spacer of 3 nm from the free layer (FL) can be engineered within the MTJ stack to provide the 50 mT bias magnetic field for switching. By conducting macrospin simulation, we find that a fast switching in 0.38 ns with energy consumption as low as 0.3 fJ at a voltage of 1.6 V can be achieved. Furthermore, we study the phase diagram of switching probability, showing that a pulse duration margin of 0.15 ns is obtained and a low-voltage operation (~ 1 V) is favored. Finally, the MTJ scalability is considered, and it is found that scaling-down may not be appealing in terms of both the energy consumption and the switching time for the precession based VCMA switching.Comment: There are 28 pages and 5 figure

Electric-field-induced Three-terminal pMTJ Switching in the absence of an External Magnetic Field

Since it is undesirable to require an external magnetic field for on-chip memory applications, we investigate the use of a Rashba effective field alternatively for assisting the electric-field-induced switching operation of a three terminal perpendicular magnetic tunnel junction (pMTJ). By conducting macro-spin simulation, we show that a pMTJ with thermal stability of 61 can be switched in 0.5 ns consuming a switching energy of 6 fJ, and the voltage operation margin can be improved to 0.8 ns. Furthermore, the results also demonstrate that a heavy metal system that can provide large field-like torque rather than damping-like torque is favored for the switching.Comment: there are 10 pages and 5 figures in this fil

Examining reasons for irresponsible driving and improving the effectiveness of road safety interventions through social marketing.

This dissertation aims to examine the factors influencing the young driver to commit the distracted driving behavior especially from the individual perspectives. After reviewing the literature, the main factors can be divided into three types which are the threatening advertisement, individual factors and the social influence. This study has applied qualitative research method to collect the data and the data was generated from in-depth interviews conducted with 12 UK residents who possess the current driver licenses. The previous studies have largely focused on examining the effectiveness of the threatening advertisement in order to prevent this kind of irresponsible driving behavior, while the effects of using fear appeals are contentious. However, according to the implication of the previous researches, the personality and the ability of self-regulation could be the important indicators in preventing the distracted driving behavior but both of them are not well examined. Therefore, this research is trying to fill the research gap with purposes to specifically investigate the influence of personality and self-regulation in the distracted driving. The main findings identified by this study are supported by the previous research. The driving behavior of the young people is affected by the application of fear appeals in advertisements, individual perspectives (level of the awareness, the ability of self-regulation), social norms (parents and peer passengers). In addition, it is worthy to mention that the personality is not a key component in affecting the driving behavior in terms of the individual perspectives. However, the level of awareness and the ability of self-regulation are important determinants affecting their choice while driving. The findings have opened new directions for future study which is to improve young drivers’ awareness by establishing correct perceptions of driving and the distracted driving instead of strongly stressing to use fear appeals. Finally, managerial implications and limitations are discussed

Reduced contrast sensitivity function is correlated with changes to cone photoreceptors in simple high myopia

PurposeTo investigate the contrast sensitivity function (CSF) changes in simple high myopia (SHM) and evaluate the correlations between these changes with the early changes in the retinal microstructure.MethodsThis prospective study comprised 81 subjects, 20 with emmetropia (EM), 26 with low myopia and moderate myopia (LM/MM), and 35 with SHM. The area under the log CSF curve (AULCSF) and the cut-off spatial frequency (Cut-off SF) were employed as measures of CSF. Adaptive optics (AO) was employed to quantify the cone density, spacing, and regularity. The thickness and blood flow of the retinal sublayers were determined from vertical and horizontal optical coherence tomography angiography (OCTA) A-scans. Swept-source optical coherence tomography (SS-OCT) was employed to analyze the choroidal thickness (CT) and choroidal vascularity using a custom algorithm. Differences in the retinal and choroidal parameters, cone distribution, AULCSF, and Cut-off SF were compared among the three groups. Multivariate linear mixed models were used to elucidate the associations between photoreceptor morphological alterations, retinal and choroidal parameters, and AULCSF.ResultsThe AULCSF and Cut-off SF were significantly lower in the SHM group compared to the EM and LM groups (p < 0.05). The SHM group had less cone density, larger cone spacing, and lower cone regularity than the EM and LM/MM groups (p < 0.05). Moreover, the thickness of the inner segment of photoreceptors (IS), retinal pigment epithelium (RPE) layer and choroid were reduced, and the outer segment of photoreceptors (OS) was thicker in the SHM group compared to the EM and LM/MM groups (all p < 0.05). A longer axial length (AL) was correlated with decreased AULCSF, cone density, and cone spacing (r = −0.800 to 0.752, all p < 0.050). Additionally, decreased CSF was correlated with lower cone density (r = 0.338, p = 0.035).ConclusionDecreased contrast sensitivity was observed in patients with SHM and cone density was significantly correlated with reduced AUCSF

Bi-Functional Silica Nanoparticles Doped with Iron Oxide and CdTe Prepared by a Facile Method

Cadmium telluride (CdTe) and iron oxide nanoparticles doped silica nanospheres were prepared by a multistep method. Iron oxide nanoparticles were first coated with silica and then modified with amino group. Thereafter, CdTe nanoparticles were assembled on the particle surfaces by their strong interaction with amino group. Finally, an outer silica shell was deposited. The final products were characterized by X-ray powder diffraction, transmission electron microscopy, vibration sample magnetometer, photoluminescence spectra, Fourier transform infrared spectra (FT-IR), and fluorescent microscopy. The characterization results showed that the final nanomaterial possessed a saturation magnetization of about 5.8 emu g−1and an emission peak at 588 nm when the excitation wavelength fixed at 380 nm

Examining reasons for irresponsible driving and improving the effectiveness of road safety interventions through social marketing.

This dissertation aims to examine the factors influencing the young driver to commit the distracted driving behavior especially from the individual perspectives. After reviewing the literature, the main factors can be divided into three types which are the threatening advertisement, individual factors and the social influence. This study has applied qualitative research method to collect the data and the data was generated from in-depth interviews conducted with 12 UK residents who possess the current driver licenses. The previous studies have largely focused on examining the effectiveness of the threatening advertisement in order to prevent this kind of irresponsible driving behavior, while the effects of using fear appeals are contentious. However, according to the implication of the previous researches, the personality and the ability of self-regulation could be the important indicators in preventing the distracted driving behavior but both of them are not well examined. Therefore, this research is trying to fill the research gap with purposes to specifically investigate the influence of personality and self-regulation in the distracted driving. The main findings identified by this study are supported by the previous research. The driving behavior of the young people is affected by the application of fear appeals in advertisements, individual perspectives (level of the awareness, the ability of self-regulation), social norms (parents and peer passengers). In addition, it is worthy to mention that the personality is not a key component in affecting the driving behavior in terms of the individual perspectives. However, the level of awareness and the ability of self-regulation are important determinants affecting their choice while driving. The findings have opened new directions for future study which is to improve young drivers’ awareness by establishing correct perceptions of driving and the distracted driving instead of strongly stressing to use fear appeals. Finally, managerial implications and limitations are discussed

"Modeling and Applications of Spintronic Devices Based on Voltage Controlled Magnetic Anisotropy Effect"

Ph.DDOCTOR OF PHILOSOPHY (FOE

Voltage-input spintronic oscillator based on competing effect for extended oscillation regions (vol 125, 183902, 2019)

10.1063/1.5116611JOURNAL OF APPLIED PHYSICS126

Moving Low-Carbon Transportation in Xinjiang: Evidence from STIRPAT and Rigid Regression Models

With the rapid economic development of the Xinjiang Uygur Autonomous Region, the area’s transport sector has witnessed significant growth, which in turn has led to a large increase in carbon dioxide emissions. As such, calculating of the carbon footprint of Xinjiang’s transportation sector and probing the driving factors of carbon dioxide emissions are of great significance to the region’s energy conservation and environmental protection. This paper provides an account of the growth in the carbon emissions of Xinjiang’s transportation sector during the period from 1989 to 2012. We also analyze the transportation sector’s trends and historical evolution. Combined with the STIRPAT (Stochastic Impacts by Regression on Population, Affluence and Technology) model and ridge regression, this study further quantitatively analyzes the factors that influence the carbon emissions of Xinjiang’s transportation sector. The results indicate the following: (1) the total carbon emissions and per capita carbon emissions of Xinjiang’s transportation sector both continued to rise rapidly during this period; their average annual growth rates were 10.8% and 9.1%, respectively; (2) the carbon emissions of the transportation sector come mainly from the consumption of diesel and gasoline, which accounted for an average of 36.2% and 2.6% of carbon emissions, respectively; in addition, the overall carbon emission intensity of the transportation sector showed an “S”-pattern trend within the study period; (3) population density plays a dominant role in increasing carbon dioxide emissions. Population is then followed by per capita GDP and, finally, energy intensity. Cargo turnover has a more significant potential impact on and role in emission reduction than do private vehicles. This is because road freight is the primary form of transportation used across Xinjiang, and this form of transportation has low energy efficiency. These findings have important implications for future efforts to reduce the growth of transportation-based carbon dioxide emissions in Xinjiang and for any effort to construct low-carbon and sustainable environments