Demonstration of 0-pi transition in Josephson junctions containing unbalanced synthetic antiferromagnets

Josephson junctions containing ferromagnetic (F) materials have been the subject of intense study over the past two decades. The ground state of such junctions oscillates between 0 and pi as the thickness of the ferromagnetic layer increases. For some applications, it might be beneficial to replace a very thin F layer with an unbalanced synthetic antiferromagnet (SAF) consisting of two F layers of different thicknesses whose magnetizations are coupled antiparallel to each other. According to theory, such a system should behave similarly to a single F layer whose thickness is equal to the difference of the two F-layer thicknesses in the SAF. We test that theoretical prediction with Josephson junctions containing unbalanced Ni/Ru/Ni SAFs, keeping the thickness of one layer fixed at 2.0 nm and varying the thickness of the other layer between 2.0 and 5.0 nm. We observe the first 0-pi transition at a thickness difference of 0.86 nm, which closely matches the position of the transition observed previously using single Ni layers.Comment: 6 pages, 3 figures. To be published in Applied Physics Letter

Effect of Co-60 gamma-ray irradiation on electrical properties of Ti/Au/GaAs1-xNx Schottky diodes

Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements at room temperature are used to study 50 kGy 60Co γ-ray electrical properties irradiation dependence of Ti/Au/GaAs1−xNx Schottky diodes with 0.2%; 0.4%; 0.8% and 1.2% nitrogen dilution. This γ-ray irradiation induces a permanent damage that has increased ideality factor and series resistance for all samples. It was accompanied by a decrease in Schottky barrier height with nitrogen content up to 0.4%N and remained constant thereafter. Radiation was also found to degrade the reverse leakage current. At high frequency (1 MHz), capacitance and conductance decreased after radiation due to a decrease in net doping concentration. Interface state density and series resistance were determined from C-V-f and G/ω-V-f characteristics using Hill-Coleman methods. Interface states density exponentially decreased with increasing frequency confirming the behavior of interface traps response to ac signal. Series resistance increases after irradiation is attributed to carrier's removal effect and mobility degradation. It has two peaks in the accumulation and inversion region for some diodes (0.4%N, 0.8%N). γ-ray irradiation produced traps levels and recombination centers that reduce relaxation time. An increase in %N content can impede irradiation damage with even some compensation when the percent of diluted nitrogen is high (1.2%N)

Pathways to a more peaceful and sustainable world:The transformative power of children in families

This article provides an overview of selected ongoing international efforts that have been inspired by Edward Zigler’s vision to improve programs and policies for young children and families in the United States. The efforts presented are in close alignment with three strategies articulated by Edward Zigler: (a) conduct research that will inform policy advocacy; (b) design, implement, and revise quality early child- hood development (ECD) programs; and (c) invest in building the next generation of scholars and advocates in child development. The intergenerational legacy left by Edward Zigler has had an impact on young children not only in the United States, but also across the globe. More needs to be done. We need to work together with a full commitment to ensure the optimal development of each child

Frequency and Temperature Dependent Interface States and Series Resistance in Au/SiO₂/<i>p</i>-Si (MIS) Diode

In this study, some electrical parameters of Au/SiO2/p-Si metal-insulator-semiconductor diode such as the barrier height and ideality factor and series resistance have been determined from the forward bias current-voltage characteristics in the temperature range 140-340 K. The capacitance-voltage and conductance-voltage characteristics of Au/SiO2/p-Si diode have been investigated over a wide frequency and temperature range of 3 kHz-1 MHz and 140-340 K, respectively. The experimental current voltage, capacitance-voltage and conductance-voltage characteristics of diode show frequency and temperature dependency. Also, the series resistance values of Au/SiO2/p-Si diode have been determined using capacitance-voltage characteristics. The density of interface states (N-ss) has been obtained from Hill-Coleman method. It has been determined that the series resistance (R-s) and the interface states (N-ss) decrease with increasing frequency

Analysis of interface states and series resistances in Au/p-InP structures prepared with photolithography technique

Some electronic parameters such as ideality factor, barrier height, series resistance and interface state densities of the Au/p-InP Schottky barrier diodes with 100 and 200 μm diameter contacts have been investigated. We have calculated electronic parameters of these two diodes and compared using experimental forward bias current-voltage (I-V) and reverse bias capacitance-voltage measurements at room temperature. The values of ideality factor and barrier height for the 100 and 200 μm diameter diodes have been obtained as 1.07, 0.84 and 1.08, 0.80 eV, respectively. In addition, we have calculated interface state density (N SS ) as a function of energy distribution (E SS -E V ) of these diodes and compared them. The energy distribution of interface states density has been determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. Density of interface states in the considered energy range are in close agreement with values obtained for 100 and 200 μm diameter Au/p-InP. © 2013 Indian Association for the Cultivation of Science

Origin of forward bias capacitance peak and intersection behavior of C and G/w of Ag/p-InP Schottky barrier diodes

Frequency-dependent electrical characteristics of Ag/p-InP diodes have been determined using impedance spectroscopy at room temperature. Series resistance (R,) and interface state(s) (N-ss) values were extracted from capacitance (C) and conductance (G/w) data using the Nicollian and Goetzberger and Hill-Coleman methods, respectively. C and G/w data were also corrected in the whole measured bias voltage range to obtain real diode capacitance C-c and conductance G(c) values in order to see the effects of R-s. Both the C-V and R-s-V plots showed anomalous peak in depletion region especially at low frequencies due to the existence of N-ss. C-V and G/w-V plots crossed at a certain bias voltage and this point shifted toward negative bias voltages with increasing frequency and then disappeared at 3 MHz. Also, decrease in C values corresponds to an increase in G/w values in the same bias voltages

Evaluation of lateral barrier height of inhomogeneous photolithography-fabricated Au/n-GaAs Schottky barrier diodes from 80 K to 320 K

In order to evaluate current conduction mechanism in the Au/n-GaAs Schottky barrier diode (SBD) some electrical parameters such as the zero-bias barrier height (BH) Phi(bo)(I-V) and ideality factor (n) were obtained from the forward bias current-voltage (I-V) characteristics in wide temperature range of 80-320 K by steps of 10K. By using the thermionic emission (TE) theory, the Phi(bo)(I-V) and n were found to depend strongly on temperature, and the n decreases with increasing temperature while the Phi(bo)(I-V) increases. The values of Phi(bo) and n ranged from 0.600 eV and 1.51(80 K) to 0.816 eV and 1.087 (320 K), respectively. Such behavior of Phi(bo) and n is attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution (GD) of BHs at Au/n-GaAs interface. In the calculations, the electrical parameters of the experimental forward bias I-V characteristics of the Au/n-GaAs SBD with the homogeneity in the 80-320 K range have been explained by means of the TE, considering GD of BH with linear bias dependence. (c) 2012 Elsevier Ltd. All rights reserved