Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometre size and the fact that they can be moved by small current densities have opened a ...new paradigm for the manipulation of magnetization at the nanoscale. Chiral skyrmion structures have so far been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films, and under an external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral Néel internal structure, which we explain as due to the large strength of the Dzyaloshinskii-Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions.
The perspective that behavior is often driven by unconscious determinants has become widespread in social psychology. Bargh, Chen, and Burrows' (1996) famous study, in which participants unwittingly ...exposed to the stereotype of age walked slower when exiting the laboratory, was instrumental in defining this perspective. Here, we present two experiments aimed at replicating the original study. Despite the use of automated timing methods and a larger sample, our first experiment failed to show priming. Our second experiment was aimed at manipulating the beliefs of the experimenters: Half were led to think that participants would walk slower when primed congruently, and the other half was led to expect the opposite. Strikingly, we obtained a walking speed effect, but only when experimenters believed participants would indeed walk slower. This suggests that both priming and experimenters' expectations are instrumental in explaining the walking speed effect. Further, debriefing was suggestive of awareness of the primes. We conclude that unconscious behavioral priming is real, while real, involves mechanisms different from those typically assumed to cause the effect.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recently, spin-transfer torque magnetic random access memory (STT-MRAM) has been considered as a promising universal memory candidate for future memory and computing systems, thanks to its ...nonvolatility, high speed, low power, good endurance, and scalability. However, as technology scales down, STT-MRAM suffers from serious process variations and thermal fluctuations, which greatly degrade the performance and stability of STT-MRAM. In general, the optimization and robustness of STT-MRAM under process variations often require a hybrid design flow and multilevel codesign strategies. In this paper, we quantitatively analyze the impacts of process variations and thermal fluctuations on the STT-MRAM performances from physics, technology, and circuit design point of views. Based on the analyses, we found that readability is becoming the newest challenge for deeply scaled STT-MRAM due to the conflict between sensing margin and read disturbance. To deal with this problem, a novel reconfigurable design strategy from device, circuit, and architecture codesign perspective is then presented. Finally, a conceptual hybrid magnetic/CMOS design flow is also proposed for STT-MRAM in deeply scaled technology nodes.
Magnetic tunnel junctions (MTJs) composed of ferromagnetic layers with perpendicular magnetic anisotropy (PMA) are of great interest for achieving high-density nonvolatile memory and logic chips ...owing to its scalability potential together with high thermal stability. Recent progress has demonstrated a capacity for high-speed performance and low power consumption through current-induced magnetization switching. In this paper, we present a compact model of the CoFeB/MgO PMA MTJ, a system exhibiting the best tunnel magnetoresistance ratio and switching performance. It integrates the physical models of static, dynamic, and stochastic behaviors; many experimental parameters are directly included to improve the agreement of simulation with experimental measurements. Mixed simulation based on the 65-nm technology node of a magnetic flip-flop validates its relevance and efficiency for MTJ/CMOS memory and logic chip design.
Why do companies issue sukuk? Klein, Paul-Olivier; Weill, Laurent
Review of financial economics,
November 2016, Letnik:
31, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper investigates the determinants for firms to choose sukuk over conventional bond. We investigate the potential impact of information asymmetries through moral hazard and adverse selection to ...explain why firms prefer using sukuk. We perform logit regressions of the choice of debt type to determine which characteristics lead a firm to issue a sukuk rather than a bond. We use a dataset of sukuk and conventional bond issuances in Malaysia from 2004 to 2013. We find evidence of the influence of information asymmetries and adverse selection on the choice of the sukuk market.
Spin-transfer torque magnetic tunnel junction (MTJ) is a promising candidate for nonvolatile memories thanks to its high speed, low power, infinite endurance, and easy integration with CMOS circuits. ...However, a relatively high current flowing through an MTJ is always required by most of the switching mechanisms, which results in a high electric field in the MTJ and a significant self-heating effect. This may lead to the dielectric breakdown of the ultrathin (~1 nm) oxide barrier in the MTJ and cause functional errors of hybrid CMOS/MTJ circuits. This paper analyzes the physical mechanisms of time-dependent dielectric breakdown (TDDB) in an oxide barrier and proposes an SPICE-compact model of the MTJ. The simulation results show great consistency with the experimental measurements. This model can be used to execute a more realistic design according to the constraints obtained from simulation. The users can estimate the lifetime, the operation voltage margin, and the failure probability caused by TDDB in the MTJ-based circuits.
In the last few years, especially after the Brexit referendum and the 2016 U.S. elections, there has been a surge in academic interest for misinformation and disinformation. Social, cognitive, and ...political scientists' work on these phenomena has focused on two main aspects:
Individuals' (and by extension societies') vulnerability to misinformation;
Factors and interventions that can increase individuals' (and societies') resistance to misinformation.
In this article, we offer a critical review of the psychological research pertaining to these two aspects. Drawing on this review, we highlight an emerging tension in the relevant literature. Indeed, the current state of the art of the political misinformation literature reflects the combined operation of two opposing psychological constructs: excess gullibility on the one hand and excess vigilance on the other. We argue that this conceptualization is important in both advancing theories of individuals' and societies' vulnerability to misinformation and in designing prospective research programs. We conclude with proposing what, in our view, are the most promising avenues for future research in the field.
How sukuk shapes firm performance Klein, Paul‐Olivier; Weill, Laurent; Godlewski, Christophe J.
World economy,
March 2018, Letnik:
41, Številka:
3
Journal Article
Recenzirano
Odprti dostop
With the large expansion of Islamic finance in the recent years, sukuk, which are the Sharia‐compliant substitute to conventional bonds, are now becoming more prominent. The aim of this study was to ...examine the impact of sukuk issuance on firm performance. To do so, we analyse how stock market performance and operating performance (OP) are influenced by issuance of sukuk and bonds on a sample of Malaysian listed companies. We consider the short‐term and medium‐term stock market reaction through the computation of cumulative abnormal returns and buy‐and‐hold abnormal returns. We investigate the impact on OP by performing regressions and by calculating abnormal operating performance (AOP) so that we can compare how issuance affects similar firms. We find that sukuk issuance generates a negative stock market reaction both in the short term and in the medium term. We also find evidence that issuing sukuk hampers OP. The analysis of AOP shows that sukuk issuers have better performance than their matched bond issuers, but that sukuk contributes to reduce the gap in performance over time. Overall, our results support the view that sukuk issuance hampers stock market performance, but that it is not attributable to a signalling effect on the bad financial situation of the issuer. We interpret our findings as evidence of adverse selection taking place on the financed projects and agency problems stemming from the specific sukuk structuring with stock market investors more reluctant to invest in sukuk issuers.
Power issues have become a major problem of CMOS logic circuits as technology node shrinks below 90 nm. In order to overcome this limitation, emerging logic-in-memory architecture based on ...nonvolatile memories (NVMs) are being investigated. Spin transfer torque (STT) magnetic random access memory (MRAM) is considered one of the most promising NVMs thanks to its high speed, low power, good endurance, and 3-D back-end integration. This paper presents a novel magnetic full-adder (MFA) design based on perpendicular magnetic anisotropy (PMA) STT-MRAM. It provides advantageous power efficiency and die area compared with conventional CMOS-only full adder (FA). Transient simulations have been performed to validate this design by using an industrial CMOS 40 nm design kit and an accurate STT-MRAM compact model including physical models and experimental measurements.
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