Large magnetoresistance using hybrid spin filter devices

A magnetic "spin filter" tunnel barrier, sandwiched between a non-magnetic metal and a magnetic metal, is used to create a new magnetoresistive tunnel device, somewhat analogous to an optical polarizer-analyzer configuration. The resistance of these trilayer structures depends on the relative magnetization orientation of the spin filter and the ferromagnetic electrode. The spin filtering in this configuration yields a previously unobserved magnetoresistance effect, exceeding 100%.Comment: 3.5 pages, 3 figures, submitted to Appl. Phys. Let

Putting the public back in behavioral public policy

Behavioral public policies are aimed at influencing the behavior of the public in a way that is advantageous for the public itself and within the law. Sanders, Snijders and Hallsworth (2018 , this issue) summarize the state of the art of this new field of study and introduce a number of challenges and opportunities for the time to come. We address an additional challenge that is present and central in all attempts to influence behavior, namely the public – the people that are the target of behavioral public policies. We review evidence revealing that people do not passively accept those influence attempts, but often show reactant responses. We propose that the Persuasion Knowledge Model provides a framework both to understand the reactions of the public and to facilitate communication between academic researchers and practitioners

Mach's Principle and Model for a Broken Symmetric Theory of Gravity

We investigate spontaneous symmetry breaking in a conformally invariant gravitational model. In particular, we use a conformally invariant scalar tensor theory as the vacuum sector of a gravitational model to examine the idea that gravitational coupling may be the result of a spontaneous symmetry breaking. In this model matter is taken to be coupled with a metric which is different but conformally related to the metric appearing explicitly in the vacuum sector. We show that after the spontaneous symmetry breaking the resulting theory is consistent with Mach's principle in the sense that inertial masses of particles have variable configurations in a cosmological context. Moreover, our analysis allows to construct a mechanism in which the resulting large vacuum energy density relaxes during evolution of the universe.Comment: 9 pages, no figure

Observation of band structure and density of states effects in Co-based magnetic tunnel junctions

Utilizing Co/Al$_2$O$_3$/Co magnetic tunnel junctions (MTJs) with Co electrodes of different crystalline phases, a clear relationship between electrode structure and junction transport properties is presented. For junctions with one fcc(111) textured and one polycrystalline (poly-phase and poly-directional) Co electrode, a strong asymmetry is observed in the magnetotransport properties, while when both electrodes are polycrystalline the magnetotransport is essentially symmetric. These observations are successfully explained within a model based on ballistic tunneling between the calculated band structures (DOS) of fcc-Co and hcp-Co.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

Direct observation of the barrier asymmetry in magnetic tunnel junctions

A photoconductance method has been used to study directly the barrier asymmetry in TaOx magnetic tunnel junctions. Due to optical electron-hole pair generation in the barrier itself and subsequent transport in the elec. field, the sign and magnitude of the barrier asymmetry can be detd. quite accurately. The reliability of the technique is demonstrated by the independence on the direction of illumination. The oxidn. time where the asymmetry becomes zero is found to coincide with a max. in the magnetoresistance ratio. This is argued to be due to the complete oxidn. of the barrier material, resulting in a sym. tunnel barrier. [on SciFinder (R)

Predicting disclosure and help-seeking in university students with psychosocial problems based on stigma and attitudes towards disclosure and help-seeking

Despite high prevalence of mental health problems among university students, there’s a gap between the need for help and the actual treatment received. This study investigated disclosure on distress and hazardous alcohol use and help-seeking behavior in a sample of 1,791 students of a Dutch university of applied sciences. Students’ perceived public and personal stigma, and attitudes towards disclosure and help-seeking were assessed as possible predictors of disclosure and help-seeking behavior. Results of the analysis of variance and logistic regression analysis indicated that perceived public and personal stigma did not predict disclosure and helpseeking behavior, but that attitudes towards disclosure and help-seeking did. Students with both distress and hazardous alcohol use have the least tendency to disclose their problems to family, friends or classmates, but at the same time they do tend to seek help. Disclosure and seeking help for mental health challenges are health promoting competencies that seem to need more attention in university students. Although further research needs to validate these findings, it is recommended to promote disclosure and help-seeking among students by investing in mental health literacy programs, to educate students about mental health issues, raise awareness on available mental health services and their potential benefits

Oxidation process of AlOx-based magnetic tunnel junctions studied by photoconductance

The oxidation process of Co/AlOx/Co magnetic tunnel junctions has been investigated by photoconductance, in addition to traditional transport measurements. The shape of the photoconductance curves is explained within the framework of a simple qualitative model, assuming an oxidation time dependent imbalance of the incident forward and reverse hot electron fluxes, as well as inelastic scattering processes in the oxide. Due to the large sensitivity of the technique, the presence of unoxidized Al beneath the barrier layer can be monitored very accurately. The disappearance of a negative contribution to the photocurrent indicates the complete oxidation of the barrier layer, which coincides with the maximum magnetoresistance. From a Fowler analysis, the barrier height is determined as a function of oxidation time. The observed disagreement of the effective barrier heights determined by this technique and those found by Simmons fits demonstrates the added value of photoconductance studies

Parsing and reflective printing, bidirectionally

Language designers usually need to implement parsers and printers. Despite being two intimately related programs, in practice they are often designed separately, and then need to be revised and kept consistent as the language evolves. It will be more convenient if the parser and printer can be unified and developed in one single program, with their consistency guaranteed automatically.Furthermore, in certain scenarios (like showing compiler optimisation results to the programmer), it is desirable to have a more powerful reflective printer that, when an abstract syntax tree corresponding to a piece of program text is modified, can reflect the modification to the program text while preserving layouts, comments, and syntactic sugar.To address these needs, we propose a domain-specific language BIYACC, whose programs denote both a parser and a reflective printer for an unambiguous context-free grammar. BIYACC is based on the theory of bidirectional transformations, which helps to guarantee by construction that the pairs of parsers and reflective printers generated by BIYACC are consistent. We show that BIYACC is capable of facilitating many tasks such as Pombrio and Krishnamurthi's "resugaring", simple refactoring, and language evolution.We would like to thank reviewers for their valuable comments. This work was partially supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research (A) No. 25240009