Two-dimensional ferromagnetic superlattices

Mechanically exfoliated two-dimensional ferromagnetic materials (2D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature (T_C) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their T_C, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-T_C 2D FM Fe₃GeTe₂ (FGT) via A-type antiferromagnetic material CrSb (CS) which strongly couples to FGT. A superlattice structure of (FGT/CS)_n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism (XMCD) measurements, we have unequivocally discovered that T_C of 4-layer Fe₃GeTe₂ can be significantly enhanced from 140 K to 230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic CrSb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the T_C enhancement of the Fe₃GeTe₂ films, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, T_C can be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices.     

The role of lexical knowledge and related linguistic components in typical and poor language comprehenders of Chinese

The present study adapted the “Blueprint of the Reader” in comprehending language by Perfetti [2000, C. M. Brown & P. Hagoort. (Eds.), The neurocognition of language (pp. 167–208). Oxford, UK: Oxford University Press] as a framework for understanding Chinese language and reading comprehension in a group of 361 secondary Forms 1, 3 and 4 Cantonese-speaking Chinese students (mean age of 15 years) in Hong Kong. This framework with some modifications was tested with nine specially designed Chinese language and reading tasks with reasonably high reliability and surface validity. The main hypothesis was that lexical knowledge consisting of derivational morphology; correction of characters, words and sentences; segmentation of text into phrases and sentences; and writing to dictation should explain considerable individual variations, as shown in the English literature. This was tested with component analyses and multiple regression analyses. The total battery accounted for 66.80% of the variation while lexical knowledge alone explained 33.51% of the individual variation in the overall school performance in Chinese reading and writing. The second hypothesis was that subgroups of poor and good language and reading comprehenders in Chinese would be expected to show overlapping yet different component structures and their performance in the individual component tasks would be expected to differ as tested with analyses of variance. The results confirmed this hypothesis. Task analyses of the written protocols of essay writing and of morphological processing (prefixing and suffixing) provided insight into well-formed and poorly formed writing and word formation according to principles of Chinese psycholinguistics and yielded information for theory-based practice.     

Singaporean gifted adolescents under scrutiny: The gender factor

Research on the sex-role problems of gifted adolescents rarely lifts its sight beyond Western developed countries, making generalizations to the Third World suspect. The present study, by exploring the relationship between gender and adjustment among gifted adolescents in Singapore, hopes to extend the consideration of developmental sex-role issues to a society different from the West. Specifically, it reports that Singaporean gifted girls, like some of their Western counterparts, had difficulty in reconciling their giftedness with societal notions of femininity.Conceivably, this conflict placed them on the threshold of stress, leaving them more vulnerable than the gifted boys to adjustment problems. In addition, having internalized the gender stereotypic view that academic excellence was less important to them than to the boys, the gifted girls might inadvertently put ceilings on their own achievements. The paper concludes with several remedies for educators, counsellors, and parents to help gifted girls embark upon their road to self-fulfilment.

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Zusammenfassung Forschungen über die Probleme begabter Jugendlicher bezüglich geschlechtsspezifischer Rollen erfassen selten Zielgruppen außerhalb der entwickelten westlichen Länder. Demnach wird jede Übertragung auf die dritte Welt fragwürdig. Diese Studie beabsichtigt, mit einer Untersuchung über die Beziehungen zwischen Geschlecht und Anpassungsfähigkeit unter begabten Jugendlichen in Singapur, den Kontext der Debatte über entwicklungsbezogene geschlechtsspezifische Rollen auf eine nicht-westliche Gesellschaft zu erweitern. Insbesondere wird berichtet, daß begabte singapurische Mädchen es ebenso wie westliche Mädchen schwierig finden, ihre Begabtheit mit gesellschaftsüblichen Begriffen der Weiblichkeit zu vereinbaren. Es wäre durchaus möglich, daß dieser Konflikt sie bis an die Schwelle des Stresses bringt, so daß sie für Anpassungsprobleme anfälliger als begabte Jungen sind. Indem sie die geschlechtstypische Ansicht verinnerlichen, daß wissenschaftlicher Erfolg für sie weniger bedeutsam ist als für Jungen, könnten die begabten Mädchen ihren eigenen Leistungen unbewußt Grenzen setzen. Der Artikel endet mit verschiedenen Vorschlägen, wie Pädagogen, Berater und Eltern begabter Mädchen dazu beitragen könnten, daß diese Mädchen zu ihrer Selbsterfüllung finden.

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Résumé La recherche sur les problèmes liés au rôle des sexes des adolescents doués porte rarement son regard au-delà des pays industrialisés occidentaux, rendant les généralisations au Tiers Monde suspectes. En étudiant le rapport entre les sexes et l'adaptation chez les adolescents talentueux de Singapour, la présente étude espère étendre l'examen des problèmes de développement liés au rôle des sexes à une société différente de celles du monde occidental. En particulier, elle relate que les filles douées de Singapour, comme certaines de leurs homologues occidentales, ont des difficultés à concilier leur talent avec les notions sociales de fémininité. II est concevable que ce conflit les ait mises sous pression, les rendant ainsi plus vulnérables que les garçons doués aux problèmes d'adaptation. Par ailleurs, ayant assimilé le point de vue stéréotypé des sexes selon lequel l'excellence scolaire est moins importante pour elles que pour les garçons, il se peut que les filles douées fixent, par inadvertance, un plafond à leurs propres performances. Cet article conclut en proposant quelques remèdes aux éducateurs, conseillers et aux parents pour aider les filles capables à s'engager dans la voie qui leur permettra de s'accomplir.

     

The reciprocal relationship between motivation and self-regulation: A longitudinal study on academic performance

While previous studies have examined the single directional effects of motivation constructs in influencing students' use of self-regulatory strategies, few attempts have been made to unravel their interrelationship in a unified framework. In this study we adopt the social cognitive perspective and examine the reciprocal interplay between motivation and self-regulation constructs (as measured by the Learning and Study Strategies Inventory) in influencing academic performance. Based on two waves of measurements obtained from a large sample of undergraduates from a university in Hong Kong, a cross-lagged structural equation model identified significant reciprocal effects whereby students' self-regulation predicted their subsequent motivation. After controlling for prior academic achievement, student motivation was also found to be the strongest predictor of academic performance. The findings from this study have major implications for the importance placed on motivation and self-regulation as means of facilitating academic success.