Spin-polarized light emitting diode using metal/insulator/semiconductor structures

We have succeeded in growing ferromagnetic metals (Co, Fe, and NiFe)/ Al2O3/ AlGaAs heterostructures with homogeneous and flat interfaces. The electro-luminescence (EL) from the light emitting diode (LED) consisting of the metal/insulator/semiconductor (MIS) structure depends on the magnetization direction of the ferromagnetic electrode at room temperature. This fact shows that a spin-injection from the ferromagnetic metal to the semiconductor is achieved. The spin-injection efficiency is estimated to be the order of 1 % at room temperature.Comment: 4 pages including 3 figure

Values for gender roles and relations among high school and non-high school adolescents in a Maya community in Chiapas, Mexico.

In the current study, I describe values for gender roles and cross-sex relations among adolescents growing up in a southern Mexican Maya community in which high school was introduced in 1999. A total of 80 adolescent girls and boys, half of whom were attending the new high school, provided their opinions on two ethnographically derived vignettes that depicted changes in gender roles and relations occurring in their community. Systematic coding revealed that adolescents not enrolled in high school tended to prioritise ascribed and complementary gender roles and emphasise the importance of family mediation in cross-sex relations. Adolescents who were enrolled in high school tended to prioritise equivalent and chosen gender roles, and emphasised personal responsibility and personal fulfillment in cross-sex relations. Perceptions of risks and opportunities differed by gender: girls favourably evaluated the expansion of adult female role options, but saw risks in personal negotiations of cross-sex relations; boys emphasised the loss of the female homemaker role, but favourably evaluated new opportunities for intimacy in cross-sex relations

Connecting Societal Change to Value Differences Across Generations: Adolescents, Mothers, and Grandmothers in a Maya Community in Southern Mexico

This study tests the hypothesis that societal change from subsistence agriculture to a market economy with higher levels of formal schooling leads to an increase in individualistic values that guide human development. Values relating to adolescent development and the transition to adulthood were compared across three generations of women in 18 families in the Maya community of Zinacantán in southern Mexico. Grandmothers grew up in Zinacantán when it was a farming community; mothers grew up during the introduction of commerce in the late 1970s and 1980s; daughters are now experiencing adolescence with an opportunity to attend high school in their community. Comparisons were also conducted between 40 female and male adolescents in high school and a matched sample of 40 adolescents who discontinued school after elementary. Values were measured using eight ethnographically derived social dilemmas about adolescent relationships with parents and peers, work and family gender roles, and sexuality and partnering. One character in the dilemmas advocates for interdependent values; a second character advocates for independent values. High school adolescents were more likely to endorse characters articulating independent values than non–high school adolescents, mothers, and grandmothers. Involvement in a market economy was also associated with higher levels of independent value endorsement in the mother and grandmother generations. Results suggest that the introduction of commerce drove value changes between grandmother and mother generations, and now schooling drives change. Qualitative examples of participants’ responses also illustrate how families negotiate shifting values

Societal Change and Values in Arab Communities in Israel: Intergenerational and Rural–Urban Comparisons

This study tested and extended Greenfield’s theory of social change and human development to adolescent development in Arab communities in Israel undergoing rapid social change. The theory views sociodemographic changes—such as contact with an ethnically diverse urban setting and spread of technology—as driving changes in cultural values. In one research design, we compared three generations, high school girls, their mothers, and their grandmothers, in their responses to value-assessment scenarios. In a second research design, we compared girls going to high school in an ethnically diverse city with girls going to school in a village. As predicted by the theory, a t test and ANOVA revealed that both urban life and membership in the youngest generation were significantly related to more individualistic and gender-egalitarian values. Regression analysis and a bootstrapping mediation analysis showed that the mechanism of change in both cases was possession of mobile technologies

Changing cultural pathways through gender role and sexual development: A theoretical framework

Greenfield's theory linking sociodemographic change to dynamic cultural values for family interdependence versus individual independence is applied to sexual and gender role socialization and development. The theory explains how cultural pathways for sexual and gender-role development transform in concert with sociodemographic changes: urbanization, formal schooling, capitalism, and communication technologies. As environments become more urban, commercial, and technological, with more opportunities for formal education, sexual development moves away from the ideals of procreation and family responsibility and toward the ideals of personal pleasure and personal responsibility. At the same time, gender-role development moves away from the ideals of complementary and ascribed gender roles and toward chosen and equal gender roles. We present psychological, anthropological, and sociological evidence for these trends in a variety of communities undergoing social and ecological change. © 2014 by the American Anthropological Association

Magnetic and superconducting properties on S-type single-crystal CeCu2_2Si2_2 probed by 63^{63}Cu nuclear magnetic resonance and nuclear quadrupole resonance

We have performed $^{63}$Cu nuclear magnetic resonance/nuclear quadrupole resonance measurements to investigate the magnetic and superconducting (SC) properties on a "superconductivity dominant" ($S$-type) single crystal of CeCu$_2$Si$_2$. Although the development of antiferromagnetic (AFM) fluctuations down to 1~K indicated that the AFM criticality was close, Korringa behavior was observed below 0.8~K, and no magnetic anomaly was observed above $T_{\rm c} \sim$ 0.6 K. These behaviors were expected in $S$-type CeCu$_2$Si$_2$. The temperature dependence of the nuclear spin-lattice relaxation rate $1/T_1$ at zero field was almost identical to that in the previous polycrystalline samples down to 130~mK, but the temperature dependence deviated downward below 120~mK. In fact, $1/T_1$ in the SC state could be fitted with the two-gap $s_{\pm}$-wave rather than the two-gap $s_{++}$-wave model down to 90~mK. Under magnetic fields, the spin susceptibility in both directions clearly decreased below $T_{\rm c}$, indicative of the formation of spin singlet pairing. The residual part of the spin susceptibility was understood by the field-induced residual density of states evaluated from $1/T_1T$, which was ascribed to the effect of the vortex cores. No magnetic anomaly was observed above the upper critical field $H_{c2}$, but the development of AFM fluctuations was observed, indicating that superconductivity was realized in strong AFM fluctuations.Comment: 10 pages, 8 figure

Spatially Inhomogeneous Superconducting State near Hc2H_{\rm c2} in UPd2_2Al3_3

We have performed $^{27}$Al-NMR measurements on single-crystalline UPd$_2$Al$_3$ with the field parallel to the $c$ axis to investigate the superconducting (SC) properties near the upper critical field of superconductivity $H_{\rm c2}$. The broadening of the NMR linewidth below 14~K indicates the appearance of the internal field at the Al site, which originates from the antiferromagnetically ordered moments of U 5$f$ electrons. In the SC state well below $\mu_0H_{\rm c2}$ = 3.4~T, the broadening of the NMR linewidth due to the SC diamagnetism and a decrease in the Knight shift are observed, which are well-understood by the framework of spin-singlet superconductivity. In contrast, the Knight shift does not change below $T_{\rm c}(H)$, and the NMR spectrum is broadened symmetrically in the SC state in the field range of 3~T $< \mu_0 H < \mu_0 H_{\rm c2}$. The unusual NMR spectrum near $H_{\rm c2}$ suggests that a spatially inhomogeneous SC state such as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state would be realized.Comment: 5 pages, 5 figure

Private message me s'il vous plait : Preferences for personal and masspersonal communications on Facebook among American and French students

Facebook, a social networking tool used worldwide, provides affordances for public/masspersonal and private/personal communication. Based on previous cross-cultural research demonstrating that masspersonal communication is adaptive in individualistic cultural contexts, we hypothesized that using Facebook to broadcast messages to one's entire network would be relatively more common and appealing to people in countries with greater individualistic values. To test this hypothesis, data were collected in two Western countries differing in levels of individualism, France (204 women, 47 men) and the U.S. (75 women, 89 men), through questionnaires measuring their Facebook use. Results indicated that American college students had larger Facebook networks and used both more masspersonal and personal communication with acquaintances compared to French college students. Masspersonal communication was mediated by network size. French students used more personal communication with friends than American students, but this association was not mediated by network size. These findings suggest that the appeal of masspersonal communication increases as a function of social network size, however, level of engagement in personal communication on Facebook is a function of other cultural differences between the U.S. and France, such as differences in individualistic values