Bulk Rotational Symmetry Breaking in Kondo Insulator SmB6

Kondo insulator samarium hexaboride (SmB6) has been intensely studied in recent years as a potential candidate of a strongly correlated topological insulator. One of the most exciting phenomena observed in SmB6 is the clear quantum oscillations appearing in magnetic torque at a low temperature despite the insulating behavior in resistance. These quantum oscillations show multiple frequencies and varied effective masses. The origin of quantum oscillation is, however, still under debate with evidence of both two-dimensional Fermi surfaces and three-dimensional Fermi surfaces. Here, we carry out angle-resolved torque magnetometry measurements in a magnetic field up to 45 T and a temperature range down to 40 mK. With the magnetic field rotated in the (010) plane, the quantum oscillation frequency of the strongest oscillation branch shows a four-fold rotational symmetry. However, in the angular dependence of the amplitude of the same branch, this four-fold symmetry is broken and, instead, a twofold symmetry shows up, which is consistent with the prediction of a two-dimensional Lifshitz-Kosevich model. No deviation of Lifshitz-Kosevich behavior is observed down to 40 mK. Our results suggest the existence of multiple light-mass surface states in SmB6, with their mobility significantly depending on the surface disorder level.Comment: 15 pages, 9 figure

Quantum Oscillations in Cux_xBi2_2Se3_3 in High Magnetic Fields

Cu$_x$Bi$_2$Se$_3$ has drawn much attention as the leading candidate to be the first topological superconductor and the realization of coveted Majorana particles in a condensed matter system. However, there has been increasing controversy about the nature of its superconducting phase. This study sheds light on present ambiguity in the normal state electronic state, by providing a complete look at the quantum oscillations in magnetization in Cu$_x$Bi$_2$Se$_3$ at intense high fields up to 31T. Our study focuses on the angular dependence of the quantum oscillation pattern in a low carrier concentration. As magnetic field tilts from along the crystalline c-axis to ab-plane, the change of the oscillation period follows the prediction of the ellipsoidal Fermi surface. As the doping level changes, the 3D Fermi surface is found to transform into quasi-cylindrical at high carrier density. Such a transition is potentially a Lifshitz transition of the electronic state in Cu$_x$Bi$_2$Se$_3$.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Rotational Symmetry Breaking in a Trigonal Superconductor Nb-Doped Bi₂Se₃

The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi2Se3) is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb)-doped Bi2Se3. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi2Se3

Averting Lemur Extinctions amid Madagascar\u27s Political Crisis

The most threatened mammal group on Earth, Madagascar’s five endemic lemur families (lemurs are found nowhere else), represent more than 20% of the world’s primate species and 30% of family-level diversity. This combination of diversity and uniqueness is unmatched by any other country—remarkable considering that Madagascar is only 1.3 to 2.9% the size of the Neotropics, Africa, or Asia, the other three landmasses where nonhuman primates occur. But lemurs face extinction risks driven by human disturbance of forest habitats. We discuss these challenges and reasons for hope in light of site-specific, local actions proposed in an emergency conservation action plan

Consumo e gênero: uma revisão da produção historiográfica recente sobre a América Latina no século XX

A partir de una revisión de la producción historiográfica reciente que estudia el siglo XX, este artículo muestra la relevancia del género para la construcción de una historia del consumo en América Latina. Con este objetivo, se enfoca el análisis en tres líneas de investigación que, desde una aproximación interseccional, aportan nuevas miradas y preguntas: la primera destaca la dimensión política del consumo, centrándose en la relación entre género y clase; la segunda aborda consumo y trabajo doméstico, señalando el vínculo entre género y nación; y la tercera analiza cultura material y corporalidades, destacando la articulación entre género y edad.Starting from a recent historiographical production’s revision studying the 20th Century, this article depicts the relevance of gender for the history of consumption-building in Latin America. Bearing that in mind, the analysis is geared to three researching lines, contributing with new perspectives and questions, as from an inter sectorial approach: the first one highlights the political dimension of consumption based upon the interaction between gender and class; the second addresses consumption and domestic work, displaying a link between gender and nation, and the third one analyses material culture and corporality emphasizing upon the articulation between gender and age.A partir de uma revisão da produção historiográfica recente que estuda o século XX, este artigo mostra a relevância do gênero para a construção de uma história do consumo na América Latina. Com esse objetivo, a análise está focada em três linhas de pesquisa que, sob uma aproximação interseccional, contribuem com novos olhares e perguntas: a primeira destaca a dimensão política do consumo e foca-se na relação gênero e classe; a segunda aborda consumo e trabalho doméstico, e sinaliza o vínculo entre gênero e nação; a terceira analisa cultura material e corporalidade, e destaca a articulação entre gênero e idade.Fil: Pérez, Inés. Universidad Nacional de Mar del Plata. Facultad de Humanidades. Departamento de Sociologia; Argentina. Universidad Nacional de Mar del Plata. Facultad de Humanidades. Departamento de Historia. Centro de Estudios Históricos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

What evidence exists on the links between natural climate solutions and climate change mitigation outcomes in subtropical and tropical terrestrial regions? A systematic map protocol

Background Natural climate solutions (NCS)—actions to conserve, restore, and modify natural and modified ecosystems to increase carbon storage or avoid greenhouse gas (GHG) emissions—are increasingly regarded as important pathways for climate change mitigation, while contributing to our global conservation efforts, overall planetary resilience, and sustainable development goals. Recently, projections posit that terrestrial-based NCS can potentially capture or avoid the emission of at least 11 Gt (gigatons) of carbon dioxide equivalent a year, or roughly encompassing one third of the emissions reductions needed to meet the Paris Climate Agreement goals by 2030. NCS interventions also purport to provide co-benefits such as improved productivity and livelihoods from sustainable natural resource management, protection of locally and culturally important natural areas, and downstream climate adaptation benefits. Attention on implementing NCS to address climate change across global and national agendas has grown—however, clear understanding of which types of NCS interventions have undergone substantial study versus those that require additional evidence is still lacking. This study aims to conduct a systematic map to collate and describe the current state, distribution, and methods used for evidence on the links between NCS interventions and climate change mitigation outcomes within tropical and sub-tropical terrestrial ecosystems. Results of this study can be used to inform program and policy design and highlight critical knowledge gaps where future evaluation, research, and syntheses are needed. Methods To develop this systematic map, we will search two bibliographic databases (including 11 indices) and 67 organization websites, backward citation chase from 39 existing evidence syntheses, and solicit information from key informants. All searches will be conducted in English and encompass subtropical and tropical terrestrial ecosystems (forests, grasslands, mangroves, agricultural areas). Search results will be screened at title and abstract, and full text levels, recording both the number of excluded articles and reasons for exclusion. Key meta-data from included articles will be coded and reported in a narrative review that will summarize trends in the evidence base, assess gaps in knowledge, and provide insights for policy, practice, and research. The data from this systematic map will be made open access