Planar Hall effect from the surface of topological insulators

A prominent feature of topological insulators (TIs) is the surface states comprising of spin-nondegenerate massless Dirac fermions. Recent technical advances have made it possible to address the surface transport properties of TI thin films by tuning the Fermi levels of both top and bottom surfaces. Here we report our discovery of a novel planar Hall effect (PHE) from the TI surface, which results from a hitherto-unknown resistivity anisotropy induced by an in-plane magnetic field. This effect is observed in dual-gated devices of bulk-insulating Bi2−x Sb x Te3 thin films, where the field-induced anisotropy presents a strong dependence on the gate voltage with a characteristic two-peak structure near the Dirac point. The origin of PHE is the peculiar time-reversal-breaking effect of an in-plane magnetic field, which anisotropically lifts the protection of surface Dirac fermions from backscattering. The observed PHE provides a useful tool to analyze and manipulate the topological protection of the TI surface

Youthful Internationalism in the Age of ‘Socialism in One Country’: Komsomol'tsy, Pioneers and ‘World Revolution’ in the Interwar Period

This article examines the complex and multifaceted engagement of young Soviet communists with the idea of revolutionary internationalism and international solidarity in the interwar period. In spite of the introduction of the official doctrine of ‘Socialism in One Country’ and the ritualization of internationalism in in the 1920s, youth activists continued to encounter the powerful charismatic idea of ‘world revolution’. Moscow’s central role in the Communist International and developments in Asia and Europe meant that the members of the Pioneer organization and the Komsomol had to engage with revolutionary events abroad through the official discourse as well as through their league’s practices. The article seeks to reveal the interplay and tensions between the Komsomol’s official rhetoric and policies concerning its leading role in the international communist youth movement and the idiosyncratic revolutionary identities and beliefs of young activists. By examining the shifting rhetoric and realities in expressions and enactments of international solidarity by young communists, the paper will question the potency of the idea of ‘revolutionary internationalism’ amongst the communist youth movement and its significance in the intergenerational discourse

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

Probucol ameliorates renal and metabolic sequelae of primary CoQ deficiency in Pdss2

Therapy of mitochondrial respiratory chain diseases is complicated by limited understanding of cellular mechanisms that cause the widely variable clinical findings. Here, we show that focal segmental glomerulopathy-like kidney disease in Pdss2 mutant animals with primary coenzyme Q (CoQ) deficiency is significantly ameliorated by oral treatment with probucol (1% w/w). Preventative effects in missense mutant mice are similar whether fed probucol from weaning or for 3 weeks prior to typical nephritis onset. Furthermore, treating symptomatic animals for 2 weeks with probucol significantly reduces albuminuria. Probucol has a more pronounced health benefit than high-dose CoQ(10) supplementation and uniquely restores CoQ(9) content in mutant kidney. Probucol substantially mitigates transcriptional alterations across many intermediary metabolic domains, including peroxisome proliferator-activated receptor (PPAR) pathway signaling. Probucol's beneficial effects on the renal and metabolic manifestations of Pdss2 disease occur despite modest induction of oxidant stress and appear independent of its hypolipidemic effects. Rather, decreased CoQ(9) content and altered PPAR pathway signaling appear, respectively, to orchestrate the glomerular and global metabolic consequences of primary CoQ deficiency, which are both preventable and treatable with oral probucol therapy