43 research outputs found
Majorana Landau-level Raman spectroscopy
The unambiguous experimental detection of quantum spin liquids and, in particular, of the long-sought Kitaev quantum spin liquid (KQSL) with its Majorana fermion excitations remains an outstanding challenge. One of the major obstacles is the absence of signatures that definitively characterize this phase. Here, we propose the Landau levels known to form in the Majorana excitation spectrum of the KQSL when certain strain fields are applied as a direct signature of Majorana fermions with Dirac-like dispersion. In particular, we show that the Majorana Landau level quantization of strained films of the KQSL can be directly probed by Raman spectroscopy. Such experiments are feasible in thin films of α − RuCl 3 , which are a promising place to search for the KQSL
Optical conversion of pure spin currents in hybrid molecular devices
Carbon-based molecules offer unparalleled potential for THz and optical devices controlled by pure spin currents: a low-dissipation flow of electronic spins with no net charge displacement. However, the research so far has been focused on the electrical conversion of the spin imbalance, where molecular materials are used to mimic their crystalline counterparts. Here, we use spin currents to access the molecular dynamics and optical properties of a fullerene layer. The spin mixing conductance across Py/C60 interfaces is increased by 10% (5 × 1018 m−2) under optical irradiation. Measurements show up to a 30% higher light absorbance and a factor of 2 larger photoemission during spin pumping. We also observe a 0.15 THz slowdown and a narrowing of the vibrational peaks. The effects are attributed to changes in the non-radiative damping and energy transfer. This opens new research paths in hybrid magneto-molecular optoelectronics, and the optical detection of spin physics in these materials
Phase diagram of bismuth in the extreme quantum limit
Elemental bismuth provides a rare opportunity to explore the fate of a
three-dimensional gas of highly mobile electrons confined to their lowest
Landau level. Coulomb interaction, neglected in the band picture, is expected
to become significant in this extreme quantum limit with poorly understood
consequences. Here, we present a study of the angular-dependent Nernst effect
in bismuth, which establishes the existence of ultraquantum field scales on top
of its complex single-particle spectrum. Each time a Landau level crosses the
Fermi level, the Nernst response sharply peaks. All such peaks are resolved by
the experiment and their complex angular-dependence is in very good agreement
with the theory. Beyond the quantum limit, we resolve additional Nernst peaks
signaling a cascade of additional Landau sub-levels caused by electron
interaction
Transformation of spin information into large electrical signals via carbon nanotubes
Spin electronics (spintronics) exploits the magnetic nature of the electron,
and is commercially exploited in the spin valves of disc-drive read heads.
There is currently widespread interest in using industrially relevant
semiconductors in new types of spintronic devices based on the manipulation of
spins injected into a semiconducting channel between a spin-polarized source
and drain. However, the transformation of spin information into large
electrical signals is limited by spin relaxation such that the magnetoresistive
signals are below 1%. We overcome this long standing problem in spintronics by
demonstrating large magnetoresistance effects of 61% at 5 K in devices where
the non-magnetic channel is a multiwall carbon nanotube that spans a 1.5 micron
gap between epitaxial electrodes of the highly spin polarized manganite
La0.7Sr0.3MnO3. This improvement arises because the spin lifetime in nanotubes
is long due the small spin-orbit coupling of carbon, because the high nanotube
Fermi velocity permits the carrier dwell time to not significantly exceed this
spin lifetime, because the manganite remains highly spin polarized up to the
manganite-nanotube interface, and because the interfacial barrier is of an
appropriate height. We support these latter statements regarding the interface
using density functional theory calculations. The success of our experiments
with such chemically and geometrically different materials should inspire
adventure in materials selection for some future spintronicsComment: Content highly modified. New title, text, conclusions, figures and
references. New author include
Histological confirmation of breast cancer registration and self-reporting in England and Wales: a cohort study within the UK Collaborative Trial of Ovarian Cancer Screening
In research studies, accurate information of cancer diagnosis is crucial. In women with breast cancer (BC), we compare cancer registration (CR) in England/Wales and self-reporting with independent confirmation
Search for Higgs bosons of the Universal Extra Dimensions at the Large Hadron Collider
The Higgs sector of the Universal Extra Dimensions (UED) has a rather
involved setup. With one extra space dimension, the main ingredients to the
construct are the higher Kaluza-Klein (KK) excitations of the Standard Model
Higgs boson and the fifth components of the gauge fields which on
compactification appear as scalar degrees of freedom and can mix with the
former thus leading to physical KK-Higgs states of the scenario. In this work,
we explore in detail the phenomenology of such a Higgs sector of the UED with
the Large Hadron Collider (LHC) in focus. We work out relevant decay branching
fractions involving the KK-Higgs excitations. Possible production modes of the
KK-Higgs bosons are then discussed with an emphasis on their associated
production with the third generation KK-quarks and that under the cascade
decays of strongly interacting UED excitations which turn out to be the only
phenomenologically significant modes. It is pointed out that the collider
searches of such Higgs bosons face generic hardship due to soft end-products
which result from severe degeneracies in the masses of the involved excitations
in the minimal version of the UED (MUED). Generic implications of either
observing some or all of the KK-Higgs bosons at the LHC are discussed.Comment: 25 pages, 9 figures and 1 tabl
Functional insights into the infective larval stage of Anisakis simplex s.s., Anisakis pegreffii and their hybrids based on gene expression patterns
List of species and specimen used in the phylogenetic tree of Additional file 1. Code of the voucher specimen and accession number for mitochondrial gene COII (*: sequences obtained from GenBank). Labeled are the specimens selected for RNA sequencing (first number, population; second number specimen). A. simplex s.s. – A. pegreffii refers to hybrids haplotype according Abollo et al. [23]. (DOCX 47 kb
Diabetic ketoacidosis
Diabetic ketoacidosis (DKA) is the most common acute hyperglycaemic emergency in people with diabetes mellitus. A diagnosis of DKA is confirmed when all of the three criteria are present — ‘D’, either elevated blood glucose levels or a family history of diabetes mellitus; ‘K’, the presence of high urinary or blood ketoacids; and ‘A’, a high anion gap metabolic acidosis. Early diagnosis and management are paramount to improve patient outcomes. The mainstays of treatment include restoration of circulating volume, insulin therapy, electrolyte replacement and treatment of any underlying precipitating event. Without optimal treatment, DKA remains a condition with appreciable, although largely preventable, morbidity and mortality. In this Primer, we discuss the epidemiology, pathogenesis, risk factors and diagnosis of DKA and provide practical recommendations for the management of DKA in adults and children
Space-time geometry of topological phases
The 2 + 1 dimensional lattice models of Levin and Wen (2005) [1] provide the most general known microscopic construction of topological phases of matter. Based heavily on the mathematical structure of category theory, many of the special properties of these models are not obvious. In the current paper, we present a geometrical space-time picture of the partition function of the Levin-Wen models which can be described as doubles (two copies with opposite chiralities) of underlying anyon theories. Our space-time picture describes the partition function as a knot invariant of a complicated link, where both the lattice variables of the microscopic Levin-Wen model and the terms of the Hamiltonian are represented as labeled strings of this link. This complicated link, previously studied in the mathematical literature, and known as Chain-Mail, can be related directly to known topological invariants of 3-manifolds such as the so-called Turaev-Viro invariant and the Witten-Reshitikhin-Turaev invariant. We further consider quasi-particle excitations of the Levin-Wen models and we see how they can be understood by adding additional strings to the Chain-Mail link representing quasi-particle world-lines. Our construction gives particularly important new insight into how a doubled theory arises from these microscopic models. © 2010 Elsevier Inc