4,705 research outputs found
Giant non-volatile electric field control of proximity induced magnetism in the spin-orbit semimetal SrIrO3
With its potential for drastically reduced operation power of information
processing devices, electric field control of magnetism has generated huge
research interest. Recently, novel perspectives offered by the inherently large
spin-orbit coupling of 5d transition metals have emerged. Here, we demonstrate
non-volatile electrical control of the proximity induced magnetism in SrIrO3
based back-gated heterostructures. We report up to a 700 % variation of the
anomalous Hall conductivity {\sigma}_AHE and Hall angle {\theta}_AHE as
function of the applied gate voltage Vg. In contrast, the Curie temperature TC
= 100K and magnetic anisotropy of the system remain essentially unaffected by
Vg indicating a robust ferromagnetic state in SrIrO3 which strongly hints to
gating-induced changes of the anomalous Berry curvature. The electric-field
induced ferroelectric-like state of SrTiO3 enables non-volatile switching
behavior of {\sigma}_AHE and {\theta}_AHE below 60 K. The large tunability of
this system, opens new avenues towards efficient electric-field manipulation of
magnetism.Comment: 13 pages, 5 figures, to be published in Advanced Functional Material
Direct Observation of Strong Anomalous Hall Effect and Proximity-induced Ferromagnetic State in SrIrO₃
The 5d iridium-based transition metal oxides have gained broad interest because of their strong spin-orbit coupling which favors new or exotic quantum electronic states. On the other hand, they rarely exhibit more mainstream orders like ferromagnetism due to generally weak electron-electron correlation strength. Here, we show a proximity-induced ferromagnetic (FM) state with TC ≈ 100 K and strong magnetocrystalline anisotropy in a SrIrO3 (SIO) heterostructure via interfacial charge transfer by using a ferromagnetic insulator in contact with SIO. Electrical transport allows to selectively probe the FM state of the SIO layer and the direct observation of a strong, intrinsic and positive anomalous Hall effect (AHE). For T ≤ 20 K, the AHE displays unusually large coercive and saturation field, a fingerprint of a strong pseudospin-lattice coupling. A Hall angle, σxyAHE/σxx, larger by an order of magnitude than in typical 3d metals and a FM net moment of about 0.1 μB/Ir, is reported. This emphasizes how efficiently the nontrivial topological band properties of SIO can be manipulated by structural modifications and the exchange interaction with 3d TMOs
Ultra high throughput sequencing excludes MDH1 as candidate gene for RP28-linked retinitis pigmentosa
PURPOSE: Mutations in IDH3B, an enzyme participating in the Krebs cycle, have recently been found to cause autosomal recessive retinitis pigmentosa (arRP). The MDH1 gene maps within the RP28 arRP linkage interval and encodes cytoplasmic malate dehydrogenase, an enzyme functionally related to IDH3B. As a proof of concept for candidate gene screening to be routinely performed by ultra high throughput sequencing (UHTs), we analyzed MDH1 in a patient from each of the two families described so far to show linkage between arRP and RP28.
METHODS: With genomic long-range PCR, we amplified all introns and exons of the MDH1 gene (23.4 kb). PCR products were then sequenced by short-read UHTs with no further processing. Computer-based mapping of the reads and mutation detection were performed by three independent software packages.
RESULTS: Despite the intrinsic complexity of human genome sequences, reads were easily mapped and analyzed, and all algorithms used provided the same results. The two patients were homozygous for all DNA variants identified in the region, which confirms previous linkage and homozygosity mapping results, but had different haplotypes, indicating genetic or allelic heterogeneity. None of the DNA changes detected could be associated with the disease.
CONCLUSIONS: The MDH1 gene is not the cause of RP28-linked arRP. Our experimental strategy shows that long-range genomic PCR followed by UHTs provides an excellent system to perform a thorough screening of candidate genes for hereditary retinal degeneration
Dual black holes in merger remnants. II: spin evolution and gravitational recoil
Using high resolution hydrodynamical simulations, we explore the spin
evolution of massive dual black holes orbiting inside a circumnuclear disc,
relic of a gas-rich galaxy merger. The black holes spiral inwards from
initially eccentric co or counter-rotating coplanar orbits relative to the
disc's rotation, and accrete gas that is carrying a net angular momentum. As
the black hole mass grows, its spin changes in strength and direction due to
its gravito-magnetic coupling with the small-scale accretion disc. We find that
the black hole spins loose memory of their initial orientation, as accretion
torques suffice to align the spins with the angular momentum of their orbit on
a short timescale (<1-2 Myr). A residual off-set in the spin direction relative
to the orbital angular momentum remains, at the level of <10 degrees for the
case of a cold disc, and <30 degrees for a warmer disc. Alignment in a cooler
disc is more effective due to the higher coherence of the accretion flow near
each black hole that reflects the large-scale coherence of the disc's rotation.
If the massive black holes coalesce preserving the spin directions set after
formation of a Keplerian binary, the relic black hole resulting from their
coalescence receives a relatively small gravitational recoil. The distribution
of recoil velocities inferred from a simulated sample of massive black hole
binaries has median <70 km/s much smaller than the median resulting from an
isotropic distribution of spins.Comment: 11 pages, 3 figures. Accepted for publication in MNRA
catena-Poly[[(ethanol-κO)[3-(1-phenyl-1H-pyrazol-3-yl)benzoic acid-κO]lithium]-μ-3-(1-phenyl-1H-pyrazol-3-yl)benzoato-κ2 O:O′]
The asymmetric unit of the title polymeric compound, [Li2(C16H11N2O2)2(C16H12N2O2)2(CH3CH2OH)2]n, contains two LiI ions, two 3-(1-phenyl-1H-pyrazol-3-yl)benzoate ions, two 3-(1-phenyl-1H-pyrazol-3-yl)benzoic acid molecules and two ethanol molecules. In the crystal structure, each of the two LiI ions has a distorted tetrahedral geometry, coordinated by two carboxylate O atoms, one carboxyl O atom and one ethanol O atom. The carboxylate group bridges the LiI ions, forming a one-dimensional polymeric chain along [100]. The crystal structure is further stabilized by O—H⋯O and C—H⋯N hydrogen bonding, and π–π interactions with centroid–centroid distances in the range 3.6534 (13)–3.8374 (13) Å
Constraining dark energy with gamma-ray bursts
We use the measurement of gamma-ray burst (GRB) distances to constrain dark
energy cosmological model parameters. We employ two methods for analyzing GRB
data - fitting luminosity relation of GRBs in each cosmology and using distance
measures computed from binned GRB data. Current GRB data alone cannot tightly
constrain cosmological parameters and allow for a wide range of dark energy
models.Comment: 27 pages, 12 figures, two methods of analysing GRB data, updated to
match published version
Use of contrast enhanced magnetic resonance angiography in assessment of anatomic suitability for renal denervation in the hypertensive population
Haldane-Hubbard Mott Insulator: From Tetrahedral Spin Crystal to Chiral Spin Liquid
Motivated by cold atom experiments on Chern insulators, we study the honeycomb lattice Haldane-Hubbard Mott insulator of spin-1/2 fermions using exact diagonalization and density matrix renormalization group methods. We show that this model exhibits various chiral magnetic orders including a wide regime of triple-Q tetrahedral order. Incorporating third-neighbor hopping frustrates and ultimately melts this tetrahedral spin crystal. From analyzing the low energy spectrum, many-body Chern numbers, entanglement spectra, and modular matrices, we identify the molten state as a chiral spin liquid (CSL) with gapped semion excitations. We formulate and study the Chern-Simons-Higgs field theory of the exotic CSL-to-tetrahedral spin crystallization transition
Distinct p21 requirements for regulating normal and self-reactive T cells through IFN-γ production.
Self/non-self discrimination characterizes immunity and allows responses against pathogens but not self-antigens. Understanding the principles that govern this process is essential for designing autoimmunity treatments. p21 is thought to attenuate autoreactivity by limiting T cell expansion. Here, we provide direct evidence for a p21 role in controlling autoimmune T cell autoreactivity without affecting normal T cellresponses. We studied C57BL/6, C57BL/6/lpr and MRL/lpr mice overexpressing p21 in T cells, and showed reduced autoreactivity and lymphadenopathy in C57BL/6/lpr, and reduced mortality in MRL/lpr mice. p21 inhibited effector/memory CD4(+) CD8(+) and CD4(-)CD8(-) lpr T cell accumulation without altering defective lpr apoptosis. This was mediated by a previously non-described p21 function in limiting T cell overactivation and overproduction of IFN-γ, a key lupus cytokine. p21 did not affect normal T cell responses, revealing differential p21 requirements for autoreactive and normal T cell activity regulation. The underlying concept of these findings suggests potential treatments for lupus and autoimmune lymphoproliferative syndrome, without compromising normal immunity.This work was supported by grants from the Ministry of Economy and Competitivity
(MINECO)/Instituto Carlos III (PI081835 PI11/00950) and the CAM (MITIC S2011/
BMD2502) to DB, and from the MINECO (SAF2010-21205 and PIB2010BZ-00564) and the CAM (MITIC S2011/BMD2502) to CMA.Peer reviewe
Strain‐Driven Bidirectional Spin Orientation Control in Epitaxial High Entropy Oxide Films
High entropy oxides (HEOs), based on the incorporation of multiple-principal cations into the crystal lattice, offer the possibility to explore previously inaccessible oxide compositions and unconventional properties. Here it is demonstrated that despite the chemical complexity of HEOs external stimuli, such as epitaxial strain, can selectively stabilize certain magneto-electronic states. Epitaxial (CoCrFeMnNi)O-HEO thin films are grown in three different strain states: tensile, compressive, and relaxed. A unique coexistence of rocksalt and spinel-HEO phases, which are fully coherent with no detectable chemical segregation, is revealed by transmission electron microscopy. This dual-phase coexistence appears as a universal phenomenon in (CoCrFeMnNi)O epitaxial films. Prominent changes in the magnetic anisotropy and domain structure highlight the strain-induced bidirectional control of magnetic properties in HEOs. When the films are relaxed, their magnetization behavior is isotropic, similar to that of bulk materials. However, under tensile strain, the hardness of the out-of-plane (OOP) axis increases significantly. On the other hand, compressive straining results in an easy OOP magnetization and a maze-like magnetic domain structure, indicating the perpendicular magnetic anisotropy. Generally, this study emphasizes the adaptability of the high entropy design strategy, which, when combined with coherent strain engineering, opens additional prospects for fine-tuning properties in oxides
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