Realization of topological superconductors (TSCs) hosting Majorana fermions is a central challenge in condensed-matter physics. One approach is to use the superconducting proximity effect (SPE) in ...heterostructures, where a topological insulator contacted with a superconductor hosts an effective p-wave pairing by the penetration of Cooper pairs across the interface. However, this approach suffers a difficulty in accessing the topological interface buried deep beneath the surface. Here, we propose an alternative approach to realize topological superconductivity without SPE. In a Pb(111) thin film grown on TlBiSe
, we discover that the Dirac-cone state of substrate TlBiSe
migrates to the top surface of Pb film and obtains an energy gap below the superconducting transition temperature of Pb. This suggests that a Bardeen-Cooper-Schrieffer superconductor is converted into a TSC by the topological proximity effect. Our discovery opens a route to manipulate topological superconducting properties of materials.
The recent research on multiferroics has provided solid evidence that the breaking of inversion symmetry by spin order can induce ferroelectric polarization P. This type of multiferroics, called ...spin-driven ferroelectrics, often show a gigantic change in P on application of a magnetic field B. However, their polarization (<~0.1 μC cm(-2)) is much smaller than that in conventional ferroelectrics (typically several to several tens of μC cm(-2)). Here we show that the application of external pressure to a representative spin-driven ferroelectric, TbMnO3, causes a flop of P and leads to the highest P (≈ 1.0 μC cm(-2)) among spin-driven ferroelectrics ever reported. We explain this behaviour in terms of a pressure-induced magnetoelectric phase transition, based on the results of density functional simulations. In the high-pressure phase, the application of B further enhances P over 1.8 μC cm(-2). This value is nearly an order of magnitude larger than those ever reported in spin-driven ferroelectrics.
Using first-principles calculations, we study the microscopic origin of ferroelectricity (FE) induced by magnetic order in the orthorhombic HoMnO3. We obtain the largest ferroelectric polarization ...observed in the whole class of improper magnetic ferroelectrics to date. We find that the two proposed mechanisms for FE in multiferroics, lattice and electronic based, are simultaneously active in this compound: a large portion of the ferroelectric polarization arises due to quantum-mechanical effects of electron orbital polarization, in addition to the conventional polar atomic displacements. An interesting mechanism for switching the magnetoelectric domains by an electric field via a 180 degrees coherent rotation of Mn spins is also proposed.
Abstract
Antiferromagnetic (AF) topological materials offer a fertile ground to explore a variety of quantum phenomena such as axion magnetoelectric dynamics and chiral Majorana fermions. To realize ...such intriguing states, it is essential to establish a direct link between electronic states and topology in the AF phase, whereas this has been challenging because of the lack of a suitable materials platform. Here we report the experimental realization of the AF topological-insulator phase in NdBi. By using micro-focused angle-resolved photoemission spectroscopy, we discovered contrasting surface electronic states for two types of AF domains; the surface having the out-of-plane component in the AF-ordering vector displays Dirac-cone states with a gigantic energy gap, whereas the surface parallel to the AF-ordering vector hosts gapless Dirac states despite the time-reversal-symmetry breaking. The present results establish an essential role of combined symmetry to protect massless Dirac fermions under the presence of AF order and widen opportunities to realize exotic phenomena utilizing AF topological materials.
A method of fabricating multilayer focusing mirrors that can focus X-rays down to 10 nm or less was established in this study. The wavefront aberration induced by multilayer Kirkpatrick-Baez mirror ...optics was measured using a single grating interferometer at a photon energy of 9.1 keV at SPring-8 Angstrom Compact Free Electron Laser (SACLA), and the mirror shape was then directly corrected by employing a differential deposition method. The accuracies of these processes were carefully investigated, considering the accuracy required for diffraction-limited focusing. The wavefront produced by the corrected multilayer focusing mirrors was characterized again in the same manner, revealing that the root mean square of the wavefront aberration was improved from 2.7 (3.3) rad to 0.52 (0.82) rad in the vertical (horizontal) direction. A wave-optical simulator indicated that these wavefront-corrected multilayer focusing mirrors are capable of achieving sub-10-nm X-ray focusing.
We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on noncentrosymmetric Weyl semimetal candidate NbP, and determined the electronic states of both Nb- and ...P-terminated surfaces. We revealed a drastic difference in the Fermi-surface topology between two types of surfaces, whereas the Fermi arcs on both surfaces are likely terminated at the surface projection of the same bulk Weyl nodes. A comparison of the ARPES data with our first-principles band calculations suggests a notable difference in the electronic structure at the Nb-terminated surface between theory and experiment. The present result opens a platform for realizing exotic quantum phenomena arising from the unusual surface properties of Weyl semimetals.
The effect of the relative grain size
d/
D (
d: grain size,
D: wire diameter) on stress–strain characteristics was investigated in Cu–Al–Mn-based shape memory alloy (SMA) wires. The yield stress (
σ
...y), the work-hardening rate after yielding (d
σ
PE/d
ε) and the stress hysteresis (Δ
σ) in the wires with a random texture decrease with increasing
d/
D. The transformation strain (
ε
TS) and the maximum pseudoelastic strain
(
ε
PE
MAX
)
increase with increasing
d/
D. The effect of grain size on pseudoelastic behaviors can be clarified from the volume fraction of three-dimensionally constrained grains and the
σ
y, d
σ
PE/d
ε and Δ
σ increase proportionally with increasing (1
−
(
d/
D))
2 while the
ε
TS decreases proportionally with increasing (1
−
(
d/
D))
2. Consequently, the effect of grain size on the pseudoelastic behaviors can be expressed using the Taylor and inverse Schmid factors. The
σ
y and the
ε
TS for wires with a 〈1
1
0〉 fiber texture are larger and smaller than those for wires with a random texture, respectively.
The aim of this study was to investigate the influence of dietary fat sources and lysolecithin on growth performance, visceral organ size, and histological intestinal alterations in broiler chickens. ...Ninety-six 7-d-old male broiler chickens were assigned to 8 treatments in a 2×4 factorial arrangement of treatments with 2 levels of lysolecithin (0 and 145mg/kg) and 4 different fat sources poultry fat (PF), yellow grease from Kagoshima (YG1), yellow grease from Kashima (YG2), and yellow grease from Hachinohe (YG3). Each treatment had 4 replicates of 3 broiler chickens per cage until 49d of age. There was no difference in BW gain due to fat sources, lysolecithin, or lysolecithin×fat source interaction throughout the experiment. By feeding lysolecithin, feed efficiency increased (P<0.05) during the growth period of 7 to 21d of age, and the weights of the duodenum, ileum, and total intestine decreased (P<0.05). Intestinal villus height, villus area, and cell area were not different among treatment groups, except that ileal villus height tended to decrease and ileal cell area tended to increase (P=0.077) by feeding lysolecithin. Increased duodenal cell mitosis and decreased jejunal tunica muscularis thickness were observed (P<0.05) by feeding lysolecithin. Furthermore, on the villus apical surface, more protuberated cells, cell clusters, and deeper cells at the sites of recently exfoliated cells were observed by feeding lysolecithin. However, the protuberant cells were not different among treatment groups. The Integrated Fluorescence Density Values of Anti-Cluster of Differentiation 36 reaction in the jejunum were significantly greater in the lysolecithin-fed groups, except YG2. These results indicate that feeding lysolecithin improves feed efficiency during 7 to 21d of age regardless of the fat type, and causes epithelial hypertrophy.
•Feeding lysolecithin increased feed efficiency of broiler during 7–21d of age.•The epithelial cells show hypertrophy in broiler fed lysolecithin.•The CD36 reaction in jejunum of lysolecthin group show higher signal than control.•Fat source does not influenced the effects of lysolecithin.
Abstract
In vortex-like spin arrangements, multiple spins can combine into emergent multipole moments. Such multipole moments have broken space-inversion and time-reversal symmetries, and can ...therefore exhibit linear magnetoelectric (ME) activity. Three types of such multipole moments are known: toroidal; monopole; and quadrupole moments. So far, however, the ME activity of these multipole moments has only been established experimentally for the toroidal moment. Here we propose a magnetic square cupola cluster, in which four corner-sharing square-coordinated metal-ligand fragments form a noncoplanar buckled structure, as a promising structural unit that carries an ME-active multipole moment. We substantiate this idea by observing clear magnetodielectric signals associated with an antiferroic ME-active magnetic quadrupole order in the real material Ba(TiO)Cu
4
(PO
4
)
4
. The present result serves as a useful guide for exploring and designing new ME-active materials based on vortex-like spin arrangements.
Lactoferrin (LF) was identified as a milk protein in 1960. Large-scale manufacturing of bovine LF (bLF) was established more than 20 years ago. Using this commercially available material, research ...for bLF applications has advanced from basic studies to clinical studies, and bLF has been applied to commercial food products for the last 25 years. During this period, it was found that LF is digested by gastric pepsin to generate a multi-potent peptide, lactoferricin. It was also demonstrated that oral administration of bLF augments host protection against infections via antimicrobial action and immunomodulation of the host. In addition, researchers have demonstrated that oral administration of bLF prevents cancer development. In this review, we look back on 25 years of bLF research and development.
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