Abstract
Static stripe order is detrimental to superconductivity. Yet, it has been proposed that transverse stripe fluctuations may enhance the inter-stripe Josephson coupling and thus promote ...superconductivity. Direct experimental studies of stripe dynamics, however, remain difficult. From a strong-coupling perspective, transverse stripe fluctuations are realized in the form of dynamic “kinks”—sideways shifting stripe sections. Here, we show how modest uniaxial pressure tuning reorganizes directional kink alignment. Our starting point is La
1.88
Sr
0.12
CuO
4
where transverse kink ordering results in a rotation of stripe order away from the crystal axis. Application of mild uniaxial pressure changes the ordering pattern and pins the stripe order to the crystal axis. This reordering occurs at a much weaker pressure than that to detwin the stripe domains and suggests a rather weak transverse stripe stiffness. Weak spatial stiffness and transverse quantum fluctuations are likely key prerequisites for stripes to coexist with superconductivity.
The minimal ingredients to explain the essential physics of layered copper-oxide (cuprates) materials remains heavily debated. Effective low-energy single-band models of the copper-oxygen orbitals ...are widely used because there exists no strong experimental evidence supporting multi-band structures. Here, we report angle-resolved photoelectron spectroscopy experiments on La-based cuprates that provide direct observation of a two-band structure. This electronic structure, qualitatively consistent with density functional theory, is parametrised by a two-orbital (Formula: see text and Formula: see text) tight-binding model. We quantify the orbital hybridisation which provides an explanation for the Fermi surface topology and the proximity of the van-Hove singularity to the Fermi level. Our analysis leads to a unification of electronic hopping parameters for single-layer cuprates and we conclude that hybridisation, restraining d-wave pairing, is an important optimisation element for superconductivity.
Relativistic massless Dirac fermions can be probed with high-energy physics experiments, but appear also as low-energy quasi-particle excitations in electronic band structures. In condensed matter ...systems, their massless nature can be protected by crystal symmetries. Classification of such symmetry-protected relativistic band degeneracies has been fruitful, although many of the predicted quasi-particles still await their experimental discovery. Here we reveal, using angle-resolved photoemission spectroscopy, the existence of two-dimensional type-II Dirac fermions in the high-temperature superconductor La
Sr
CuO
. The Dirac point, constituting the crossing of Formula: see text and Formula: see text bands, is found approximately one electronvolt below the Fermi level (E
) and is protected by mirror symmetry. If spin-orbit coupling is considered, the Dirac point degeneracy is lifted and the bands acquire a topologically non-trivial character. In certain nickelate systems, band structure calculations suggest that the same type-II Dirac fermions can be realised near E
.
Screening for prostate cancer is burdened by a high rate of overdiagnosis. The most appropriate algorithm for population-based screening is unknown.
We invited 37,887 men who were 50 to 60 years of ...age to undergo regular prostate-specific antigen (PSA) screening. Participants with a PSA level of 3 ng per milliliter or higher underwent magnetic resonance imaging (MRI) of the prostate; one third of the participants were randomly assigned to a reference group that underwent systematic biopsy as well as targeted biopsy of suspicious lesions shown on MRI. The remaining participants were assigned to the experimental group and underwent MRI-targeted biopsy only. The primary outcome was clinically insignificant prostate cancer, defined as a Gleason score of 3+3. The secondary outcome was clinically significant prostate cancer, defined as a Gleason score of at least 3+4. Safety was also assessed.
Of the men who were invited to undergo screening, 17,980 (47%) participated in the trial. A total of 66 of the 11,986 participants in the experimental group (0.6%) received a diagnosis of clinically insignificant prostate cancer, as compared with 72 of 5994 participants (1.2%) in the reference group, a difference of -0.7 percentage points (95% confidence interval CI, -1.0 to -0.4; relative risk, 0.46; 95% CI, 0.33 to 0.64; P<0.001). The relative risk of clinically significant prostate cancer in the experimental group as compared with the reference group was 0.81 (95% CI, 0.60 to 1.1). Clinically significant cancer that was detected only by systematic biopsy was diagnosed in 10 participants in the reference group; all cases were of intermediate risk and involved mainly low-volume disease that was managed with active surveillance. Serious adverse events were rare (<0.1%) in the two groups.
The avoidance of systematic biopsy in favor of MRI-directed targeted biopsy for screening and early detection in persons with elevated PSA levels reduced the risk of overdiagnosis by half at the cost of delaying detection of intermediate-risk tumors in a small proportion of patients. (Funded by Karin and Christer Johansson's Foundation and others; GÖTEBORG-2 ISRCTN Registry number, ISRCTN94604465.).
Abstract
The magnetic ground states in highly ordered double perovskites LaSr
1−
x
Ca
x
NiReO
6
(
x
= 0.0, 0.5, 1.0) are studied in view of the Goodenough-Kanamori rules of superexchange ...interactions in this paper. In LaSrNiReO
6
, Ni and Re sublattices are found to exhibit curious magnetic states separately, but no long range magnetic ordering is achieved. The magnetic transition at ~255 K is identified with the independent Re sublattice magnetic ordering. Interestingly, the sublattice interactions are tuned by modifying the Ni-O-Re bond angles through Ca doping. Upon Ca doping, the Ni and Re sublattices start to display a ferrimagnetically ordered state at low temperature. The neutron powder diffraction data reveals long range ferrimagnetic ordering of the Ni and Re magnetic sublattices along the crystallographic
b-
axis. The transition temperature of the ferrimagnetic phase increases monotonically with increasing Ca concentration.
High-temperature superconductivity emerges from an un-conventional metallic state. This has stimulated strong efforts to understand exactly how Fermi liquids breakdown and evolve into an ...un-conventional metal. A fundamental question is how Fermi liquid quasiparticle excitations break down in momentum space. Here we show, using angle-resolved photoemission spectroscopy, that the Fermi liquid quasiparticle excitations of the overdoped superconducting cuprate La1.77 Sr0.23 CuO4 is highly anisotropic in momentum space. The quasiparticle scattering and residue behave differently along the Fermi surface and hence the Kadowaki-Wood's relation is not obeyed. This kind of Fermi liquid breakdown may apply to a wide range of strongly correlated metal systems where spin fluctuations are present.
Abstract
Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and ...electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe
$$_2$$
2
, being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation (
$$\mu ^+$$
μ
+
SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe
$$_2$$
2
. From high-resolution NPD the magnetic spin order at base-temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the
ab
-plane and AFM coupling along the
c
-axis. The value if the ordered magnetic Cr moment is established as
$$\mu _{\textrm{Cr}}= 2.36~\mu _{\textrm{B}}$$
μ
Cr
=
2.36
μ
B
. From detailed
$$\mu ^+$$
μ
+
SR measurements we observe an AFM ordering temperature
$$T_{\textrm{N}}\approx 125$$
T
N
≈
125
K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From
$$\mu ^+$$
μ
+
SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe
$$_2$$
2
in the 3D Heisenberg AFM universality class. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices. This suggests the possibility for a strong magnon–phonon coupling, similar to what has been previously observed in the closely related compound LiCrO
$$_2$$
2
.
Mucosal immunity has a pivotal role in protection from respiratory viral infections.1 The current authors have showed substantial protection from omicron infection by high concentrations of nasal ...mucosal SARS-CoV-2 WT spike immunoglobulin-A (M-IgA) over a 4-week screening period.2 A sharp increase in M-IgA concentrations following BA.1 or BA.2 breakthrough infection in triple vaccinated health-care workers was also observed.2 Here, we present follow-up data with prospectively collected omicron infection rates and systemic and mucosal antibody concentrations from the same cohort (appendix pp 7–9, 12–14). The association between M-IgA concentrations at the 75th percentile or higher at enrolment and a reduced risk of symptomatic BA.1, BA.2, or BA.5 breakthrough infection remained over an 8-month follow-up period, with a hazard ratio (HR) of 0·55 (95% CI 0·35–0·87), much due to the initial risk difference (figure A). Serum WT spike-specific IgG (S-IgG) concentrations waned over 8 months following a third vaccine dose in all study participants (appendix p 10), concurrent with previous data.3 However, concentrations of nasal M-IgA in participants with previous SARS-CoV-2 infection, but without omicron breakthrough infection, remained above the amount associated to 65% protection2 over the 8-month study period (figure C).
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•Polymer solution of poly(vinylidene fluoride) in N,N-dimethylacetamide was used.•Ag and Zn containing fibrous materials were prepared by electrospinning method.•Ag and Zn ...nanoclusters were uniformly distributed in fibrous filter materials.•Ag and Zn nanoclusters containing material showed very high filtration efficiency.•Zn containing electrospun material showed very high antiviral activity against H1N1.
Nanowire poly(vinylidene fluoride) (PVDF) polymer membranes activated with Ag and Zn nanoclusters were prepared using the electrospinning method. The structure of membranes was varied by using different polymer concentrations in N,N-dimethylacetamide, electric field strength, and concentration of AgNO3 and ZnCl2 in an electrospinning solution. Materials synthesised were analysed by nitrogen sorption and mercury intrusion porosimetry, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, thermogravimetry, inductively coupled plasma mass spectroscopy, particle filtration efficiency, and pressure drop methods. The concentration of Ag and Zn nanoclusters in PVDF membranes was established and the influence on nanofibers activity has been discussed. The hydrophobicity of membranes was tested using the wetting (contact) angle measurement method. The human influenza A virus (IAV) A/WSN/1933 (H1N1) strain was used to evaluate the virucidal activity of filtration materials. The virucidal activity increased with Ag nanoclusters concentration in fibres. The most hydrophilic nanofibers with Zn nanoclusters showed very high and practically concentration independent virucidal activity that was two orders of magnitude higher compared to materials activated with Ag nanoclusters.
The quantum spin-liquid compound (C sub(4)H sub(12)N sub(2)) Cu sub(2)Cl sub(6) is studied by muon spin relaxation under hydrostatic pressures up to 23.6 kbar. At low temperatures, pressure-induced ...incommensurate magnetic order is detected beyond a quantum critical point at P sub(c) ~ 4.3 kbar. An additional phase transition to a different ordered phase is observed at P sub(1) ~ 13.4 kbar. The data indicate that the high-pressure phase may be a commensurate one. The established (P-T) phase diagram reveals the corresponding pressure-induced multicritical point at P sub(1), T sub(1) = 2.0 K.
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