963 research outputs found
Fermi Surface Spin Texture and Topological Superconductivity in Spin-Orbit Free Non-Collinear Antiferromagnets
We explore the relationship among the magnetic ordering in real space, the
resulting spin texture on the Fermi surface, and the related superconducting
gap structure in non-collinear antiferromagnetic metals without spin-orbit
coupling. Via a perturbative approach, we show that a non-collinear magnetic
ordering in a metal can generate a momentum-dependent spin texture on its Fermi
surface, even in the absence of spin-orbit coupling, if the metal has more than
three sublattices in its magnetic unit cell. Thus, our theory naturally extends
the idea of altermagnetism to non-collinear spin structures. When
superconductivity is developed in a magnetic metal, as the gap-opening
condition is strongly constrained by the spin texture, the nodal structure of
the superconducting state is also enforced by the magnetism-induced spin
texture. Taking the non-collinear antiferromagnet on the kagome lattice as a
representative example, we demonstrate how the Fermi surface spin texture
induced by noncollinear antiferromagnetism naturally leads to odd-parity
spin-triplet superconductivity with nontrivial topological properties
Correlated normal state fermiology and topological superconductivity in UTe2
UTe2 is a promising candidate for spin-triplet superconductors, in which a
paramagnetic normal state becomes superconducting due to spin fluctuations. The
subsequent discovery of various unusual superconducting properties has promoted
the use of UTe2 as an exciting playground to study unconventional
superconductivity, but fathoming the normal state fermiology and its influence
on the superconductivity still requires further investigation. Here, we
theoretically show that electron correlation induces a dramatic change in the
normal state fermiology with an emergent correlated Fermi surface (FS) driven
by Kondo resonance at low temperatures. This emergent correlated FS can account
for various unconventional superconducting properties in a unified way. In
particular, the geometry of the correlated FS can naturally host topological
superconductivity in the presence of odd-parity pairings, which become the
leading instability due to strong ferromagnetic spin fluctuations. Moreover,
two pairs of odd-parity channels appear as accidentally degenerate solutions,
which can naturally explain the multicomponent superconductivity with broken
time-reversal symmetry. Interestingly, the resulting time-reversal breaking
superconducting state is a Weyl superconductor in which Weyl points migrate
along the correlated FS as the relative magnitude of nearly degenerate pairing
solutions varies. We believe that the correlated normal state fermiology we
discovered provides a unified platform to describe the unconventional
superconductivity in UTe2.Comment: 13 pages, 4 figures and 1 table in the main text, and 10 figures and
1 table in the Supplementary Informatio
Unveiling the Role of Ruthenium in Layered Sodium Cobaltite Toward High-Performance Electrode Enabled by Anionic and Cationic Redox
The effect of Ru substitution on the structure and electrochemical properties of P2-type Na0.67CoO2 is investigated. The first-discharge capacities of Na0.67CoO2 and Na0.6 [Co0.78Ru0.22]O2 materials are 128 and 163 mAh g−1 (23.5 mA g−1), respectively. Furthermore, the rate capability is improved due to the electro-conducting nature of Ru doping. Operando X-ray diffraction analysis reveals that the Na0.67CoO2 does not undergo a phase transition; however, multiple Na+/vacancy ordered superstructures within the P2 phase appear during Na+ extraction/insertion. In contrast, the Na0.6[Co0.78Ru0.22]O2 material undergoes a P2–OP4 phase transition during desodiation, with no formation of Na+/vacancy ordering within the P2 phase. The increased discharge capacity of Na0.6[Co0.78Ru0.22]O2 is most likely associated with additional cationic Ru4+/Ru5+ redox and increased anionic O2−/(O2n−) redox participation. Combined experimental (galvanostatic cycling, X-ray absorption spectroscopy, differential electrochemical mass spectrometry) and theoretical (density functional theory calculations) studies confirm that Ru substitution provokes the oxygen-redox reaction and that partial O2 release from the oxide lattice is the origin of the reaction. The findings provide new insight for improving the electrode performance of cathode materials via 4d Ru substitution and motivate the development of a new strategy for the design of high-capacity cathode materials for sodium-ion batteries.</p
Good Glycemic Control Is Associated with Better Survival in Diabetic Patients on Peritoneal Dialysis: A Prospective Observational Study
BACKGROUND: The effect of glycemic control after starting peritoneal dialysis (PD) on the survival of diabetic PD patients has largely been unexplored, especially in Asian population. METHODS: We conducted a prospective observational study, in which 140 incident PD patients with diabetes were recruited. Patients were divided into tertiles according to the means of quarterly HbA1C levels measured during the first year after starting PD. We examined the association between HbA1C and all-cause mortality using Cox proportional hazards models. RESULTS: The mean age was 58.7 years, 59.3% were male, and the mean follow-up duration was 3.5 years (range 0.4-9.5 years). The mean HbA1C levels were 6.3%, 7.1%, and 8.5% in the 1(st), 2(nd), and 3(rd) tertiles, respectively. Compared to the 1(st) tertile, the all-cause mortality rates were higher in the 2(nd) [hazard ratio (HR), 4.16; 95% confidence interval (CI), 0.91-18.94; p = 0.065] and significantly higher in the 3(rd) (HR, 13.16; 95% CI, 2.67-64.92; p = 0.002) tertiles (p for trend = 0.005), after adjusting for confounding factors. Cardiovascular mortality, however, did not differ significantly among the tertiles (p for trend = 0.682). In contrast, non-cardiovascular deaths, most of which were caused by infection, were more frequent in the 2(nd) (HR, 7.67; 95% CI, 0.68-86.37; p = 0.099) and the 3(rd) (HR, 51.24; 95% CI, 3.85-681.35; p = 0.003) tertiles than the 1(st) tertile (p for trend = 0.007). CONCLUSIONS: Poor glycemic control is associated with high mortality rates in diabetic PD patients, suggesting that better glycemic control may improve the outcomes of these patients
Laparoscopic Surgical Management and Clinical Characteristics of Ovarian Fibromas
Ovarian fibromas may be misdiagnosed as uterine myoma or ovarian malignant tumor. Laparoscopic examination appears to be an effective and safe surgical approach for managing ovarian fibromas
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