Microwave Response and Spin Waves in Superconducting Ferromagnets

Excitation of spin waves is considered in a superconducting ferromagnetic slab with the equilibrium magnetization both perpendicular and parallel to the surface. The surface impedance is calculated and its behavior near propagation thresholds is analyzed. Influence of non-zero magnetic induction at the surface is considered in various cases. The results provide a basis for investigation of materials with coexisting superconductivity and magnetism by microwave response measurements.Comment: 10 pages, 7 figure

Domain Walls in a Tetragonal Chiral p-Wave Superconductor

Domain walls in a tetragonal chiral p-wave superconductors with broken time reversal symmetry are analyzed in the framework of the Ginsburg-Landau theory. The energy and the jump of the magnetic induction on the wall were determined for different types of walls as functions of the parameters of the Ginzburg-Landau theory and orientation of the domain wall with respect to the crystallographic axes. We discuss implications of the analysis for $Sr_{2}RuO_{4}$, where no stray magnetic fields from domain walls were detected experimentally.Comment: 8 pages, 2 figure

The Influence of Leadership, Competence and Motivation on the Performance of Congregational Financial Management at Port Numbay Klassis

This study aims to analyze the influence of leadership, motivation, and competence on the performance of congregation financial management at the GKI Port Numbay Klassis. This study employed a quantitative approach with an explanatory design to investigate the impact of leadership, competence, and motivation on the performance of congregation financial managers in Klasis Port Numbay. Data were collected through surveys and interviews with 98 financial managers across 49 congregations, with cluster sampling used to represent the population. The analysis included validity, reliability, and classical assumption tests, followed by multiple regression analysis to determine each independent variable's influence on performance, individually and collectively. The research found that leadership, competence, and motivation play crucial roles in enhancing the performance of financial managers in the congregation at Klasis GKI Port Numbay. Effective leadership provides clear direction and motivation, leading to improved performance. High competence in skills, knowledge, and work attitude significantly contributes to the managers' ability to perform their tasks optimally. Additionally, strong motivation among financial managers is key to achieving set performance targets. Leadership, competence, and motivation significantly influence the performance of financial managers, highlighting their importance in ensuring efficient and effective financial management in a church setting

Severe Developmental B Lymphopoietic Defects in Foxp3-Deficient Mice are Refractory to Adoptive Regulatory T Cell Therapy

The role of Foxp3-expressing regulatory T (Treg) cells in tolerance and autoimmunity is well-established. However, although of considerable clinical interest, the role of Treg cells in the regulation of hematopoietic homeostasis remains poorly understood. Thus, we analysed B and T lymphopoiesis in the scurfy (Sf) mouse model of Treg cell deficiency. In these experiments, the near-complete block of B lymphopoiesis in the BM of adolescent Sf mice was attributed to autoimmune T cells. We could exclude a constitutive lympho-hematopoietic defect or a B cell-intrinsic function of Foxp3. Efficient B cell development in the BM early in ontogeny and pronounced extramedullary B lymphopoietic activity resulted in a peripheral pool of mature B cells in adolescent Sf mice. However, marginal zone B and B-1a cells were absent throughout ontogeny. Developmental B lymphopoietic defects largely correlated with defective thymopoiesis. Importantly, neonatal adoptive Treg cell therapy suppressed exacerbated production of inflammatory cytokines and restored thymopoiesis but was ineffective in recovering defective B lymphopoiesis, probably due to a failure to compensate production of stroma cell-derived IL-7 and CXCL12. Our observations on autoimmune-mediated incapacitation of the BM environment in Foxp3-deficient mice will have direct implications for the rational design of BM transplantation protocols for patients with severe genetic deficiencies in functional Foxp3+ Treg cells

The NACE – CPRS – IAM mapping: A tool to support climate risk analysis of financial portfolio using NGFS scenarios.

We propose a mapping from NACE codes of economic activities, into Climate Policy Relevant Sectors (CPRS) and into the variables of the process-based Integrated Assessment Models (IAM) used by the Network for Greening the Financial System (NGFS) to provide its climate scenarios. We discuss the classification of CPRS at the disaggregation level provided by CPRS Granular, which distinguishes across energy technologies (e.g. within transport, motor vehicles powered by combustion vs electric engines). Then, we describe the mapping of NACE 4-digit – CPRS Granular – IAM variables used in the scenarios of the NGFS. CPRS enable users to group the large number of NACE codes into few categories of climate transition risk. At this point, it is possible to identify for each NACE economic activity the most relevant IAM variable to use in the NGFS scenarios. This procedure enables the use of climate scenarios (e.g. NGFS) for climate-related financial disclosure and climate stress testing. The goal of this note, and of the proposed mapping is to support practitioners, financial supervisors, investors and academics in climate transition risk disclosure and climate transition risk assessment, providing a science-based, transparent and operational tool

Exchange Effects in the Invar Hardening: Fe0.65Ni0.35Fe_{0.65}Ni_{0.35} as a test case

An increase of the critical resolved shear stress of Invar alloys (Invar hardening) with a lowering temperature is explained. The effect is caused by a growth of the exchange interaction between dangling $d$-electron states of dislocation cores and paramagnetic obstacles (e.g., Ni atoms in FeNi alloys) which occurs below the Curie temperature. The spins of the two electrons align along the magnetization due to the exchange interaction with the surrounding atoms of the ferromagnetic. The exchange interaction between the dislocations and obstacles is enhanced in Invars due to a strong growth of the magnetic moments of atoms under the action of elastic strains near the dislocation cores. Parameters characterizing the exchange interaction are determined for the case of the Fe$_{0.65}$Ni$_{0.35}$ Invar. The influence of the internal magnetic field on the dislocation detachment from the obstacles is taken into account. The obtained temperature dependence of the critical resolved shear stress in the Fe$_{0.65}$Ni$_{0.35}$ Invar agrees well with the available experimental data. Experiments facilitating a further check of the theoretical model are suggested.Comment: 8 pages, 2 figure

Absence of Meissner State and Robust Ferromagnetism in the Superconducting State of UCoGe: Possible Evidence of Spontaneous Vortex State

We report ac magnetic susceptibility and dc magnetization measurements on the superconducting ferromagnet UCoGe (with superconducting and Curie temperatures of $T_{{\rm SC}} \sim 0.5$~K and $T_{{\rm Curie}} \sim 2.5$~K, respectively). In the normal, ferromagnetic state ($T_{{\rm SC}} < T < T_{{\rm Curie}}$), the magnetization curve exhibits a hysteresis loop similar to that of a regular itinerant ferromagnet. Upon lowering the temperature below $T_{{\rm SC}}$, the spontaneous magnetization is unchanged, but the hysteresis is markedly enhanced. Even deeply inside the superconducting state, ferromagnetism is not completely shielded, and there is no Meissner region, a magnetic field region of $H < H_{\rm c1}$ (a lower critical field). From these results, we suggest that UCoGe is the first material in which ferromagnetism robustly survives in the superconducting state and a spontaneous vortex state without the Meissner state is realized.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jp

Vibrating-coil magnetometry of the spin liquid properties of Tb2Ti2O7

We have explored the spin liquid state in Tb2Ti2O7 with vibrating coil magnetometry down to 0.04 K under magnetic fields up to 5 T. We observe magnetic history dependence below $T < 0.2$K reminiscent of the classical spin ice systems Ho2Ti2O7 and Dy2Ti2O7. The magnetic phase diagram inferred from the magnetization is essentially isotropic, without evidence of magnetization plateaux as anticipated for so-called quantum spin ice, predicted theoretically for [111] when quantum fluctuations renormalize the interactions. Instead, the magnetization for $T \ll T*$ agrees semi-quantitatively with the predictions of "all-in/all-out" (AIAO) antiferromagnetism. Taken together this suggests that the spin liquid state in Tb2Ti2O7 is akin to an incipient AIAO-antiferromagnet.Comment: accepted in Physical Review Letter

Guiding superconducting vortices by magnetic domain walls

We demonstrate a unique prospect for inducing anisotropic vortex pinning and manipulating the directional motion of vortices using the stripe domain patterns of a uniaxial magnetic film in a the superconducting/ferromagnetic hybrid. Our observations can be described by a model, which considers interactions between magnetic charges of vortices and surface magnetic charges of domains resulting in the enhanced pinning of vortices on domain walls.Comment: 12 pages, 6 figure

Limited emission reductions from fuel subsidy removal except in energy exporting regions

Hopes are high that removing fossil fuel subsidies could help to mitigate climate change by discouraging inefficient energy consumption and levelling the playing field for renewables1–3. In September 2016, the G20 countries re-affirmed their 2009 commitment (at the G20 Leaders’ Summit) to phase out fossil fuel subsidies4,5 and many national governments are using today’s low oil prices as an opportunity to do so6–9. In practical terms, this means abandoning policies that decrease the price of fossil fuels and electricity generated from fossil fuels to below normal market prices10,11. However, whether the removal of subsidies, even if implemented worldwide, would have a large impact on climate change mitigation has not been systematically explored. Here we show that fossil fuel subsidy removal would have a small impact on global energy demand and carbon dioxide emissions and would not increase renewable energy use by 2030. Subsidy removal would reduce the carbon price necessary to stabilize greenhouse gas concentration at 550 parts per million by only 2–12 per cent under low oil prices. Removing subsidies in most regions would deliver smaller emission reductions than the Paris Agreement (2015) climate pledges and in some regions global subsidy removal may actually lead to an increase in emissions, owing to either coal replacing subsidized oil and natural gas or natural-gas use shifting from subsidizing, energy-exporting regions to non-subsidizing, importing regions. Our results show that subsidy removal would result in the largest CO2 emission reductions in oil- and gas-exporting regions, where reductions would exceed their climate pledges and where subsidy removal would also affect fewer people below the poverty line than in lower-income regions