다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

The article tells about the diversity of green spaces in London, the citizens’ attitude toward these spaces, and what Russian cities can learn from this experience.

Nature in London

Magnetic Weyl semimetals with broken time-reversal symmetry are expected to generate strong intrinsic anomalous Hall effects, due to their large Berry curvature. Here, we report a magnetic Weyl semimetal candidate, Co3Sn2S2, with a quasi-two-dimensional crystal structure consisting of stacked Kagome lattices. This lattice provides an excellent platform for hosting exotic topological quantum states. We observe a negative magnetoresistance that is consistent with the chiral anomaly expected from the presence of Weyl nodes close to the Fermi level. The anomalous Hall conductivity is robust against both increased temperature and charge conductivity, which corroborates the intrinsic Berry-curvature mechanism in momentum space. Owing to the low carrier density in this material and the significantly enhanced Berry curvature from its band structure, the anomalous Hall conductivity and the anomalous Hall angle simultaneously reach 1130 Ω-1 cm-1 and 20%, respectively, an order of magnitude larger than typical magnetic systems. Combining the Kagome-lattice structure and the out-of-plane ferromagnetic order of Co3Sn2S2, we expect that this material is an excellent candidate for observation of the quantum anomalous Hall state in the two-dimensional limit.

Giant anomalous Hall effect in a ferromagnetic Kagomé-lattice semimetal.

The origin of anomalous Hall effect (AHE) in magnetic materials is one of the most intriguing aspects in condensed matter physics and has been a controversial topic for a long time. Recent studies indicate that the intrinsic AHE is closely related to the Berry curvature of occupied electronic states. In a magnetic Weyl semimetal with broken time-reversal symmetry, there are significant contributions to Berry curvature around Weyl nodes, possibly leading to a large intrinsic AHE. Here, we report the quite large AHE in the half-metallic ferromagnet Co3Sn2S2 single crystal. By systematically mapping out the electronic structure of Co3Sn2S2 both theoretically and experimentally, we demonstrate that the intrinsic AHE from the Weyl fermions near the Fermi energy is dominating. The intrinsic anomalous Hall conductivity depends linearly on the magnetization and can be reproduced by theoretical simulation, in which the Weyl nodes monotonically move with the constrained magnetic moment on Co atom.

/pdf/large-intrinsic-anomalous-hall-effect-in-half-metallic-zh1laihrua.pdf

Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co 3 Sn 2 S 2 with magnetic Weyl fermions.

The magnetism of the ${M}_{n+1}A{X}_{n}$ phase, ${\text{Cr}}_{2}$GeC, and its Mn-doped system, (${\text{Cr}}_{1\ensuremath{-}x}$${\text{Mn}}_{x}$)${}_{2}$GeC ($x\ensuremath{\le}0.25$), synthesized via a solid state reaction, was investigated systematically. ${\text{Cr}}_{2}$GeC is in a spin-unpolarized state, but the ferromagnetic band polarization is induced immediately by the Mn doping. The Curie temperature, ${T}_{\mathrm{C}}$, and the spontaneous moment, ${p}_{\mathrm{s}}$, increase almost proportionally to the Mn concentration, strongly suggesting that ${\text{Cr}}_{2}$GeC is located in the vicinity of a ferromagnetic quantum critical point. The strong concentration dependence of ${p}_{\mathrm{eff}}/{p}_{\mathrm{s}}$, where ${p}_{\mathrm{eff}}$ is the effective moment in the paramagnetic state, indicates that the ferromagnetism appearing in the Mn-doped ${\text{Cr}}_{2}$GeC can be classified as a typical itinerant-electron ferromagnetism in a wide range of the degree of electron localization.

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/187045/1/PhysRevB.89.054435.pdf

Mn-doping-induced itinerant-electron ferromagnetism in Cr 2 GeC

The magnetization process of single crystals of the metallic kagome ferromagnet $\mathrm{C}{\mathrm{o}}_{3}\mathrm{S}{\mathrm{n}}_{2}{\mathrm{S}}_{2}$ was carefully measured via magnetization and ac susceptibility. Field-dependent anomalous transitions observed in low fields indicate the presence of an unconventional magnetic phase just below the Curie temperature, ${T}_{\mathrm{C}}$. The magnetic phase diagrams in low magnetic fields along different crystallographic directions were determined for the first time. The magnetic relaxation measurements at various frequencies covering five orders of magnitude from 0.01 to 1000 Hz indicate markedly slow spin dynamics only in the anomalous phase with characteristic relaxation times longer than 10 s.

Low-field anomalous magnetic phase in the kagome-lattice shandite C o 3 S n 2 S 2

We report on NMR and torque measurements on the frustrated quasi-two-dimensional spin-dimer system SrCu2(BO3)(2) in magnetic fields up to 34 T that reveal a sequence of magnetization plateaus at 1/8, 2/15, 1/6, and 1/4 of the saturation and two incommensurate phases below and above the 1/6 plateau The magnetic structures determined by NMR involve a stripe order of triplets in all plateaus, suggesting that the incommensurate phases originate from proliferation of domain walls We propose that the magnetization process of SrCu2(BO3)(2) is best described as an incomplete devil's staircase DOI: 101103/PhysRevLett110067210

Incomplete Devil's Staircase in the Magnetization Curve of SrCu 2 (BO 3 ) 2

We have synthesized a new spinel oxide ${\mathrm{LiRh}}_{2}{\mathrm{O}}_{4}$ with a mixed-valent configuration of ${\mathrm{Rh}}^{3+}$ and ${\mathrm{Rh}}^{4+}$. At room temperature, it is a paramagnetic metal, but on cooling, a metal-insulator transition occurs and a valence bond solid state is formed below 170 K. We argue that the formation of valence bond solid is promoted by a band Jahn-Teller transition at 230 K and the resultant confinement of ${t}_{2g}$ holes within the $xy$ band. The band Jahn-Teller instability is also responsible for the observed enhanced thermoelectric power in the orbital-disordered phase above 230 K.

Takeshi Waki

Papers

Mn-doping-induced itinerant-electron ferromagnetism in Cr 2 GeC

Low-field anomalous magnetic phase in the kagome-lattice shandite C o 3 S n 2 S 2

Incomplete Devil's Staircase in the Magnetization Curve of SrCu 2 (BO 3 ) 2

Band Jahn-Teller Instability and Formation of Valence Bond Solid in a Mixed-Valent Spinel Oxide LiRh 2 O 4

Single crystal growth and characterization of kagomé-lattice shandites Co3Sn2−xInxS2