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A half-filled-band Hubbard model on an anisotropic triangular lattice (t in two bond directions and t ′ in the other) is studied using an optimization variational Monte Carlo method, to consider a Mott transition and superconductivity arising in κ-(BEDT-TTF)2X. Adopting wave functions with doublon-holon binding factors, we reveal that a first-order Mott (conductorto-nonmagnetic insulator) transition takes place at U = Uc, approximately of the bandwidth, for a wide t ′ /t range. This transition is not directly connected to magnetism. Robust d-wave superconductivity appears in a restricted parameter range: immediately below Uc and the moderate strength of frustration (0.4 < ∼ t ′ /t < ∼ 0.7), where short-range antiferromagnetic correlation sufficiently develops but does not come to a long-range order. The relevance to experiments is also discussed.

The nonequilibrium spin accumulation in ferromagnetic double barrier junctions is shown to govern the transport in small structures. Transport properties of such systems are described by a generalization of the theory of the Coulomb blockade. The spin accumulation enhances the magnetoresistance. The transient nonlinear transport properties are predicted to provide a unique experimental evidence of the spin accumulation in the form of a reversed current on time scales of the order of the spin-flip relaxation time. ͓S0163-1829͑99͒05302-3͔In the 1970s it was understood that electron transport in tunneling and heterostructures involving metallic ferromagnets is associated with nonequilibrium spins. 1,2 Compared to other time scales in electron transport the spin relaxation time is generally very long at low temperatures, being limited only by scattering at paramagnetic impurities and by spin-orbit scattering. The spin-relaxation time and the spindiffusion length which govern the spin accumulation has been measured by Johnson in polycrystalline gold films. 3 The concept of nonequilibrium spin accumulation plays an important role in the Boltzmann theory of transport of the giant magnetoresistance in the current perpendicular to the plane ͑CPP͒ configuration. 4,5 However, the experimental evidence for the spin accumulation is indirect at best. It can be shown that in the linear response regime the spin-and charge-distribution functions can be completely integrated out of the transport problem, which then depends exclusively on the scattering probabilities and the applied bias. 5 In this paper we show theoretically how unambiguous evidence for a nonequilibrium spin accumulation can be obtained by the dc and ac response of ferromagnetic double barrier junctions in the nonlinear regime. These junctions have to be small in order to observe large effects, which means that the complications of the Coulomb blockade have to be taken into account ͑for a review see Ref. 6͒. To this end we have to extend very recent theories of the Coulomb blockade in ferromagnetic double barrier junctions 7 to include time dependence and a nonzero spin relaxation time. 8 Ono et al. succeeded in fabricating a ferromagnetic single electron transistor, 9 which in principle can be used to test our predictions. Coulomb charging effects have also been seen in discontinuous multilayers 10 and in small cobalt clusters. 11 We first show that the spin accumulation in ferromagnetic double barrier junctions becomes relevant when the number of electrons in the island between the tunneling barriers is relatively small. In ferromagnetic structures where the tunneling rates depend on the electron spin, a finite current through the system is accompanied by a spin current out of or into the island (‫ץ‬s/‫ץ‬t) tr . This creates a nonequilibrium excess spin s on the island, which decays with the spin-flip relaxation time sf so that in steady state (‫ץ‬s/‫ץ‬t) tr ϭs/ sf . Energy relaxation is much faster than spin relaxation, so that the occupation of the states for...

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We study the origin of the intrinsic spin Hall conductivity (SHC) and the d-orbital Hall conductivity (OHC) in Pt based on a multiorbital tight-binding model with spin-orbit interaction. We find that the SHC exceeds 1000 e −1 ·Ω −1 cm −1 when the resistivity ρ is smaller than ∼ 10 µΩ cm, whereas it decreases to 300 e −1 · Ω −1 cm −1 when ρ ∼ 100 µΩ cm. In addition, the OHC is still larger than the SHC. The origin of the huge SHE and OHE in Pt is the large "effective magnetic flux" that is induced by the interorbital transition between dxy-and d x 2 −y 2 -orbitals with the aid of the strong spin-orbit interaction. PACS numbers:Recently, the spin Hall effect (SHE) has attracted much attention due to its fundamental interest and its potential application in spintronics. The SHE has a close relation to the anomalous Hall effect (AHE) in ferromagnets: In 1954, Karplus and Luttinger (KL) [1] studied the Hall effect in multiband systems and found that an electric field induces a spin-dependent transverse current in the presence of spin-orbit (SO) interaction. This effect causes the AHE (transverse charge current) in ferromagnetic metals and the SHE (transverse spin current) in paramagnetic metals. These phenomena are fundamental issues in recent condensed matter physics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In these years, great progress on the SHE in semiconductors has been made. Murakami et al. [2] and Sinova et al. [3] have studied the intrinsic (impurity-independent) SHE in semiconductors by developing the theory of KL. Now, the SHE in two-dimensional electron gas (2DEG) with a Rashba-type SO interaction is well understood [4][5][6][7]. Although the SHE in semiconductors was recognized by the optical detection of spin accumulation [8,9], it is unfortunately too small for quantitative analysis. Therefore, materials that show a large SHE are highly desirable.

Postoperative pulmonary complications (PPCs) after esophagectomy have been reported to occur in 15.9-30% of patients and lead to increased postoperative morbidity and mortality, prolonged duration of hospital stay, and additional medical costs. The purpose of this retrospective cohort study was to investigate the possible prevention of PPCs by intensive preoperative respiratory rehabilitation in esophageal cancer patients who underwent esophagectomy. The subjects included 100 patients (87 males and 13 females with mean age 66.5 ± 8.6 years) who underwent esophagectomy. They were divided into two groups: 63 patients (53 males and 10 females with mean age 67.4 ± 9.0 years) in the preoperative rehabilitation (PR) group and 37 patients (34 males and 3 females with mean age 65.0 ± 7.8 years) in the non-PR (NPR) group. The PR group received sufficient preoperative respiratory rehabilitation for >7 days, and the NPR group insufficiently received preoperative respiratory rehabilitation or none at all. The results of the logistic regression analysis and multivariate analysis to correct for all considerable confounding factors revealed the rates of PPCs of 6.4% and 24.3% in the PR group and NPR group, respectively. The PR group demonstrated a significantly less incidence rate of PPCs than the NPR group (odds ratio: 0.14, 95% confidential interval: 0.02~0.64). [Correction added after online publication 25 June 2012: confidence interval has been changed from -1.86~ -0.22] This study showed that the intensive preoperative respiratory rehabilitation reduced PPCs in esophageal cancer patients who underwent esophagectomy.

We calculate the electronic states of the Mn-doped semiconductors and show that resonant states are formed at the top of the down spin valence band due to magnetic impurities and that they give rise to a strong and long-ranged ferromagnetic coupling between Mn moments. We propose that the coupling of the resonant states, in addition to the intra-atomic exchange interaction between the resonant and nonbonding states, is the origin of the ferromagnetism of (Ga-Mn)As. The mechanism is thus called "double resonance." The resonant states bring about the spin-dependent resistivity to produce magnetoresistive properties in (Ga-Mn)As and their junctions.