To evaluate cardiac function using echocardiography in patients with stroke admitted to subacute rehabilitation units.Retrospective, cross-sectional study.A total of 750 consecutive patients with stroke who were admitted to a suburban rehabilitation hospital. Mean age 67.5 years (standard deviation (SD) 12.3 years). Mean time since stroke 36.7 days (SD 13.2 days).Patients were assessed using transthoracic echocardiography within 7 days of admission. The prevalence of echocardiographic abnormalities was analysed and compared between cerebral infarction and haemorrhage using the Mantel-Haenszel method controlled for age.Arrhythmias were found in 13.7% of the patients, 94.2% of whom had atrial fibrillation. Left atrial enlargement and left ventricular hypertrophy were found in 20.4% and 19.5% of all patients, respectively. Left ventricular asynergy was detected in 6.1% of all patients, but 47.8% of them had no history of myocardial infarction. Left ventricular ejection fraction was low in 12.2% of all patients. Abnormal rhythms and left atrial enlargement were significantly more frequent in patients with cerebral infarction than in those with cerebral haemorrhage (p < 0.01).The prevalence of cardiac problems is high among patients with subacute stroke regardless of a history of heart disease, and this should be taken into account when planning rehabilitation programmes.
We studied magnetic tunnel junctions (MTJs) with a MgO(001) barrier and metastable bcc Co3Mn(001) disordered alloy electrodes. A tunnel magnetoresistance (TMR) ratio was approximately 200%–250% observed at room temperature. We successfully observed the TMR ratio greater than 600% at 10 K which was higher than the past reported value of MgO-based MTJs with ultrathin bcc Co(001) electrodes. However, our experimental value was still much lower than the past theoretical prediction in bcc Co/MgO/Co(001) MTJs. We discuss some differences in the bulk band structure affecting the TMR effect for bcc Co and bcc Co3Mn.
Abstract Electric fields at interfaces exhibit useful phenomena, such as switching functions in transistors, through electron accumulations and/or electric dipole inductions. We find one potentially unique situation in a metal–dielectric interface in which the electric field is atomically inhomogeneous because of the strong electrostatic screening effect in metals. Such electric fields enable us to access electric quadrupoles of the electron shell. Here we show, by synchrotron X-ray absorption spectroscopy, electric field induction of magnetic dipole moments in a platinum monatomic layer placed on ferromagnetic iron. Our theoretical analysis indicates that electric quadrupole induction produces magnetic dipole moments and provides a large magnetic anisotropy change. In contrast with the inability of current designs to offer ultrahigh-density memory devices using electric-field-induced spin control, our findings enable a material design showing more than ten times larger anisotropy energy change for such a use and highlight a path in electric-field control of condensed matter.
Electric-field (EF) effects have been studied on magnetic anisotropy in the metallic surfaces Pt/Fe/Pt(0 0 1) and Pd/Fe/Pd(0 0 1) by means of the first-principles electronic structure calculation which employs the generalized gradient approximation. The variation of anisotropy energy with respect to the EF is found to be opposite to each other. The modulus rate of the variation is larger by a few factors in the Pt substrate than in the Pd one. These results agree qualitatively well with the available experimental data. The electronic structures are presented and the origins in EF effects are discussed along a line of the second perturbative fashion.
The dependency of magnetic anisotropy constant K u on the degree of order for L1 0 -ordered FeNi alloys and tetragonally ordered Fe 2 Ni 2 N alloys has been investigated using first-principles calculations with special quasi-random structure. The K u increases with increasing ordering parameter S for both alloys and the K u of Fe 2 Ni 2 N exceeds that of FeNi in the region above S = 0.5, and more than 1MJ/m 3 of K u can be expected when the S is 0.67 or higher, reaching more than 2 MJ/m 3 for fully ordered Fe 2 Ni 2 N. We also investigated the K u of tetragonally ordered Fe 2 Ni 2 N for the tetragonal distortion, and found that the K u is increased with in-plane compressive stain and reaches 2.2MJ/m 3 with a 1% compression of in-plane lattice parameter.
Magnetic materials with low Gilbert damping and low magnetization are necessary for the realization of faster or more energy-efficient spintronic devices based on spin-transfer-torque. Here, we report Gilbert damping in epitaxially grown equiatomic quaternary CoFeMnSi Heusler alloy films. The 10 nm-thick films show a saturation magnetization of M S = 630 emu cm−3 and a Gilbert damping constant of , which are relatively small values among transition metal ferromagnets, in addition to its soft magnetic properties. The physical origin of the relatively low damping and the possibility of a further reduction of α to the ultra-low damping regime ~10−4 are discussed in terms of the spin-gapless-like electronic structure and the effect of the chemical order computed from first principles.
