RESUMO
Recent progress in magnetic tunnel junctions (MTJs) with a perpendicular easy axis consisting of CoFeB and MgO stacking structures has shown that magnetization dynamics are induced due to voltage-controlled magnetic anisotropy (VCMA), which will potentially lead to future low-power-consumption information technology. For manipulating magnetizations in MTJs by applying voltage, it is necessary to understand the coupled magnetization motion of two magnetic (recording and reference) layers. In this report, we focus on the magnetization motion of two magnetic layers in MTJs consisting of top layers with an in-plane easy axis and bottom layers with a perpendicular easy axis, both having perpendicular magnetic anisotropy. According to rectified voltage (Vrec) measurements, the amplitude of the magnetization motion depends on the initial angles of the magnetizations with respect to the VCMA direction. Our numerical simulations involving the micromagnetic method based on the Landau-Lifshitz-Gilbert equation of motion indicate that the magnetization motion in both layers is induced by a combination of VCMA and transferred angular momentum, even though the magnetic easy axes of the two layers are different. Our study will lead to the development of voltage-controlled MTJs having perpendicular magnetic anisotropy by controlling the initial angle between magnetizations and VCMA directions.
RESUMO
An 82-year-old woman underwent total gastrectomy for advanced gastric cancer with invasion to the lower esophagus. Her blood pressure dropped alarmingly during the operation, which was performed via the transabdominal and left-side transthoracic approach. Using echocardiography, we diagnosed intraoperative-onset reversible heart failure caused by ampulla cardiomyopathy. Because the infusion of catecholamines is associated with secondary heart failure, we gave her calcium antagonists and nicorandil, then started intra-aortic balloon pumping (IABP) and the percutaneous cardiopulmonary support system (PCPS). On postoperative day (POD) 7, the IABP and PCPS were removed and on POD 12, she was extubated successfully. The patient was discharged on POD 54 and has remained well. The factors predisposing her to ampulla cardiomyopathy were left-side thoracotomy, hypoxia caused by one-lung ventilation, and the infusion of high-dose catecholamines. Prompt diagnosis and timely treatment of the heart failure with IABP and PCPS prevented any further complications.
