High Spin-Torque Diode Sensitivity in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions Under DC Bias Currents
We report a large enhancement of spin-torque diode sensitivity in CoFeB/MgO/CoFeB magnetic tunnel junctions measured under perpendicular magnetic fields and dc bias currents. In the measurement of homodyne detection, a large dc output voltage of 190 μV was obtained when an RF signal power of -30 dB ·m and a dc current of +1.0 mA were applied. This value corresponds to the diode sensitivity of 190 mV/mW (260 mV/mW after impedance matching correction). The main origin of this enhancement is an offset of the damping torque and an increase in the precession angle induced by the spin-transfer torque due to the dc bias current application.
The study of patients with coronary artery disease by means of gated SPECT has been well established. One of the major limitations of this technique is the detection of myocardial perfusion defects in the presence of multivessel or three-vessel coronary artery disease due to balanced ischemia. Quantification of myocardial blood flow by positron emission tomography allows not only to study cardiac perfusion and function but also to determine the coronary flow reserve which has a better correlation with significant stenosis in patients with trivascular disease. The aim of this study was to demonstrate through a case report and literature review the importance of performing quantification of coronary blood flow in this group of patients.