Publications by authors named "Masahito Yoshizawa"

Low-temperature and elastic properties of the quasicrystal approximant GdCdhave been investigated by means of an ultrasonic measurement. Salient elastic anomalies were observed in the temperature and magnetic field dependence of the principal elastic constants, most probably being associated with the successive multiple magnetic phase transitions showing up at low temperatures. Based on the experimental data, a magnetic field vs temperature phase diagram was constructed.

View Article and Find Full Text PDF

We investigated the fundamental physical properties in the ultra-quantum limit state of bismuth through measurements of magnetoresistance, magnetization, magnetostriction, and ultrasound attenuation in magnetic fields up to 60T. For magnetic fields applied along the bisectrix direction of a single crystal, a drastic sign reversal in magnetostriction was observed at approximately 39T, which could be ascribed to the complete valley polarization in the electron Fermi pockets. The application of magnetic fields along the binary direction presented an anomalous feature at approximately 50T only in the magnetoresistance.

View Article and Find Full Text PDF

With decreasing temperature, liquids generally freeze into a solid state, losing entropy in the process. However, exceptions to this trend exist, such as quantum liquids, which may remain unfrozen down to absolute zero owing to strong quantum entanglement effects that stabilize a disordered state with zero entropy. Examples of such liquids include Bose-Einstein condensation of cold atoms, superconductivity, quantum Hall state of electron systems, and quantum spin liquid state in the frustrated magnets.

View Article and Find Full Text PDF

We verified the significance of 3-dimensional (3D) spectral mapping during atrial fibrillation (AFIB) using a 64-channel magnetocardiogram (MCG). The study consisted of 16 patients with valvular heart disease who had chronic AFIB. All 16 patients had surgical pulmonary vein (PV) isolation followed by valvular repair.

View Article and Find Full Text PDF

Background: QT dispersion reveals heterogeneities in the repolarization time in the three-dimensional (3D) structure of the ventricular myocardium. In this study, we report on a 3D function map of recovery time (RT) dispersions as measured by 64-channel magnetocardiography (MCG).

Methods: MCG were simultaneously recorded in 29 controls and 21 patients with previous myocardial infarction (MI).

View Article and Find Full Text PDF

Background: Magnetocardiography (MCG) has the potential for collecting three-dimensional (3D) intracardiac electric information, because the magnetic field is unaffected by the shape of the lungs and torso. In the present study, we report on the generation of a 3D heart outline and conduction pathway by means of a current density map using a 64-channel SQUID system, and an evaluation of its significance in patients with atrial flutter (AFL) and atrial fibrillation (AFIB).

Methods: The subjects consisted of 20 healthy volunteers, and 3 patients with AFL and 4 patients with AFIB.

View Article and Find Full Text PDF