Critical Exponents and Hall Effect in Iron- and Cobalt-based Metallic Glasses

A. ROSALES-RIVERA; J.C. HERNÁNDEZ-PARRA; J. LÓPEZ-TABARES; A. HINCAPIE-BEDOYA; A.A. VELÁSQUEZ-SALAZAR; D.F. GÓMEZ-MONTOYA; J. CHAVARRÍA-RUBIO; F. D. SACCONE

Barcelona

Conferencia; ICM 2015; 2015

In this work, we investigate the universality class and the Hall effect of three different metallic glasses, namely Fe70Nb10B20, (Fe50Co50)75Si5B20, and Co70Nb10B20. In so doing, we determined the critical exponents for the zero-field magnetization () and critical isotherm () and critical (Curie) temperatures (TC) from magnetization measurements. These metallic glasses were prepared as amorphous alloy ribbons by means of the melt spinning technique. The magnetization as a function of temperature of each sample was measured in the range 300 ? 950 K using a vibrating sample magnetometer (VSM-VersaLab by Quantum Design) at fixed external magnetic fields (H). The Hall effect measurements were carried out at room temperature for applied dc magnetic field and  dc electrical current varied in the range   ? 10 < H < 10 kOe and 10 < Idc < 50 mA, respectively. The present study shows that the magnetic features of Fe70Nb10B20 and (Fe50Co50)75Si5B20 are distinct in some aspects from the corresponding ones found in the soft magnetic metallic glass but less localized Co70Nb10B2. In fact, the universality class of the first two metallic glasses seems to correspond to the Ising model  = 0.33, while that in the latter seems to be more near with the Heisenberg model  = 0.42. The possible mechanisms leading to such universality classes including the spin-orbit interaction, shape anisotropies, direct exchange and itinerant exchange are analysed. The Hall effect experiments indicate that the extraordinary Hall contribution decreases more rapidly on Co70Nb10B2 as compared to (Fe50Co50)75Si5B20 and Fe70Nb10B20.