Investigation of the structure, magnetic and magnetoelastic properties of cobalt ferrite and its derivatives

In this research, cobalt ferrite thin films were deposited at 523 K which eliminates the need for annealing at higher temperatures and offers hope for integration of the thin films into micro-electromechanical devices.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of the structure, magnetic and magnetoelastic properties of cobalt ferrite and its derivatives

This study shows that the magnetostrictive properties of cobalt ferrite can be further enhanced by altering the oxygen content during preparation which resulted in the highest strain derivative reported for cobalt ferrite to date. Increase in annealing temperature before quenching the samples to ambient temperature resulted in changes in magnetic and magnetostrictive properties which were not accompanied by observable changes in crystal structure and microstructure. While the saturation magnetization increased, the anisotropy coefficient, coercive field, magnetostriction and strain derivative decreased. The changes show that annealing and quenching heat treatment resulted in cation redistribution between the tetrahedral and octahedral cation sites. Such redistribution can be exploited for property enhancement

Ultrahigh Sensitivity of Anomalous Hall Effect Sensor Based on Cr-Doped Bi2Te3 Topological Insulator Thin Films

Anomalous Hall effect (AHE) was recently discovered in magnetic element-doped topological insulators (TIs), which promises low power consumption and high efficiency spintronics and electronics. This discovery broadens the family of Hall sensors. In this paper, AHE sensors based on Cr-doped Bi2Te3 topological insulator thin films are studied with two thicknesses (15 and 65 nm). It is found, in both cases, that ultrahigh Hall sensitivity can be obtained in Cr-doped Bi2Te3. Hall sensitivity reaches 1666 Ω/T in the sensor with the 15 nm TI thin film, which is higher than that of the conventional semiconductor HE sensor. The AHE of 65 nm sensors is even stronger, which causes the sensitivity increasing to 2620 Ω/T. Furthermore, after comparing Cr-doped Bi2Te3 with the previously studied Mn-doped Bi2Te3 TI Hall sensor, the sensitivity of the present AHE sensor shows about 60 times higher in 65 nm sensors. The implementation of AHE sensors based on a magnetic-doped TI thin film indicates that the TIs are good candidates for ultrasensitive AHE sensors