مشخصات پژوهش

عنوان	Structure, magnetic properties and giant magnetoresistance of granular cobalt–silver films
نوع پژوهش	مقاله چاپ‌شده
کلیدواژه‌ها	Cobalt particle size, Magnetoresistance, Current density, Granular Co-Ag films, Coercivity, Magnetization, Crystalline structure, Magnetic structure, Superparamagnetic
چکیده	Co–Ag granular films were grown using electrodeposition technique. Atomic percentage, crystalline structure, morphological characterizations and magnetic structure of Co–Ag films were studied. Results confirm the simultaneous deposition of fcc–Ag and fcc–Co in the samples. It was found that percentage of Co in the composition of the Co–Ag film increases with the deposition current density. The granular nature of the Co–Ag films is evident by AFM micrographs. Also, magnetic force microscopy images show that magnetic structure of the all samples is composed of regular and uniform domains. The results show the magnetoresistance increases with increasing the deposition current density. Moreover, results indicated that the long-range magnetic structure with largest domain dimensions for Co–Ag films which are electrodeposited at the lowest deposition current densities leads to the lowest GMR value. The maximum value of giant magnetoresistance (GMR) is found to be 5.25% for Co–Ag films electrodeposited under current density of 12 mA/cm2. Thus, deposition conditions (e.g., applied current density) allow improving the GMR in granular Co–Ag films. The lowest AMR value is detected in the films with the highest GMR as the smallest particles are present. A zero-field-cooled magnetization measurement suggests that the ferromagnetic particle sizes with various diameters are dispersed in the Ag matrix. The Co particle size decreases with increasing the current density so that the magnetoresistance also increases. An analysis of the magnetotransport features reveal a high superparamagnetic contribution in all films. Studying the magnetic characteristics confirmed that an increase in a current density reduces the coercivity and the magnetization. This result suggests that exchange softening effect works effectively by the enhancement of the current density.
پژوهشگران	غلامرضا نبیونی (نفر دوم)، مریم ناصح نژاد (نفر اول)