Pulsed laser deposition (PLD) of magnetic multilayer and granular thin films

Abstract

CoAg granular and multilayer films as well as the Ti/Si based films have been fabricated by pulsed laser deposition (PLD) method. A special split target and a rotating multi-target holder have been developed to facilitate the PLD process. X-ray diffraction and Atomic Force Microscopy (AFM) were used to examine the structure and topography of the films respectively. The electrical properties and the magnetoresistance (MR) of these films were measured by a standard four-probe method. The effects of film thickness, substrate temperature and post-annealing on Ti/Si based films were investigated. In the CoAg granular films a MR ratio of 9% at 77 K and 5.5% at room temperature were obtained under the influence of a magnetic field of 1 Tesla. The PLD CoAg multilayer films in this work however showed a relatively poor MR. Some possible explanations for this result are suggested. Anomalous electrical properties were obtained in the Ti/Si based films. In addition, an unusual and rather large positive magnetoresistance (PMR) was also observed in these samples. Maximum PMR of +37% at about 170 K and +10% at room temperature were recorded. Thin films based on the Ti/Si and other related materials systems can have very good potentials for integrated sensor applications. It is one of the purpose of the present work to explore this material system and to report some of the interesting findings.