Spin dependent tunneling devices for data storage applications

The demand for data storage solutions with ever increasing density has been motivating the development of advanced magnetoresistive (MR) materials and devices. Spin dependent tunneling (SDT) devices, which represent the latest advancements in magnetoresistive technologies, have been studied theoretically and experimentally in this dissertation. Significant and original contributions have been made to the technological advancements of SDT devices for potential data storage applications as well as the understanding of fundamentals of magneto-transport properties in SDT junctions.; The approaches to improve the figure of merit {dollar}(Delta R/R)/Hsb{lcub}sat{rcub}{dollar} and other properties of SDT devices have been emphasized. The interlayer coupling, which is mainly contributed by roughness-induced topological coupling, can be reduced by manipulating the interface roughness profile. The MR ratio can be improved by high quality tunneling barriers. Ultrathin oxide barriers with a low pinhole density and a high dielectric strength can be obtained by a plasma oxidation process.; A photo-lithographic process was developed to pattern SDT trilayers into SDT cells. The highest achievable MR at room temperature is 17.3% at a low field of 10-15Oe. A correlation between several technologically important parameters was observed. These parameters include the MR as well as temperature and voltage dependence of the MR and junction resistance.; A theory was proposed to successfully explain this correlation. The origin of this correlation is believed to be trap states in the tunneling barriers. Contributions of non-ideal tunneling processes via trap states are considered in addition to the ideal tunneling process. The trap states are believed to be related to the quality of the barrier, which is determined by preparation conditions. Approaches to improving the SDT junction properties for device applications are proposed.; Potential applications of SDT devices in magnetic recording were explored. A novel shielded read head design was proposed. The new sensor structure can dramatically enhance the head output by taking advantage of the design flexibility allowed by CPP mode in addition to desirable material properties. The output can be made independent of the track width. There are many other performance and processing advantages. The design is promising for magnetic recording at an areal density of 10Gb/in{dollar}sp2{dollar} and beyond.