Spin-polarized transport phenomena and magnetism in artificial nanostructures

L.B. STEREN

Buenos Aires

Workshop; Workshop on Recent Developments in Complex Materials: Production and Characterization; 2005

Univ. Buenos Aires

Spin-polarized transport phenomena in artificial nanostructures had an important thrust more than a  decade ago when the giant magnetoresistance in metallic multilayers was discovered. The emerging technology, called spintronics, associated with these phenomena, is based on the spin degree of freedom of the electrons. An important effort is being made nowadays to integrate ferromagnetic materials with semiconductors. A large number of innovative devices based on hybrid heterostructures have been already proposed, i.e.: spin-FETs, spin-LEDs. However, three major challenges should be overcome to use the hybrid systems in large scale applications: injection, transport and detection of  spin-polarized carriers (SPC). One of the more important remaining problems to solve are the injection and the detection of polarized carriers in the semiconductors. Transport coherence inside the semiconductor along acceptable distances for the operation of devices has already been demonstrated. The injection of  SPC at room temperature continues to be a technological barrier to surmount. The simplest idea to inject SPC into a semiconductor is to put it in contact with a ferromagnetic metal . Two obstacles  make difficult the achievement of this idea: one of them is the problem of associating materials that are very different structurally and chemically, the other one is the impedance mismatch within the hybrid structure.  In this talk, I will discuss the different options proposed to overcome these difficulties. I will introduce theoretical models to put into evidence the problems cited before and present recent experimental results in the field.