Ultrafast phonon and spin dynamics studies in magnetic heterostructure systems

Abstract

Since the discovery of giant magnetoresistance (GMR), the spin of the electron has attracted significant interest in the field of microelectronics. Spintronics, which involves manipulating both quantum spin states of electrons and their charge states, promises a wide variety of applications in storage, logic and sensors. In order to integrate spintronic devices into conventional semiconductor technology, it will be necessary to obtain an enhanced understanding of both theory and experiment related to the rich phenomena associated with the spin degree freedom for electrons in ferromagnetic materials and semiconductors. Recent developments in epitaxial thin film growth techniques provide unique opportunities to carry out spin-related experiments wherein one may manipulate spin interactions by optical, electrical and magnetic methodologies. The basic thrust of this dissertation encompasses three major topics: 1) carrier and phonon ultrafast dynamics; 2) optically excited spin coherence in the diluted magnetic semiconductor (Ga,Mn)As system; and 3) variation in the magnetic properties of the Fe/NiO system as a function of the thickness of the ferromagnetic layer.