Spin Coherence and Quantum Transport in Magnetic Nanostructures

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9701484 Samarth This experimental effort is aimed at understanding fundamental aspects of coherent electronic spin dynamics and spin-related transport in artificial quantum structures. Such investigations form the basis for the exploitation of coherent spin transport in future generations of magneto-electronic devices. The experiments focus on model nanostructures fabricated from II-VI magnetic semiconductors (MS), allowing one to systematically tailor spin interactions between confined electronic states and low dimensional distributions of local moments. The project is comprised of highly interactive efforts that combine the concurrent development of sophisticated MS nanostructures (digital magnetic heterostructures, magnetic two-dimensional electron gases (2DEGs), and quantum spin dots) with state-of-the- art spin dynamical probes having high temporal (~100 fs) and spatial (~100 nm) resolution (femtosecond Faraday rotation and time-resolved near-field scanning optical microscopy) and low- temperature magnetotransport. %%% Recent decades have witnessed the development of sophisticated solid state fabrication techniques that enable the construction of artificial atomic architectures ("nanostructures") in which one or more dimensions are at the nanoscale (a billionth the diameter of a human hair). There has also been a concurrent development of optical measurement techniques that allow one to record physical phenomena at unprecedently high speeds (ultrafast spectroscopy) and with very high spatial definition (near field microscopy). In this highly interactive project, we employ a powerful combination of state-of-the-art fabrication and measurement techniques to study the dynamic motion of electrons in new classes of "magnetic nanostructures," wherein magnetic atoms are embedded within an engineered semiconductor. These fundamental investigations lay the groundwork for future generations of magneto-electronic devices that would exploit the quantum mechani cal interactions between electrons and magnetic atoms for high-speed communication devices and ultra-high density memories. ***