Research

Spin Dynamics

What are the fundamental limits on how fast bits on a hard drive can be written? How do these limits depend on the size and shape of the bits and how the bits are magnetized? Our research in spin dynamics addresses questions like these. We use time-resolved ferromagnetic resonance microscopy to make movies of magnetic processes on time scales less than 100 picoseconds (or 0.1 billionths of a second). We are investigating the dynamics of thin films that are patterned into shapes with typical dimensions of a few microns across. We are adapting the time-resolved ferromagnetic resonance microscopy technique for the study of materials that become ferromagnetic at low temperature, including an unusual class of systems known as ferromagnetic semiconductors.   This project is supported by the National Science Foundation under Grant No. DMR-9983777.
Spin dynamics project page



Spin Transport

Semiconductors are widely used in electronic devices that process information, while magnetic materials are a fundamental element of storage technologies such as disk drives. Our research addresses the question of how semiconductors and magnetic materials can be combined in devices that will be capable of both storing and processing information. A critical step in implementing such a technology is transferring magnetic information from a conventional ferromagnet, such as iron, into a semiconductor. This project investigates spin transport across the ferromagnet-semiconductor interface and how spins introduced into a semiconductor can be manipulated and detected.  This work is supported by the Defense Advanced Research Project Agency and the Office of Naval Research.
Spin transport project page



Terahertz Spectroscopy

Light is a very useful tool for studying excitations in solids. However, many interesting excitations, including phonons and magnons, occur in the far infrared region of the spectrum (also known as the terahertz regime), where there is a shortage of intense pulsed radiation sources. This project, in collaboration with Prof. James Heyman's group at Macalester Colleges, investigates charge and spin dynamics in narrow band-gap semiconductor heterostructures using time-resolved terahertz spectroscopy.