Four-Year College Faculty-Student Team Fellowships Program
Christopher Stark is positioning a FePt:C sample for measurement in the alternating gradient force magnetometer.
During the summer of 2003, Prof. Paul Shand and student Christopher Stark from the University of Northern Iowa and Prof. Andrew Kunz and student Jason Levin-Koopman from Lawrence University were joining the MRSEC research team.
Paul worked with Diandra Leslie-Pelecky on the magnetic behavior of frozen spin systems, such as nanostructured GdAl2. Emphasis is on low-temperature blocking and interaction effects and their interpretation as spin-glas properties. One aim was to investigate the leading dipolar anisotropy and coercivity contribution of the Gd. Christopher worked with Dave Sellmyer and Minglang Yan on cluster-assembled materials. The aim of the research was to develop and investigate highly anisotropic fine-grained FePt materials for high-density magnetic recording. The project focused on using an alternating gradient force magnetometer (AGFM) to perform moment-decay measurements on thin-film FePt:C with various amounts of C and various annealing conditions. This relatively new technique allows us to estimate the stability parameter, the anisotropy constant, and the magnetic switching volume from a single set of measurements.
Student Jason Levin-Koopman and Prof. Andrew Kunz from Lawrence University
Andrew and Jason from Lawrence University were working with Evgeny Tsymbal and Sitaram Jaswal on micromagnetic and Monte Carlo simulations of nanoscale structures. They investigated the spin-dependent conductance of nine-atom nanocontacts connecting two large nickel electrodes with fcc atomic structure. This conductance is strongly correlated to the direction of the magnetization of both the junction and the electrodes. Calculating the conductance requires the knowledge of the equilibrium orientation of the atomic spins, particular in the nanocontact region. The magnetization in the nanocontact and electrodes was simulated using the Monte Carlo relaxation technique and assuming Heisenberg spins. The magnetization vector resulting from the relaxation calculation was then be used to calculate the conductance across the contact.
