UD Physics & Astronomy

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Current UG & G Majors: 166
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Colloquium Abstract

Date: April 9 (205 Gore Hall, 4:00pm)

Speaker: Dan Ralph, Physics Department, Cornell University

Title: Dynamics and Spectroscopy in Nanoscale Magnetic Devices

Abstract:

When a current of spin-polarized electrons interacts with a magnet, it can transfer spin angular momentum to the magnet and thereby apply a torque directly. Compared to using magnetic fields, this spin-transfer torque is a much more efficient was to manipulate the magnetic-moment direction of small magnets. I will describe the development of experiments to investigate the microscopic origin of this effect and to measure the ways in which individual nanomagnets respond to the spin torque, as well as potential applications.

I will also discuss progress toward extending experiments on spin-dependent transport and magnetic dynamics from the 100 nm scale of the spin-torque devices to smaller samples. My group has helped to develop a technique for using electromigration to form mechanically-stable nanoscale contacts, for use in single-molecule studies. Even for simple bare contacts (containing no molecules) made of permalloy or nickel, we find an unexpectedly large changes in resistance as a function of the angle of the magnetization. We propose that this effect is the result of quantum interference of electrons within the magnetic device.

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Colloquium Abstract