FWI Institutskolloquium: "Beyond body scanners: How to use terahertz pulses to observe and control spin dynamics in solids"

Date

Apr 18, 2013

Time

10:30 AM - 12:00 PM

Speaker

Dr. Tobias Kampfrath, FHI Berlin

Language

en

Main Topic

Physik

Other Topics

Physik

Host

Susann Gebel (2345)

Description

Terahertz (THz) electromagnetic radiation has a wavelength of the order of 100µm and is located between the realms of electronics and optics. Besides its use in imaging and surveillance, THz radiation can also probe and even control many low-energy excitations such as phonons, excitons or Cooper pairs. This talk presents two applications of THz spectroscopy in the field of spin-based electronics (spintronics). First, we use the magnetic-field component of an intense THz pulse to start and stop a spin wave in the antiferromagnet NiO for only few precession cycles (corresponding to only few picoseconds). Such control may pave the way to an ultrafast switching of spin states. Second, a femtosecond laser pulse is employed to inject spin-polarized electrons from a ferromagnetic into a nonmagnetic metal. The resulting ultrafast spin current is detected through the inverse spin Hall effect that converts the spin flow into a measurable THz electromagnetic transient. Choosing nonmagnetic layers of different electron mobility allows us to manipulate the temporal shape of the spin current.

Last modified: Apr 18, 2013, 9:41:33 AM