The Higgs (Amplitude) Mode in Ferromagnetic Metals

Note: Pizza served at 11:45 AM
Speaker: Kevin Bedell, Boston College

When: January 31, 2014 (Fri), 12:00PM to 01:00PM (add to my calendar)
Location: SCI 352
Hosted by: David Campbell

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract:

Using ferromagnetic Fermi liquid theory (FFLT), Bedell and Blagoev,* derived the collective low-energy excitations of a weak ferromagnet. They obtained the well-known magnon (Nambu-Goldstone) mode and found a new gapped mode that was never studied in weak ferromagnetic metals. We recently identified this mode as the Higgs (amplitude) mode of a ferromagnetic metal since it corresponds to a fluctuation of the amplitude of the order parameter and it propagates. We use the FFLT to describe the itinerant-electron ferromagnetic material MnSi. By fitting the model with the existing experimental results, we calculate the dynamical structure function and see well-defined peaks coming from the magnon and the Higgs. Our estimates of the relative intensity of the Higgs amplitude mode suggest that it can be seen in neutron scattering experiments on MnSi.

*Bedell and Blagoev, Phil. Mag. Lett. (2001)