Speaker:
Kevin Bedell
Institution:
Boston Coll.
Date:
Tuesday, March 18, 2014
Time:
2:30 pm
Location:
NS2 1201
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)
** Zhang, Farinas and Bedell, arXiv: 1305.4674 (2014)
** Zhang, Farinas and Bedell, arXiv: 1305.4674 (2014)
Host:
Sasha Chernyshev