Tuesday, July 3, 2007, 2:00 pm — Small Seminar Room, Bldg. 510
We report results of inelastic neutron scattering experiments on bcc solid 4He. In the experiments, we studied the excitation spectrum of the solid, including the phonon branches and the recently discovered "optic-like" branch (Markovich et al., Phys. Rev. Lett.{88}, 195301(2002)). We were able to determine that the new "optic-like" branch has an intrinsic dispersion, hence it is a propagating mode. This excitation also couples to the usual phonons. In addition, in the new experiments we discovered another "optic-like" branch. The second "optic-like" branch is dispersionless, with an energy around 1 meV (~11K). This excitation does not seem to couple to phonons. Hence, the properties of the two "optic-like" branches seem different. Since one expects only 3 acoustic phonon branches in a monoatomic cubic crystal, these two new branches must represent some different type of excitations. Some potential interpretations, based on Path Integral Monte Carlo simulations, will be presented. (Pelleg et al. PRB 73, 180301(R) (2006)).
Hosted by: Ivan Bozovic
3769 | INT/EXT | Events Calendar
Not all computers/devices will add this event to your calendar automatically.
A calendar event file named "calendar.ics" will be placed in your downloads location. Depending on how your device/computer is configured, you may have to locate this file and double click on it to add the event to your calendar.
Event dates, times, and locations are subject to change. Event details will not be updated automatically once you add this event to your own calendar. Check the Lab's Events Calendar to ensure that you have the latest event information.