Browsing by Author "Demmel, F"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Collective high frequency motions in liquid deuterium fluoride
    (Oldenbourg Verlag, 2008-10) Demmel, F; Heusel, G; Waldner, I; Stride, JA; Bertagnolli, H
    The collective motions in liquid deuterium fluoride (DF) have been investigated by neutron scattering motivated by a MD simulation, which predicted an optic-type mode at small momentum transfers. Spectra of the measured longitudinal current correlation function show two modes. The lower frequency one originates from acoustic-type movements. The intensity of the higher frequency excitation can be attributed to an out of phase motion of neighboring DF molecules, an optic-type mode. Both, the frequencies and the intensity distribution in momentum space agree well with the MD simulation. The widths of the experimental spectra exceed the widths from the MD simulation and indicate missing relaxation processes in the simulation. © 2008, Oldenbourg Verlag
  • No Thumbnail Available
    Item
    Magnetic field splitting of the spin resonance in CeCoIn5
    (American Physical Society, 2012-10-17) Stock, C; Broholm, C; Zhao, Y; Demmel, F; Kang, HJ; Rule, KC; Petrovic, C
    Neutron scattering in strong magnetic fields is used to show the spin resonance in superconducting CeCoIn(5) (T(c) = 2.3 K) is a doublet. The underdamped resonance ((h) over bar Gamma = 0.069 +/- 0.019 meV) Zeeman splits into two modes at E(+/-) = (h) over bar Omega(0) +/- mu(B mu 0)H with alpha = 0.96 +/- 0: 05. A linear extrapolation of the lower peak reaches zero energy at 11.2 +/- 0.5 T, near the critical field for the incommensurate "Q phase." Kenzelmann et al. [Science 321, 1652 (2008)] This, taken with the integrated weight and polarization of the low-energy mode (E(-)), indicates that the Q phase can be interpreted as a Bose condensate of spin excitons. © 2012, American Physical Society.