Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 7: Postersession Matter at Low Temperature: Materials

TT 7.2: Poster

Monday, March 23, 2009, 13:00–16:45, P1B

Interacting nuclear dipoles of particles involved in atomic tunnelling processes influence the amplitude of polarisation echoes in glassy glycerol — •Gudrun Fickenscher, Masoomeh Bazrafshan, Kathrin Reinhold, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Universität Heidelberg, Germany

In recent years, an unexpected magnetic field effect of the dielectric properties of non-magnetic glasses was discovered, that cannot be described by the otherwise widely accepted standard tunnelling model. It has since been proven, that it is caused by nuclear electric quadrupole moments of the tunnelling entities interacting with local electric field gradients which change their direction as the particle tunnels from one well to the other. Due to its anisotropic nature the interaction of nuclear magnetic dipole moments leads to an analogous effect on a smaller energy scale. We have studied this effect by measuring the dielectric 2-pulse polarisation echo amplitude of various partially deuterated glycerol samples as a function of the delay time and the magnetic field. Numerical calculations were performed assuming particular tunnelling motions as well as different numbers of dipole moments on the tunnelling entity and in its surrounding. With reasonable parameters these calculations fit the data satisfactorily both qualitatively and quantitatively, giving deeper insight into the motion of tunnelling systems in glassy glycerol.