Elastic response of [111]-tunneling impurities

Details Elastic response of [111]-tunneling impurities Elastic response of [111]-tunneling impurities

2000-09-21

arxiv.org/abs/cond-mat/0009325v1

Physics

Condensed Matter

19 pages, 5 figures, submitted to JoP Condens Matter

Scientific paper

10.1088/0953-8984/13/7/310

We study the dynamic response of a [111] quantum impurity, such as lithium or cyanide in alkali halides, with respect to an external field coupling to the elastic quadrupole moment. Because of the particular level structure of a eight-state system on a cubic site, the elastic response function shows a biexponential relaxation feature and a van Vleck type contribution with a resonance frequency that is twice the tunnel frequency $\Delta/\hbar$. This basically differs from the dielectric response that does not show relaxation. Moreover, we show that the elastic response of a [111] impurity cannot be reduced to that of a two-level system. In the experimental part, we report on recent sound velocity and internal friction measurements on KCl doped with cyanide at various concentrations. At low doping (45 ppm) we find the dynamics of a single [111] impurity, whereas at higher concentrations (4700 ppm) the elastic response rather indicates strongly correlated defects. Our theoretical model provides a good description of the temperature dependence of $\delta v/v$ and $Q^{-1}$ at low doping, in particular the relaxation peaks, the absolute values of the amplitude, and the resonant contributions. From our fits we obtain the value of the elastic deformation potential $\gamma_t=0.192$ eV.

Affiliated with

Also associated with

No associations

Rating

Elastic response of [111]-tunneling impurities does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Elastic response of [111]-tunneling impurities, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elastic response of [111]-tunneling impurities will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-131263