SPIN WAVES AND SPIN-PHONON INTERACTIONS.
Abstract
Two pieces of research are described which are both concerned with the interaction of phonons with exchanged-coupled pairs of Ni(2+) ions in the perovskite structure crystal, KMgF3. The phonon-induced transitions between energy states of these pairs were investigated by using a pulse of very high frequency ultrasonics as a probe. The way in which the absorption of the ultrasonics varies with an applied magnetic field enables the investigators, in some cases, to determine what type of pairs are being observed and also the detailed nature of the ultrasonic (i.e. phonon) interaction. A description is also given of the effect for similar specimens of an externally applied magnetic field on the thermal resistance at liquid helium temperatures. The variation of the thermal resistance with the magnetic field cannot be accounted for by phonon interaction with single ions - the effect of pairs of ions must be included. It is then possible to compute the thermal resistance as a function of field and quite good agreement with experiment is achieved. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1968
- Accession Number
- AD0684401
Entities
People
- H. M. Rosenberg
Organizations
- University of Oxford