The effects of magnetic field on the spin wave spectra, magnon density of states, and the magnon contribution to the specific heat have been calculated for the antiferromagnet NiF,. The results show that the Davydov splitting of the k = 0 magnons decreases with increming field whilst the zone boundary magnons remain degenerate. The spin wave contribution to the specific heat decreases with increasing field as expected.Die Einfliisse eines magnetischen Feldes a d die Spinwellenspektren, Magnon-Zustandsdichten und auf den Magnonen-Beitrag zur spezifischen Wiirme wurden fiir antiferromagnetisches NiF, berechnet. Die Ergebnisse zeigen, dal) die Davydov-Aufspaltung der k = 0 Magnonen mit steigendem Feld abnimmt, wiihrend die Zonengrenzen-Magnonen entartet bleiben. Wie erwartet, nimmt der Beitrag der Spinwellen zur spezifischen Wiirme mit steigendem Feld ab.

No abstract

By application of a modified Burnside method, based on the explicit determination of class multiplication coefficients h~jk, the character table of the hypercubic point group in six dimensions B 6 -a group of order 46 080 -is obtained. This point group is used in the study of quasicrystals through a projection from six to three dimensions.