ESR SPECTRA OF DONOR CLUSTERS

Two problems are considered: The one is the calculation of the ESR spectrum due to a donor pair in the case of the exchange interaction J being comparable to the hyperfine constant A. The other is the calculation of the ESR spectrum due to three interacting donors. For a donor pair, the calculated spectrum is averaged over the random distribution of donors. In both cases it is shown that a broad background appears, which extends outside the two hyperfine lines situated at g μBH±A/2. For a donor pair, the background is asymmetric about the central line. For three interacting donors, the background is symmetric when all the exchange interactions among them are far larger than A, while a preliminary calculation indicates that the background becomes asymmetric when some of the exchange interactions are comparable to A. Such an asymmetric background as calculated in the present paper might be a partial origin of the observed one. © 1968, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.