Rearrangement of the magnetic excitation spectrum of weakly doped CoCO3 in an external field
Abstract
In crystals of CoCO3 containing a low concentration of the impurities FeCO3, MnCO3, and NiCO3, we have studied the collective rearrangement of the spectrum of the intrinsic and impurity magnetic excitations which takes place as their frequencies approach each other in an external magnetic field. Measurements were performed in the frequency region 1−28 cm−1 in pulsed fields of strengths up to 16 T. The observed anomalies in the spectrum of a weakly doped crystal are explained as a delocalization of the impurity excitations as an indirect interaction arises among them via the excitations of the host crystal matrix. It is shown that the impurity FeCO3 in CoCO3 is an impurity of an orthogonal type, the impurity MnCO3 is of a collinear type, ferromagnetically coupled with the matrix, and NiCO3 is of a collinear type, antiferromagnetically coupled to the CoCO3 matrix.