Papers by Keyword: Localized Magnetic Moments

Abstract: The temperature dependences of the magnetic susceptibility χ (T) of diluted magnetic semiconductor HgSe:Ni (1·10¹⁸ < N_Ni < 1·10¹⁹) cm^-3 were investigated. It was found that paramagnetic part of the susceptibility which is wholly due to the effect of the impurities in the range of temperature from 1.8 to 200 K is described by the Curie-Weiss law. The analysis of the concentration dependence of the Curie constant C(N_Ni) based on the model of the hybridized electronic states was carried out. The application of this model allowed us to determine the microscopic parameters of the electronic structure of these crystals (the effective spin of the hybridized electronic states at the nickel impurity S_i and the resonance concentration of donor electrons n_0d).

Abstract: Perturbed gamma-gamma angular correlation (PAC) spectroscopy is a precise and highly efficient tool to follow the temperature dependence of local magnetic fields in any material. Its resolution and efficiency does not depend on temperature and therefore can measure local fields at low as well as high temperature with the same accuracy. Due its versatility in using different probe nuclei it can sense the local magnetic fields at different sites in the crystalline structure of materials. In this review, important results obtained with PAC spectroscopy are shown in two classes of materials: transition metal and transition-metal based compounds and rare earth elements and rare-earth-element based compounds using mainly three different probe nuclei: ¹¹¹Cd, ¹⁸¹Ta and ¹⁴⁰Ce. PAC spectroscopy has contributed to the systematic study of the magnetic hyperfine field in impurities in matrices of Fe, Co and Ni as well as in transition-metal based Heusler alloys. It has also provided important contribution to the investigation of magnetism in rare-earth elements and intermetallic compounds. An still open issue concerning the local fields in metallic magnetic compounds and elements is the exchange interaction between the magnetic ions of the host and a dilute magnetic impurity, which acts as a defect in the magnetic lattice. PAC spectroscopy has been contributing to study this problem with success. Also shown in this review is the crucial role of ab-initio first principle calculations in the interpretation of PAC results.