Abstract
57Fe Mossbauer studies of Mn0.99557Fe0.005P monophosphide have been performed in a wide temperature range including magnetic transitions at the points TC = 292 K and TN = 60 K, the former of which (at TC) is a transition from the paramagnetic to ferromagnetic phase and the latter (at TN) is a transition with the formation of a helical magnetic structure. The model interpretation of the Mossbauer spectra within the full hyperfine interaction Hamiltonian involves the features of the magnetic structure of undoped MnP phosphide. The analysis of spectra at T < TN has shown that it is necessary to take into account the magnetocrystalline anisotropy of the helical structure of MnP and the anisotropy of the hyperfine magnetic field Hhf on 57Fe nuclei. It has been found that a Bloch-type domain structure is formed in a ferromagnetic phase in the temperature range T0 < T < TC (T0 ≈ 119 K) and that two magnetic structures coexist in the temperature range of TN < T < T0. The analysis of the temperature dependence Hhf(T) within the molecular field theory including magnetostriction effects (Bean–Rodbell model) has indicated that the phase transitions at TN and TC are of the first and second orders, respectively. It has been established that the magnetic moments μFe undergo strong thermal fluctuations in the wide temperature range of T* < T < TC (T* ≈ 190 K).
Published Version
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