Abstract

⁵⁷Fe Mössbauer studies of Mn_0.995⁵⁷Fe_0.005P monophosphide have been performed in a wide temperature range including magnetic transitions at the points T_C = 292 K and T_N = 60 K, the former of which (at T_C) is a transition from the paramagnetic to ferromagnetic phase and the latter (at T_N) is a transition with the formation of a helical magnetic structure. The model interpretation of the Mössbauer spectra within the full hyperfine interaction Hamiltonian involves the features of the magnetic structure of undoped MnP phosphide. The analysis of spectra at T < T_N 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 H_hf 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 < T_C (T₀ ≈ 119 K) and that two magnetic structures coexist in the temperature range of T_N < T < T₀. The analysis of the temperature dependence H_hf(T) within the molecular field theory including magnetostriction effects (Bean–Rodbell model) has indicated that the phase transitions at T_N and T_C are of the first and second orders, respectively. It has been established that the magnetic moments μ_Fe undergo strong thermal fluctuations in the wide temperature range of T* < T < T_C (T* ≈ 190 K).

中文翻译：

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57 Fe探针Mössbauer研究MnP磷酸盐中的磁性相变

摘要

^57个的Mn的Fe穆斯堡尔研究_0.995 ⁵⁷的Fe _0.005 P磷化已经在很宽的温度范围内，包括在点磁转变被执行Ť _Ç = 292 K和Ť _Ñ = 60 K，其中前者的（在Ť _Ç）是过渡从顺磁相到铁磁相，铁磁相（在T _N处）是形成螺旋磁性结构的过渡。完全超精细相互作用哈密顿量内的Mössbauer光谱的模型解释涉及未掺杂MnP磷化物的磁性结构特征。T < T处的光谱分析_N已经表明，有必要考虑MnP的螺旋结构的磁晶各向异性和⁵⁷ Fe核上的超精细磁场H _hf的各向异性。已经发现的是，在所述温度范围内的铁磁性相形成的布洛赫型结构域结构Ť ₀ < Ť < Ť _Ç（Ť ₀ ≈119 K），并且在该温度范围的两个磁结构并存Ť _Ñ < Ť < T ₀。温度依赖性H _hf（T）在包括磁致伸缩效应的分子场论中（Bean-Rodbell模型）表明，在T _N和T _C处的相变分别为一阶和二阶。已经确定的是，磁矩μ_的Fe在宽温度范围内的强经受热波动Ť * < Ť < Ť _Ç（Ť *≈190 K）。