Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, People's Republic of China.
J Phys Condens Matter. 2013 Apr 3;25(13):135703. doi: 10.1088/0953-8984/25/13/135703. Epub 2013 Mar 11.
Ba(Fe(1-x)Mn(x))2As2 compounds with x = 0.016 and 0.064 have been studied by (57)Fe Mössbauer spectroscopy in the temperature range from 30 to 300 K. The unusual magnetic splitting spectra at lower temperatures have been analyzed using the distribution of hyperfine field. It is found that the influence of Mn dopant spreads beyond the nearest Fe magnetic moments, and the Fe 3d electrons behave more localized compared with those in the electron-doped compounds. This reduces the hyperfine interactions between iron nucleus and the sounding electrons. The shape of the spin density wave is near-rectangular at 6.4%-Mn doping, indicating quite different interband interactions compared with electron-doped compounds. A distinct broadening of the spectral linewidth around the spin density wave transition temperature has been observed and the spin correlation time is deduced according to the linewidth. The correlation time is further related to the spin-lattice relaxation rate by a simple model and the magnetic fluctuations can be explored effectively. It is found that the magnetic fluctuations of iron spins in Mn-doped compounds can be described well using a phenomenological two-component model and the resulting Curie-Weiss temperature is far from the quantum critical point at the present doping levels.
对 Ba(Fe(1-x)Mn(x))2As2 化合物（x = 0.016 和 0.064）进行了（57）Fe Mössbauer 光谱学研究，温度范围为 30 至 300 K。在较低温度下，异常的磁分裂谱使用超精细场分布进行了分析。结果发现，Mn 掺杂的影响超出了最近的 Fe 磁矩的范围，与电子掺杂化合物相比，Fe 3d 电子表现出更局域的性质。这降低了铁原子核与发声电子之间的超精细相互作用。在 6.4%-Mn 掺杂时，自旋密度波的形状接近矩形，表明与电子掺杂化合物相比，能带间相互作用明显不同。在自旋密度波转变温度附近观察到谱线宽度明显变宽，并根据线宽推导出自旋关联时间。根据简单模型，关联时间与自旋晶格弛豫率进一步相关，可以有效地探索磁涨落。结果发现，Mn 掺杂化合物中铁自旋的磁涨落可以用唯象的两分量模型很好地描述，并且得到的居里-外斯温度远未达到目前掺杂水平下的量子临界点。
