Spin-wave excitations in presence of nanoclusters of magnetic impurities
Spin-wave excitations in presence of nanoclusters of magnetic impurities
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DOI：
10.1088/1367-2630/16/3/033004
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发表时间：
2013-01
影响因子：
3.3
通讯作者：
A. Chakraborty;Paul Thomas Wenk;S. Kettemann;R. Bouzerar;G. Bouzerar
中科院分区：
文献类型：
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作者：
A. Chakraborty;Paul Thomas Wenk;S. Kettemann;R. Bouzerar;G. Bouzerar
在无序/稀释体系中，纳米尺度的非均质性和杂质聚集性会极大地影响磁性和输运性质，从而产生丰富而复杂的现象。然而，这些系统的物理学仍然需要更详细地探索，这可以从稀缺的文献中看到。我们从理论上详细分析了纳米尺度的不均匀性对稀释磁系统中自旋激发谱的影响。计算是在相对较大的系统上执行的(最高N = 66.3 ？>)。研究发现，即使是低浓度的非均匀性也会对磁振子态密度和磁振子激发产生剧烈的影响。在杂质之间的短程磁相互作用的情况下，这些影响变得更加明显。与临界温度T C ？>，在先前的研究中报道，自旋刚度D在纳米尺度不均匀性的存在下被系统地抑制。此外，发现D强烈依赖于不均匀性的浓度，簇大小以及磁相互作用的范围。研究结果对自旋电子学的潜在应用前景进行了讨论。我们相信，这项详细的数值工作可以开启未来的实验研究，用最合适的工具——非弹性中子散射来探测这一丰富的物理现象。
Nanoscale inhomogeneities and impurity clustering are often found to drastically affect the magnetic and transport properties in disordered/diluted systems, giving rise to rich and complex phenomena. However, the physics of these systems still remains to be explored in more detail as can be seen from the scarce literature available. We present a detailed theoretical analysis of the effects of nanoscale inhomogeneities on the spin excitation spectrum in diluted magnetic systems. The calculations are performed on relatively large systems (up to N = 66 3 ?> ). It is found that even low concentrations of inhomogeneities have drastic effects on both the magnon density of states and magnon excitations. These effects become even more pronounced in the case of short-ranged magnetic interactions between the impurities. In contrast to the increase of critical temperatures T C ?> , reported in previous studies, the spin-stiffness D is systematically suppressed in the presence of nanoscale inhomogeneities. Moreover D is found to strongly depend on the inhomogeneities’ concentration, the cluster size, as well as the range of the magnetic interactions. The findings are discussed in the prospect of potential spintronics applications. We believe that this detailed numerical work could initiate future experimental studies to probe this rich physics with the most appropriate tool, inelastic neutron scattering.