Salikhov R, Reichel L, Zingsem B, Abrudan R, Edström A, Thonig D, Rusz J, Eriksson O, Schultz L, Fähler S, Farle M, Wiedwald U
Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany.
J Phys Condens Matter. 2017 Jul 12;29(27):275802. doi: 10.1088/1361-648X/aa7498. Epub 2017 May 22.
Tetragonally strained interstitial Fe-Co-B alloys were synthesized as epitaxial films grown on a 20 nm thick AuCu buffer layer. Different ratios of the perpendicular to in-plane lattice constant c/a = 1.013, 1.034 and 1.02 were stabilized by adding interstitial boron with different concentrations 0, 4, and 10 at.%, respectively. Using ferromagnetic resonance (FMR) and x-ray magnetic circular dichroism (XMCD) we found that the total orbital magnetic moment significantly increases with increasing c/a ratio, indicating that reduced crystal symmetry and interstitial B leads to a noticeable enhancement of the effect of spin-orbit coupling (SOC) in the Fe-Co-B alloys. First-principles calculations reveal that the increase in orbital magnetic moment mainly originates from B impurities in octahedral position and the reduced symmetry around B atoms. These findings offer the possibility to enhance SOC phenomena-namely the magnetocrystalline anisotropy and the orbital moment-by stabilizing anisotropic strain by doping 4 at.% B. Results on the influence of B doping on the Fe-Co film microstructure, their coercive field and magnetic relaxation are also presented.
四方应变的间隙铁钴硼合金被合成为生长在20纳米厚的金铜缓冲层上的外延薄膜。通过分别添加浓度为0、4和10原子百分比的间隙硼，稳定了不同的垂直与面内晶格常数比c/a = 1.013、1.034和1.02。利用铁磁共振（FMR）和X射线磁圆二色性（XMCD），我们发现总轨道磁矩随着c/a比的增加而显著增加，这表明晶体对称性的降低和间隙硼导致铁钴硼合金中自旋轨道耦合（SOC）效应的显著增强。第一性原理计算表明，轨道磁矩的增加主要源于八面体位置的硼杂质以及硼原子周围对称性的降低。这些发现提供了通过掺杂4原子百分比的硼来稳定各向异性应变，从而增强SOC现象（即磁晶各向异性和轨道磁矩）的可能性。还展示了硼掺杂对铁钴薄膜微观结构、矫顽场和磁弛豫影响的结果。
