Ranecka Agnieszka, Pugaczowa-Michalska Maria, Smardz Lesław
Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland.
Materials (Basel). 2025 Feb 5;18(3):697. doi: 10.3390/ma18030697.
V/Fe multilayers were prepared on naturally oxidized Si(100) substrates at room temperature (RT) by UHV magnetron sputtering. Mixing effects at the Fe-V interfaces were investigated in-situ, directly after deposition, by means of X-ray photoelectron spectroscopy (XPS). The results of systematic in-situ XPS studies of the integral intensity of the Fe-2p peak, as a function of the nominal thickness of the Fe sublayer deposited on vanadium, allowed us to estimate the thickness of the pure iron layer that forms the mixed layer at about 0.4 nm. Assuming the same thickness of the vanadium layer that forms the mixed layer, the estimated thickness of the mixed layer near the Fe-V interface was about 0.8 nm. In the analysis of magnetic hysteresis loops, in addition to the bilinear (J) and biquadratic (J) coupling constant, the contribution of the cubic exchange constant (J) was taken into account, which also contributed significantly to the total energy. Higher order interactions (J and J) are particularly important for V spacer thicknesses greater than 7 atomic monolayers. Hydrogen absorption in V/Fe multilayers at RT and a pressure of about 1 bar causes an increase in the biquadratic coupling constant J, while the values of J and J are reduced. A comparison of the obtained experimental results and available theoretical models leads to the conclusion that the mechanism of "fluctuating thickness of the non-magnetic spacer" could be responsible for the biquadratic exchange coupling. On the other hand, the "loose spins" model can explain the cubic coupling in the V/Fe multilayers. The modification of the interlayer exchange coupling using hydrogen is fully reversible.
通过超高真空磁控溅射在室温（RT）下于自然氧化的Si(100)衬底上制备了V/Fe多层膜。在沉积后直接通过X射线光电子能谱（XPS）对Fe-V界面处的混合效应进行了原位研究。对Fe-2p峰的积分强度进行系统的原位XPS研究结果表明，该强度是沉积在钒上的Fe子层标称厚度的函数，这使我们能够估计形成混合层的纯铁层厚度约为0.4nm。假设形成混合层的钒层厚度相同，则Fe-V界面附近混合层的估计厚度约为0.8nm。在磁滞回线分析中，除了双线性（J）和双二次（J）耦合常数外，还考虑了立方交换常数（J）的贡献，其对总能量也有显著贡献。对于V间隔层厚度大于7个原子单层的情况，高阶相互作用（J和J）尤为重要。在室温和约1巴的压力下，V/Fe多层膜中的氢吸收会导致双二次耦合常数J增加，而J和J的值会降低。将获得的实验结果与现有的理论模型进行比较得出结论，“非磁性间隔层厚度波动”机制可能是双二次交换耦合的原因。另一方面，“松散自旋”模型可以解释V/Fe多层膜中的立方耦合。利用氢对层间交换耦合的改性是完全可逆的。
