Bromley D, Wright A J, Jones L A H, Swallow J E N, Beesley T, Batty R, Weatherup R S, Dhanak V R, O'Brien L
Department of Physics, University of Liverpool, Liverpool, L69 7ZE, UK.
Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
Sci Rep. 2022 May 11;12(1):7786. doi: 10.1038/s41598-022-11828-y.
We report on the electronic and magnetic properties of superconductor-ferromagnet heterostructures fabricated by electron beam evaporation on to unheated thermally oxidised Si substrates. Polycrystalline Nb thin films (5 to 50 nm thick) were shown to possess reliably high superconducting critical temperatures ([Formula: see text]), which correlate well with the residual resistivity ratio (RRR) of the film. These properties improved during ex-situ annealing, resulting in [Formula: see text] and [Formula: see text]RRR increases of up 2.2 K ([Formula: see text] 40% of the pre-annealed [Formula: see text]) and 0.8 ([Formula: see text] 60% of the pre-annealed RRR) respectively. Nb/Pt/Co/Pt heterostructures showed substantial perpendicular anisotropy in the ultrathin limit (≤ 2.5 nm), even in the extreme limit of Pt(0.8 nm)/Co(1 nm)/Pt(0.6 nm). These results point to the use of electron beam evaporation as route to line-of-sight deposited, low-thickness, high quality Nb-based superspintronic multilayers.
我们报道了通过电子束蒸发在未加热的热氧化硅衬底上制备的超导 - 铁磁异质结构的电学和磁学性质。多晶铌薄膜（厚度为5至50纳米）显示出具有可靠的高超导临界温度（[公式：见正文]），这与薄膜的剩余电阻率比（RRR）密切相关。这些性质在非原位退火过程中得到改善，导致[公式：见正文]和RRR分别提高了2.2 K（[公式：见正文]为退火前[公式：见正文]的40%）和0.8（[公式：见正文]为退火前RRR的60%）。即使在Pt(0.8纳米)/Co(1纳米)/Pt(0.6纳米)的极限情况下，Nb/Pt/Co/Pt异质结构在超薄极限（≤2.5纳米）下也表现出显著的垂直各向异性。这些结果表明，电子束蒸发可作为一种制备视线沉积、低厚度、高质量铌基超自旋电子多层膜的方法。
