Physical property of two components nono-crystals prepared with GDM

在本研究项目中，研究了由多元素组成的纳米晶体。对气体冷凝沉淀法(GDM)进行了两种不同的工艺改进，以实现双组分纳米晶体的制备。此外，还报道了简单GDM法制备的单元素纳米晶的基本性质。作为多元纳米晶体系的基础，GDM镍纳米晶体的磁性得到了研究。沉积时薄膜由直径约为9 nm的细小颗粒组成。400℃以下的热退火使晶粒尺寸增大到20 nm左右。纳米晶的矫顽力与颗粒尺寸小于13 nm的-6次方成正比。这可以用随机各向异性模型来解释。得到的有效局域磁各向异性为1.9-3.5×104J/m~3，是块体Ni的2-5倍。从场冷磁化强度的测量来看，没有观察到交换各向异性引起的Hc漂移。The…氧化产生的颗粒周围较多的反铁磁层似乎不是导致各向异性的原因。通过混合来自两个不同来源的超细颗粒流，制备了包括铁和钴等铁磁性金属在内的两组分纳米晶体。在细颗粒混合在衬底上的情况下，组成被大规模调制，这意味着流动不能以这种方式很好地混合。下一步，我们混合了传输管中的流动，调制得到了改善，然而，在混合光束的每一道中都发现了明显的元素分离。另一种改性GDM的技术，即将细颗粒与基片上的其他溅射金属混合，已被测试以实现颗粒状材料。与以往的混合方式相比，混合效果有了明显的改善。对于Co-Ag系统，GMR是预期的，但只发现了很小的磁阻。这可能归因于Co颗粒的大小，并计划进行进一步的研究。较少

In this research project, nano-crystals composed of multi-elements were investigated. 2 different techniques, which are modified from Gas condensation and Deposition Method (GDM), were tested to realize 2 components nano-crystals. Additionally, basic properties of single element nanocrystals produced by the simple GDM are also reported.As basics of the multi-element nano-crystal system, magnetism of GDM Ni nano-crystals was investigated. As deposited films were composed of fine particles with approximately 9 nm in diameter. Thermal annealing up to 400°C increased the grain size of around 20 nm. Coercive forces of the nano-crystals vary in accordance with the - 6 powers of grain size smaller than 13nm. This is explained by the Random Anisotropy Model. Effective local magnetic anisotropy is deduced to be 1.9-3.5 x 104 J/ m3 and this magnitude is 2-5 times larger than that of bulk Ni. From the field cool magnetization measurement, Hc shift due to exchange anisotropy was not observed. The … More antiferromagnetic layer around grains originated from oxidation seems not to be responsible for the anisotropy.Two components nano-crystals including ferromagnetic metals such as Fe and Co were fabricated by mixing ultrafine particle flows from two individual sources. In the case where fine particles were mixed on a substrate, the composition was modulated in a large scale and this means flows do not mix well in this way. Next, we mixed the flows in the transfer tube and the modulation was improved, however, clear separation of the elements was found in an each trace of a mixed beam. Another technique modifying GDM, where fine particles were mixed with other sputtered metals on the substrate, has been tested to realize granular materials. By this way the mixing was remarkably improved compared with former ways. GMR was expected in a case of Co-Ag system, however only small magneto-resistance was found. This may be attributed to the size of Co particles and further investigation is planned. Less