Observation of fine domain configuration by detecting micro-Hall effect under scanning probe microscopy

对于FePt/FeCoB(或NiFe)双层薄膜，评估了记录层和软磁衬底之间的磁相互作用的影响。记录层和软磁底层之间的非磁性中间层的存在或不存在在霍尔电压测量中显示了显著不同的结果，表明层间磁相互作用。特别是在FePt/FeCoB体系中，效果更为显着。在FePt层附近存在一层非常薄的FeCoB薄膜，由于它们之间有很强的交换作用，所以在FePt层的磁化过程中有显著的影响。另一方面，由于FePt层的边缘磁通在面内磁化取向上的扰动，FeCoB或NiFe层的软磁性能恶化。发现当FePT层处于交流擦除状态时，软磁性能的恶化程度最大。其原因可以归因于软磁层的边缘场的涨落增加。此外，与FeCoB相比，NiFe薄膜与FePt层共存时更容易受到边缘场的影响。由于霍尔效应是有关材料的固有现象，因此并不总是可能检测到令人满意的结果。在某些情况下，样品成分和物理结构等因素似乎决定了霍尔电压的施加。然而，对于目前所研究的大多数用于高密度磁记录介质或存储器件的材料，自旋相关霍尔效应的应用被认为不仅适合于评估，而且也适合于制造新的器件。基于本研究中发现的结果，霍尔效应的进一步智能应用被寄予厚望。

The effects of magnetic interaction between the recording layer and soft magnetic underlayer were evaluated for an FePt/FeCoB (or NiFe) double-layered thin films. Presence or absence of a non-magnetic intermediate layer between the recording layer and the soft magnetic underlayer revealed significantly different results in the Hall voltage measurement indicating the interlayer magnetic interactions. Especially in the FePt/FeCoB system the effects were remarkable. Existence of a very thin layer of FeCoB thin film adjacent to the FePt layer was found to have significant effect in the magnetization process of the FePt layer due to the strong exchange interaction between them. On the other hand, soft magnetic properties of the FeCoB or the NiFe layer was found to deteriorate due to the disturbance in the in-plane magnetization orientation by the fringing flux from the FePt layer. Deterioration of the soft magnetic properties was found to be in the largest extent when the FePt layer was in AC erased state. The reason can be attributed to the increased fluctuation in the fringing field to the soft magnetic layer. Moreover, compared to the FeCoB,NiFe thin films coexisting with an FePt layer were found more vulnerable to the fringing field. Since the Hall effect is a phenomenon intrinsic to the material in concern, it is not always possible to detect satisfactory results. For some cases factors such as the specimen composition and the physical structure seem to dominate the exertion of the Hall voltage. However, for most of the materials studied so far for the application of high-density magnetic recording media or memory devices, application of spin dependent Hall effects is thought to be suitable not only for evaluation but for the fabrication of new devices also. Based on the results found in this study further intelligent applications of the Hall effects are highly expected.