“…Meanwhile, the smaller the granule size, the easier the granules show superparamagnetic nature, hence superparamagnetic granules show that GMR increases monotonically with decreasing granular size. However, Sang et al [10] found that there is no monotonic relationship between granule size and GMR effect, rather than the existence of a peak value at a certain size for a given temperature; furthermore, Gu et al [11] proved theoretically this phenomenon. Their explanation is that the magnetotransport in a granular system is between those in the CIP (current in the plane) case and CPP (current perpendicular to the plane) case in a multilayer, however, the magnetotransport moves from CPP case to CIP case when the granular size decreases further from the size corresponding to the maximum value of GMR, which is an opposite tendency when granular size is larger than the one corresponding to maximum value of GMR, as a result, GMR decreases rapidly with further decrease in granular size.…”