Abstract: The Griffiths-like phase (GP) is a singular feature related to the formation of random magnetically ordered regions within the paramagnetic phase, at temperatures above that of long-range magnetic ordering. The existence of GP is found in materials with quenched disorder and /or competing magnetic interactions, as in the family of giant magnetocaloric materials R5(SiyGe1-y)4 (R = rare earth). Very recently, our detailed AC-susceptibility measurements on La-diluted system Tb5-xLaxSi2Ge2 revealed that we are able to tune in the formation of short-range ferromagnetic (FM) clusters in the GP in the parent compound Tb5Si2Ge2. The measurements reveal that minute La-substitutions promote a drastic change in the magnetic response of clusters. Here, we would extend the study at the magnetic nanoscale to disclose the size/number of the GP clusters for different levels of La doping and the relation to magnetic disorder. SANS is the ideal probe since it is able to measure magnetic correlations on the relevant length scales. Magnetic field is required to extract the nuclear and magnetic scattering and the field evolution of GP-like clusters.

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