Deviation from Curie-Weiss law in magnetic susceptibility

[kratochvilova]

Hi, I have some problems with interpretation of my dates of magnetic susceptibility measured on heavy compound Ce₂RhIn₈ doped by Pd on Rh site. The curves measured along c-direction follow the Curie-Weiss law only in the high temperature region (~200-300 K) and then deviate from it. The curves are strongly convex. I know that the opposite case, a concave curve, can be explained by intermediate valence, but I am not sure how to explain this behavior - by CEF, Kondo...? Just to be accurate, the reciprocal susceptibility along a-direction follows CW law to ~15 K.

 

[BigJDubs]

It is difficult to say without more data, but it is possible that the deviation from the Curie-Weiss law at high temperature could be due to Kondo effect or CEF (crystal field) effects. The former occurs when a localized magnetic moment interacts with delocalized conduction electrons and results in an increase in the susceptibility. The latter occurs when the crystal environment of the ions causes the splitting of otherwise degenerate energy levels, leading to a decrease in the susceptibility. A concave curve generally indicates a presence of intermediate valence, where the electrons can occupy different energy levels due to hybridization with other orbitals. It can also be caused by nonlinear spin-orbit coupling effects or multiple exchange interactions. In any case, it is likely that the behavior of the reciprocal susceptibility along the c-direction could be explained by a combination of several effects, which could include Kondo effect, CEF, intermediate valence, and so on. It is worth taking a closer look at the available data to see if you can identify the underlying mechanisms at play.