**4. Conclusions**

In conclusion, this proposed method provides a good instrument for the characterization of electronic interactions or correlations in the material, although the absolute values of *SE* or Δ*SE* obtained may, in some cases, need to be corrected (further discussed in [1]). In the case of magnetocaloric materials, the e ffect of the magnetic field on the electronic entropy change can be traced. In the case of alloys, the e ffect of the atomic disorder can also be traced on the free electrons. In order to gain deeper insight on the physics of disordered systems or systems with concurring interactions, the goal of future research might be to develop the statistical methods under the point of view of thermodynamics that would allow us to describe the statistical collectivity of electrons. In this way, we could transform the qualitative results of our experiments into quantitative predictions.

**Author Contributions:** Conceptualization: N.P. and G.S.; methodology: C.W., B.W., M.K., A.K., J.F., and N.P.; resources and supervision: K.N.; writing—original draft preparation, N.P., C.W., G.S.; writing—review and editing, N.P., C.W., G.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This project (Grant No. 100245375) is funded by the European Regional Development Fund (ERDF) and the Free State of Saxony.

**Acknowledgments:** The authors want to thank D. Seifert and R. Uhlemann in IFW Dresden for technical support. Further, G.S. and N.P. want to thank Anja Waske and Sebastian Fähler in IFW Dresden for fruitful discussions. M.K. and B.W. greatfully acknowledge financial support from the Germany Federal Ministry for Economic Affairs and Energy under Project Number 03ET1374B.

**Conflicts of Interest:** The authors declare no conflict of interest.
