Magnetic interactions in heavy-fermion metals arise from the two opposing limits of localized and itinerant electrons. This duality is responsible for numerous novel quantum-matter states, such as unconventional superconductivity, electronic nematicity, or skyrmion-lattice order in centrosymmetric crystals. The Kondo-lattice model, which captures the underlying physics of f-electrons, is notoriously difficult to solve for real materials and was therefore never solved quantitatively. CeIn3 is a prototypical example having a relatively simple crystal structure and showing quantum critical behavior as well as unconventional superconductivity on pressure tuning. At ambient conditions and temperatures below 10 K, CeIn3 establishes antiferromagnetic long-range order. In the study that I will present, we show that a multi-orbital periodic Anderson model together with ab-initio bandstructure calculations can be reduced to a modified Kondo-Heisenberg model that captures all relevant magnetic interactions and that further establishes the antiferromagnetic ground state. Notably, as a key signature the model suggests the emergence of magnons that have extremely high velocities. We used high-resolution neutron spectroscopy to probe the low-energetic magnetic excitations and found astounding agreement with the theoretical prediction. The same soft modes may be the key for the emergence of superconductivity and may further guide us to a better understanding not only of unconventional superconductivity, but also of exotic quantum states across all classes of strongly correlated electron materials.
See also Ref. 
 W. Simeth, Z. Wang, E. A. Ghioldi, D. M. Fobes, A. Podlesnyak, N. H. Sung, E. D. Bauer, J. Lass, J. Vonka, D. G. Mazzone, C. Niedermayer, Y. Nomura, R. Arita, C. D. Batista, F. Ronning, and M. Janoschek, arXiv:2208.02211.
Dr. Jitae Park
Dr. Theresia Heiden-Hecht
Dr. Apostolos Vagias