Visualization of simultaneous hybridization and magnetic exchange in the semimetal CeSb*

Understanding the many-body physics that leads to coexisting quantum ground states is at the center of some of the deepest problems in condensed matter physics, from high-temperature superconductivity to quantum magnetism. The so-called heavy fermion compounds are an archetype of such correlated phenomena, manifesting signatures of both magnetically ordered and many-body entangled states. The compound CeSb, as a semimetal, is an unusual example where such states not only coexist but are coincident, and understanding the mechanism behinds this has eluded a complete theory for decades. Using on-resonance angle-resolved photoemission spectroscopy, we are able to highlight Ce f-bands and provide a direct visualization of how they interact with delocalized electrons and holes in the system. We find there are two distinct modes of interaction, whose action is allowed to occur simultaneously due to their separation in momentum space. This study illustrates a simple but rare example of material how the quantum mechanical independence of momentum space allows distinct many-body phenomena to coexist.