CeRhIn5 is a Kondo-lattice prototype in which a magnetic field B∗≃ 30 T induces an abrupt Fermi-surface (FS) reconstruction and pronounced in-plane electrical transport anisotropy all within its antiferromagnetic state. Though the antiferromagnetic order at zero field is well-understood, the origin of an emergent state at B∗ remains unknown due to challenges inherent to probing states microscopically at high fields. Here, we report low-temperature Nuclear Magnetic Resonance (NMR) measurements revealing a discontinuous decrease in the 115In formal Knight shift, without changes in crystal or magnetic structures, of CeRhIn5 at fields spanning B∗. We show that the emergent state above B∗ results from a change in Ce's 4f orbitals that arises from field-induced evolution of crystal-electric field (CEF) energy levels. This change in orbital character enhances hybridisation between the 4f and the conduction electrons (c.e.) that leads ultimately to an itinerant quantum-critical point at Bc0≃ 50 T.
@article{arxiv.1905.02861,
title = {Orbitally defined field-induced electronic state in a Kondo lattice},
author = {G. G. Lesseux and H. Sakai and T. Hattori and Y. Tokunaga and S. Kambe and P. L. Kuhns and A. P. Reyes and J. D. Thompson and P. G. Pagliuso and R. R. Urbano},
journal= {arXiv preprint arXiv:1905.02861},
year = {2020}
}