Quantum confinement of electronic states in a bulk heavy fermion crystal

Electronic states become quantized when confined in a potential well. This well-known phenomenon is observed for example in quantum dots or thin films [1]. In these cases, the confinement is created artificially by the microscopic dimensions of the system. Surprisingly, we recently observed the presence of confined electronic states in a bulk crystal of CeCoIn₅, a prototypical heavy fermion superconductor [2]. Our recent ARPES results revealed multiple electronic bands that were not observed previously [3-5] and are not predicted by theory [6]. Interestingly, the energy position of these bands follows the simple relation expected for a quantum well. In comparison to thin films, the origin of the confinement potential creating these quantized states in CeCoIn₅ is still unclear and requires more investigations.

[1] T.C. Chiang, Surf. Sci. Rep. 39, 181 (2000).
[2] C. Petrovic, et al., J. Phys. Condens. Matter 13, L337 (2001).
[3] A. Koitzsch, et al., PRB 88, 035124 (2013).
[4] Q. Y. Chen, et al., PRB 96, 045107 (2017).
[5] S. Jang, et al., arXiv:1704.08247
[6] S. Elgazzar, et al., PRB 69, 214510 (2004).