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arXiv · 2206.04704

Quantum-well states at the surface of the heavy-fermion superconductor URu$_2$Si$_2$

Edwin Herrera-Vasco·Isabel Guillamón·Víctor Barrena·William Herrera·Jose Augusto Galvis·Alfredo Levy Yeyati·Jan Rusz·Peter M. Oppeneer·Georg Knebel·Jean Pascal Brison·Jacques Flouquet·Dai Aoki·Hermann Suderow
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Abstract

Electrons can form a two-dimensional electron gas at metal surfaces, where lateral confinement leads to quantum-well states. Such states have been observed for highly itinerant electrons, but it remains an open question whether quantum-well states can be formed from strongly correlated electrons. Here we study atomically flat terraces on surfaces of the heavy-fermion superconductor URu$_2$Si$_2$ using millikelvin scanning tunneling spectroscopy. We observe two-dimensional heavy fermions (2DHF) with an effective mass 17 times the free electron mass that form quantized states separated by a fraction of a meV. Superconductivity at the surface is induced by the bulk into the 2DHF. Our results provide a new route to realize quantum well states in correlated quantum materials.

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Edwin Herrera-Vasco, Isabel Guillamón, Víctor Barrena, William Herrera, Jose Augusto Galvis, Alfredo Levy Yeyati, Jan Rusz, Peter M. Oppeneer, Georg Knebel, Jean Pascal Brison, Jacques Flouquet, Dai Aoki, Hermann Suderow. 2022-06-09. Quantum-well states at the surface of the heavy-fermion superconductor URu$_2$Si$_2$. https://doi.org/10.1038/s41586-023-05830-1

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