Department of Physics

Quantum electronic matter has long been understood in terms of two limiting behaviors of electrons:  one of delocalized metallic states, and the other of localized magnetic states. Heavy fermions are miniature high-Tc superconductors whose small energy scales provide the possibility of tuning the ground state between these two limits and enable accessing the strange metallic behavior which develops at the brink of localization. I will discuss the attempts [1,2] to map out the phase diagram of heavy-fermions using dynamical large-N method and the Schwinger boson representation of the spins.

I will then highlight the recent observation of quantum critical point and strange metal behavior in the stoichiometric ferromagnetic heavy-fermion CeRh6Ge4 [3]. I will argue that the innocuous easy-plane magnetic anisotropy that is present in this system, produces triplet resonating valence bond (tRVB) states, which lead to a highly entangled ordered phase, similar to a magnetically-frustrated anti-ferromagnet. Doping such a tRVB host provides a route towards realizing triplet superconductivity in a magnetic environment [4].

 

References:

[1] Y. Komijani, P. Coleman, PRL 120, 157206 (2018); ibid 122, 217001 (2019).

[2] J. Wang, Y.-Y. Chang, C.-Y. Mou, S. Kirchner, C.-H. Chung, PRB 102, 115133 (2019).

[3] B. Shen, Y. Zhang, Y. Komijani, M. Nicklas, R. Borth, A. Wang, Y. Chen, Z. Nie, R. Li, X. Lu, H. Lee, M. Smidman,

F. Steglich, P. Coleman, H. Yuan, Nature 579, 51 (2020).

[4] E. König, Y. Komijani, P. Coleman, ArXiv:2109.03851 (2021).