Resolving multipolar ordering, superconductivity and Rashba effect in the newly discovered quantum critical system CeRh2As2

Kondo lattice systems are intermetallic compounds based on the rare-earth elements Cerium or Ytterbium, which present very unusual properties at low temperatures. Their ground state can be continuously tuned from an ordered to a disordered state through a so-called quantum critical point, e.g. by chemical substitution or external parameters such as pressure. In the vicinity of these quantum-critical points, the resulting very strong electronic correlation effects lead to very peculiar phenomena such as, for instance, unconventional superconductivity or charge carriers with extremely large effective masses thousand times larger than that of a free electron. Often, unconventional magnetic or multipolar ordered states, which are far from being understood, can also be observed.

We recently discovered a new Kondo lattice system, CeRh2As2, which in its pure state already is very close to a quantum critical point. Intriguingly, the properties which could be observed so far indicate a new, unprecedented situation based on interactions between dipolar magnetic order, multipolar order, superconductivity and a large Rashba effect.

The purpose of this project is to clarify the origin of the peculiar properties of this new system by tuning it by chemical substitution. We are looking for a PhD student with background in material science and solid state physics, who is equally interested in the synthesis and crystal growth of exotic materials as well as in the study of their magnetic, thermodynamic and electronic properties at very low temperatures down to the mK regime. We expect about half of the work to be devoted to the crystal growth of pure and partially substituted CeRh2As2, and the other half to the experimental investigation of its properties.


S. Khim, J. F. Landaeta, J. Banda, N. Bannor, M. Brando, P. M. R. Brydon, D. Hafner, R. Küchler, R. Cardoso-Gil, U. Stockert, A. P. Mackenzie, D. F. Agterberg, C. Geibel, E. Hassinger
Field-induced transition from even to odd parity superconductivity in CeRh2As2
Science 373, 1012–1016 (2021)
M. Kibune, S. Kitagawa, K. Kinjo, S. Ogata, M. Manago, T. Taniguchi, K. Ishida, M. Brando, E. Hassinger, H. Rosner, C. Geibel, and S. Khim
Observation of Antiferromagnetic Order as Odd-Parity Multipoles inside the Superconducting Phase in CeRh2As2
Phys. Rev. Lett. 128, 057002 (2022)
D. Hafner, P. Khanenko, E.-O. Eljaouhari, R. Küchler, J. Banda, N. Bannor, T. Lühmann, J. F. Landaeta, S. Mishra, I. Sheikin, E. Hassinger, S. Khim, C. Geibel, G. Zwicknagl, and M. Brando
Possible Quadrupole Density Wave in the Superconducting Kondo Lattice CeRh2As2
Phys. Rev. X 12, 011023 (2022)
S. Kitagawa, M. Kibune, K. Kinjo, M. Manago, T. Taniguchi, K. Ishida, M. Brando, E. Hassinger, C. Geibel, and S. Khim
Two-Dimensional XY-Type Magnetic Properties of Locally Noncentrosymmetric Superconductor CeRh2As2
J. Phys. Soc. Jpn. 91, 043702 (2022)

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