Possible scenarios for the origin of multiple superconducting phases in CeRh₂As₂

The recently discovered superconductor CeRh₂As₂ has attracted much attention due to the presence of a field-induced, even-odd parity transition within the superconducting (SC) state at μ₀H* ≈ 4 T applied along the tetragonal c axis [1,2]. Further, a new state precursing the SC state occurs below T₀ ~ 0.4 K and was suggested to be a quadrupole-density-wave (QDW) state [3].

In this talk, I will present our recent anisotropic magnetotransport measurements [4], performed on a focused ion-beam fabricated microstructured device, investigating the suggested QDW state. For a magnetic field applied along the tetragonal a axis, T₀ is enhanced with magnetic field reaching ∼1.75 K at 16 T. On the other hand, for a magnetic field applied along the c axis, T₀ is suppressed below our base temperature ∼0.35 K by μ₀H ∼ 4.5 T, a field close to the previously reported field-induced transition within the SC state. Based on our observations, we propose two scenarios on how the suppression of the proposed QDW state leads to multiple SC phases in CeRh₂As₂. Our work opens a new discussion about how intertwined quantum phases might lead to multiphase superconductivity.

References:

1. S. Khim, et al., Science 373, 1012 (2021).

2. J. F. Landaeta, et al., Phys. Rev. X 12, 031001 (2022).

3. D. Hafner, et al., Phys. Rev. X 12, 011023 (2022).

4. S. Mishra., et al., Phys. Rev. B 106, L140502 (2022)