Dresden 2026 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 62: Correlated Electrons – Poster II

TT 62.6: Poster

Mittwoch, 11. März 2026, 15:00–17:00, P4

Exploring the reciprocal space of CeRh₂As₂ at a high brilliance SwissFEL beamline — •Alexander Mistonov¹, Jakub Vonka², Alexander Steppke², Swarnamayee Mishra¹, Maël Clémence², Adrian Rutschmann², Karina Kazarian², Wenxiang Hu², Bill Pedrini², Simon Gerber², Elena Hassinger³, Seunghyun Khim⁴, and Jochen Geck¹ — ¹TU Dresden, Dresden, Germany — ²PSI, Villigen, Switzerland — ³KIT, Karlsruhe, Germany — ⁴MPI CPfS, Dresden, Germany

CeRh₂As₂ hosts two superconducting (SC) phases tuned by magnetic field [1] and undergoes an additional transition at T₀ = 0.55 K (with T_c = 0.35 K) [2]. The nearly non-magnetic and strongly anisotropic nature of the T₀ phase suggests an itinerant quadrupolar order of the Ce moments [3]. Since Ce-4f electrons couple to the lattice, a lowering of the tetragonal symmetry at T₀ is anticipated.

To test this, we performed single-crystal X-ray diffraction in non-resonant mode and at the Ce L₃ edge to search for symmetry reduction and signatures of multipolar order. We examined a possible splitting of the high-q (552) Bragg reflections and conducted energy-dependent rocking-curve scans near the (π, π, 0) point.

These subtle effects were probed at ultralow temperatures using a high-brilliance SwissFEL beamline combined with a dilution refrigerator. The results are presented in this work.
[1] S. Khim et al., Science 373, 1012 (2021).
[2] K. Semeniuk et al., Phys. Rev. B 107, L220504 (2023).
[3] D. Hafner et al., Phys. Rev. X 12, 011023 (2022).

Keywords: CeRh2As2