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arXiv · 2210.03673

Electro-nuclear transition into a spatially modulated magnetic state in YbRh$_2$Si$_2$

J. Knapp·L. V. Levitin·J. Nyéki·A. F. Ho·B. Cowan·J. Saunders·M. Brando·C. Geibel·K. Kliemt·C. Krellner
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Abstract

The nature of the antiferromagnetic order in the heavy fermion metal YbRh$_2$Si$_2$, its quantum criticality, and superconductivity, which appears at low mK temperatures, remain open questions. We report measurements of the heat capacity over the wide temperature range 180 $\mu$K - 80 mK, using current sensing noise thermometry. In zero magnetic field we observe a remarkably sharp heat capacity anomaly at 1.5 mK, which we identify as an electro-nuclear transition into a state with spatially modulated electronic magnetic order of maximum amplitude 0.1$\mu_B$. We also report results of measurements in magnetic fields in the range 0 to 70 mT, applied perpendicular to the c-axis, which show eventual suppression of this order. These results demonstrate a coexistence of a large moment antiferromagnet with putative superconductivity.

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J. Knapp, L. V. Levitin, J. Nyéki, A. F. Ho, B. Cowan, J. Saunders, M. Brando, C. Geibel, K. Kliemt, C. Krellner. 2022-10-07. Electro-nuclear transition into a spatially modulated magnetic state in YbRh$_2$Si$_2$. https://doi.org/10.1103/physrevlett.130.126802

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