The phase diagram of CeRh$_{2}$As$_{2}$ for out-of-plane magnetic field
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914021172576256 |
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| author | Khanenko, P. Landaeta, J. F. Ruet, S. Lühmann, T. Semeniuk, K. Pelly, M. Rost, A. W. Chajewski, G. Kaczorowski, D. Geibel, C. Khim, S. Hassinger, E. Brando, M. |
| author_facet | Khanenko, P. Landaeta, J. F. Ruet, S. Lühmann, T. Semeniuk, K. Pelly, M. Rost, A. W. Chajewski, G. Kaczorowski, D. Geibel, C. Khim, S. Hassinger, E. Brando, M. |
| contents | The heavy-fermion superconductor CeRh$_{2}$As$_{2}$ ($T_{\textrm{c}} = 0.35\, \textrm{K}$) shows two superconducting (SC) phases, SC1 and SC2, when a magnetic field is applied parallel to the $c$ axis of the tetragonal unit cell. All experiments to date indicate that the change in SC order parameter detected at $μ_{\textrm{0}}H^{*} \approx 4\, \textrm{T}$ is due to strong Rashba spin-orbit coupling at the Ce sites caused by the locally non-centrosymmetric environments of the otherwise globally centrosymmetric crystalline structure. Another phase (phase I) exists in this material below $T_{\textrm{0}} = 0.54\, \textrm{K}$. In a previous specific heat study [K. Semeniuk et al. Phys. Rev. B, $107$, L220504 (2023)] we have shown that phase I persists up to a field $μ_{\textrm{0}}H_{0} \approx 6\, \textrm{T}$, larger than $H^{*}$. From thermodynamic arguments we expected the phase-I boundary line to cross phase SC2 at a tetracritical point. However, we could not find any signature of the phase-I line inside the SC2 phase and speculated that this was due to the fact that the $T_{0}(H)$ line is almost perpendicular to the $H$ axis and, therefore, invisible to $T$-dependent measurements. This would imply a weak competition between the two order parameters. Here, we report magnetic field dependent measurements of the magnetostriction and ac-susceptibility on high-quality single crystals. We see clear evidence of the singularity at $H_{0}$ inside the SC2 phase and confirm our previous prediction. Furthermore, we observe the transition across the $T^{*}(H)$ line in $T$-dependent specific heat measurements, which show that the $T^{*}(H)$ line is not perpendicular to the field axis, but has a positive slope. Our work supports recent $μ$SR results which suggest coexistence of phase I with superconductivity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_15112 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The phase diagram of CeRh$_{2}$As$_{2}$ for out-of-plane magnetic field Khanenko, P. Landaeta, J. F. Ruet, S. Lühmann, T. Semeniuk, K. Pelly, M. Rost, A. W. Chajewski, G. Kaczorowski, D. Geibel, C. Khim, S. Hassinger, E. Brando, M. Strongly Correlated Electrons Superconductivity The heavy-fermion superconductor CeRh$_{2}$As$_{2}$ ($T_{\textrm{c}} = 0.35\, \textrm{K}$) shows two superconducting (SC) phases, SC1 and SC2, when a magnetic field is applied parallel to the $c$ axis of the tetragonal unit cell. All experiments to date indicate that the change in SC order parameter detected at $μ_{\textrm{0}}H^{*} \approx 4\, \textrm{T}$ is due to strong Rashba spin-orbit coupling at the Ce sites caused by the locally non-centrosymmetric environments of the otherwise globally centrosymmetric crystalline structure. Another phase (phase I) exists in this material below $T_{\textrm{0}} = 0.54\, \textrm{K}$. In a previous specific heat study [K. Semeniuk et al. Phys. Rev. B, $107$, L220504 (2023)] we have shown that phase I persists up to a field $μ_{\textrm{0}}H_{0} \approx 6\, \textrm{T}$, larger than $H^{*}$. From thermodynamic arguments we expected the phase-I boundary line to cross phase SC2 at a tetracritical point. However, we could not find any signature of the phase-I line inside the SC2 phase and speculated that this was due to the fact that the $T_{0}(H)$ line is almost perpendicular to the $H$ axis and, therefore, invisible to $T$-dependent measurements. This would imply a weak competition between the two order parameters. Here, we report magnetic field dependent measurements of the magnetostriction and ac-susceptibility on high-quality single crystals. We see clear evidence of the singularity at $H_{0}$ inside the SC2 phase and confirm our previous prediction. Furthermore, we observe the transition across the $T^{*}(H)$ line in $T$-dependent specific heat measurements, which show that the $T^{*}(H)$ line is not perpendicular to the field axis, but has a positive slope. Our work supports recent $μ$SR results which suggest coexistence of phase I with superconductivity. |
| title | The phase diagram of CeRh$_{2}$As$_{2}$ for out-of-plane magnetic field |
| topic | Strongly Correlated Electrons Superconductivity |
| url | https://arxiv.org/abs/2504.15112 |