| Autor: |
Smidman, M., Stockert, O., Arndt, J., Pang, G. M., Jiao, L., Yuan, H. Q., Vieyra, H. A., Kitagawa, S., Ishida, K., Fujiwara, K., Kobayashi, T. C., Schuberth, E., Tippmann, M., Steinke, L., Lausberg, S., Steppke, A., Brando, M., Pfau, H., Stockert, U., Sun, P. |
| Předmět: |
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| Zdroj: |
Philosophical Magazine; Nov2018, Vol. 98 Issue 32, p2930-2963, 34p |
| Abstrakt: |
In this paper the low-temperature properties of two isostructural canonical heavy-fermion compounds are contrasted with regards to the interplay between antiferromagnetic (AF) quantum criticality and superconductivity. For CeCu2Si2, fully-gapped d-wave superconductivity forms in the vicinity of an itinerant three-dimensional heavy-fermion spin-density-wave (SDW) quantum critical point (QCP). Inelastic neutron scattering results highlight that both quantum critical SDW fluctuations as well as Mott-type fluctuations of local magnetic moments contribute to the formation of Cooper pairs in CeCu2Si2. In YbRh2Si2, superconductivity appears to be suppressed at T ⪆ 10 mK by AF order (TN = 70 mK). Ultra-low temperature measurements reveal a hybrid order between nuclear and 4f-electronic spins, which is dominated by the Yb-derived nuclear spins, to develop at TA slightly above 2 mK. The hybrid order turns out to strongly compete with the primary 4f-electronic order and to push the material towards its QCP. Apparently, this paves the way for heavy-fermion superconductivity to form at Tc = 2 mK. Like the pressure - induced QCP in CeRhIn5, the magnetic field - induced one in YbRh2Si2 is of the local Kondo-destroying variety which corresponds to a Mott-type transition at zero temperature. Therefore, these materials form the link between the large family of about fifty low-T unconventional heavy - fermion superconductors and other families of unconventional superconductors with higher Tcs, notably the doped Mott insulators of the cuprates, organic charge-transfer salts and some of the Fe-based superconductors. Our study suggests that heavy-fermion superconductivity near an AF QCP is a robust phenomenon. [ABSTRACT FROM AUTHOR] |
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