Anomalous Anisotropy of the Lower Critical Field and Meissner Effect in UTe2
| Autor: | Paulsen, C., Knebel, G., Lapertot, G., Braithwaite, D., Pourret, A., Aoki, D., Hardy, F., Flouquet, J., Brison, J. -P. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 103, 180501 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.103.L180501 |
| Popis: | We report on low temperature susceptibility and magnetization measurements made on single crystals of the recently discovered heavy-fermion superconductor UTe$_2$ and compare the results with the two ambient pressure ferromagnetic superconductors URhGe and UCoGe. Hysteresis curves in the superconducting phase show a familiar diamond shape superimposed on a large paramagnetic background. The Meissner state was measured by zero field cooling in small fields of a few Oe as well as ac susceptibility measurements in small fields and resulted in 100\% shielding, with a sharp transition. However the field cooling Meissner-Ochsenfeld effect (expulsion of flux) was negligible in fields greater than just a few Oe, but becomes nearly 30\% of the perfect diamagnetic signal when the field was reduced to 0.01~Oe. The critical current due to flux pinning was studied by ac susceptibility techniques. Over the range in fields and temperature of this study, no signature of a ferromagnetic transition could be discerned. The lower critical field $H_{\rm c1}$ has been measured along the three crystalographic axes, and surprisingly, the anisotropy of $H_{\rm c1}$ contradicts that of the upper critical field. We discuss this discrepancy and show that it may provide additional support for a magnetic field-dependent pairing mediated by ferromagnetic fluctuations in UTe$_2$. Comment: 5 pages, 4 figures, supplemental material included, to appear in Phys. Rev B (Letter) |
| Databáze: | arXiv |
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