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Upper critical fields in Ba2Ti2Fe2As4O single crystals: Evidence for dominant Pauli paramagnetic effectстатья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или Scopus- Авторы: Abdel-Hafiez M., Brisbois J., Zhu Z., Hassen A., Vasiliev A.N., Silhanek A.V., Krellner and C.
- Журнал: Physical Review B
- Год издания: 2018
- Издательство: American Physical Society
- Местоположение издательства: United States
- DOI: 10.1103/PhysRevB.00.005100
- Аннотация: We report on magneto-optical imaging and the temperature dependency of the upper critical fields Hc c2 1 (T )parallel to the c axis and Hab c2 (T ) parallel to the ab plane in Ba2Ti2Fe2As4O single crystals. These data were inferred from the measurements of the temperature-dependent resistance in static magnetic fields up to 14 T and magnetoresistance in pulsed fields up to 60 T. Hc2 values are found to be 52 and 50 T for H ab and H c, respectively. These values are 1.2–1.35 times larger than the weak-coupling Pauli paramagnetic limit (Hp ∼ 1.84Tc), indicating that enhanced paramagnetic limiting is essential and this superconductor is unconventional. Our observations of strong bending in the Hab c2 (T ) curves and a nearly isotropic maximum upper critical field Hab c2 (0) ≈ Hc c2(0) support the presence of a strong Pauli paramagnetic effect. We show that the Werthamer-Helfand-Hohenberg (WHH) formula that includes the spin-orbit scattering can effectively describe the Hab c2 (T ) curve, whereas Hc2 deviates from the conventional WHH theoretical model without considering the spin paramagnetic effect for the H c and H ab directions. For H c, a two-band model is required to fully reproduce the behavior of Hc2, while for H ab the spin paramagnetic effect is responsible for the behavior of Hc2. The anisotropy of Hc2 is close to 3 near Tc and decreases rapidly at lower temperatures.
- Добавил в систему: Васильев Александр Николаевич