Gap structure of FeSe determined by field-angle-resolved specific heat measurements
| Autor: | Sun, Yue, Kittaka, Shunichiro, Nakamura, Shota, Sakakibara, Toshiro, Irie, Koki, Nomoto, Takuya, Machida, Kazushige, Chen, Jingting, Tamegai, Tsuyoshi |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 96, 220505 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.96.220505 |
| Popis: | Quasiparticle excitations in FeSe were studied by means of specific heat ($C$) measurements on a high-quality single crystal under rotating magnetic fields. The field dependence of $C$ shows three-stage behavior with different slopes, indicating the existence of three gaps ($\Delta_1$, $\Delta_2$, and $\Delta_3$). In the low-temperature and low-field region, the azimuthal-angle ($\phi$) dependence of $C$ shows a four-fold symmetric oscillation with sign change. On the other hand, the polar-angle ($\theta$) dependence manifests as an anisotropy-inverted two-fold symmetry with unusual shoulder behavior. Combining the angle-resolved results and the theoretical calculation, the smaller gap $\Delta_1$ is proved to have two vertical-line nodes or gap minima along the $k_z$ direction, and is determined to reside on the electron-type $\varepsilon$ band. $\Delta_2$ is found to be related to the electron-type $\delta$ band, and is isotropic in the $ab$-plane but largely anisotropic out of the plane. $\Delta_3$ residing on the hole-type $\alpha$ band shows a small out-of-plane anisotropy with a strong Pauli-paramagnetic effect. Comment: 6 pages, 3 figures |
| Databáze: | arXiv |
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