تقرير
Calorimetric evidence for two phase transitions in Ba$_{\rm 1-x}$K$_{\rm x}$Fe$_{2}$As$_{2}$ with fermion pairing and quadrupling states
| العنوان: | Calorimetric evidence for two phase transitions in Ba$_{\rm 1-x}$K$_{\rm x}$Fe$_{2}$As$_{2}$ with fermion pairing and quadrupling states |
|---|---|
| المؤلفون: | Shipulin, Ilya, Stegani, Nadia, Maccari, Ilaria, Kihou, Kunihiro, Lee, Chul-Ho, Li, Yongwei, Hühne, Ruben, Klauss, Hans-Henning, Putti, Marina, Caglieris, Federico, Babaev, Egor, Grinenko, Vadim |
| المصدر: | Nat Commun 14, 6734 (2023) |
| سنة النشر: | 2022 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons |
| الوصف: | Theoretically, materials that break multiple symmetries allow, under certain conditions, the formation of four-fermion condensates above the superconducting critical temperature. Such states can be stabilized by phase fluctuations. Recently a fermionic quadrupling condensate that breaks the $Z_2$ time-reversal symmetry was reported in Ba$_{\rm 1-x}$K$_{\rm x}$Fe$_{2}$As$_{2}$ [V. Grinenko et al., Nat. Phys. 17, 1254 (2021)]. Evidence for the new state of matter comes from muon-spin rotation, transport, thermoelectric, and ultrasound experiments. Observing a specific heat anomaly is a very important signature of a transition to a new state of matter. However, a fluctuation-induced specific heat singularity is usually very challenging to resolve from a background of other contributions. Here, we report on detecting two anomalies in the specific heat of Ba$_{\rm 1-x}$K$_{\rm x}$Fe$_{2}$As$_{2}$ at zero magnetic field. The anomaly at the higher temperature is accompanied by the appearance of a spontaneous Nernst effect, indicating broken time-reversal ($Z_2$) symmetry. The second anomaly at the lower temperature coincides with the transition to a zero resistance state, indicating superconductivity breaking the $U(1)$ gauge symmetry. Our data provide calorimetric evidence for the $Z_2$ phase formation above the superconducting phase transition. Comment: 12 pages, 3 figures and Supplementary information |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1038/s41467-023-42459-0 |
| URL الوصول: | http://arxiv.org/abs/2212.13515 |
| رقم الأكسشن: | edsarx.2212.13515 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1038/s41467-023-42459-0 |
|---|