Calorimetric evidence for two phase transitions in Ba1-xKxFe2As2 with fermion pairing and quadrupling states

被引：9

作者：

Shipulin, Ilya ^{[1
,2
]}

Stegani, Nadia ^{[3
,4
]}

Maccari, Ilaria ^{[5
,6
]}

Kihou, Kunihiro ^{[7
]}

Lee, Chul-Ho ^{[7
]}

Hu, Quanxin ^{[8
]}

Zheng, Yu ^{[8
]}

Yang, Fazhi ^{[8
]}

Li, Yongwei ^{[8
]}

Yim, Chi-Ming ^{[8
,9
]}

Huehne, Ruben ^{[1
]}

Klauss, Hans-Henning ^{[2
]}

Putti, Marina ^{[3
,4
]}

Caglieris, Federico ^{[3
,4
,10
]}

Babaev, Egor ^{[5
]}

Grinenko, Vadim ^{[8
,9
]}

机构：

[1] Leibniz IFW Dresden, Inst Met Mat, D-01069 Dresden, Germany

[2] Tech Univ Dresden, Inst Solid State & Mat Phys, D-01069 Dresden, Germany

[3] Univ Genoa, Via Dodecaneso 33, I-16146 Genoa, Italy

[4] Consiglio Nazl Ric CNR SPIN, Corso Perrone 24, I-16152 Genoa, Italy

[5] KTH Royal Inst Technol, Dept Phys, SE-10044 Stockholm, Sweden

[6] Paul Scherrer Inst, Lab Theoret & Computat Phys, CH-5232 Villigen, Switzerland

[7] Natl Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki 3058568, Japan

[8] Shanghai Jiao Tong Univ, Tsung Dao Lee Inst, Shanghai 201210, Peoples R China

[9] Shanghai Jiao Tong Univ, Sch Phys & Astron, Shanghai, Peoples R China

[10] IFW Dresden, Leibniz Inst Solid State & Mat Res Dresden, D-01069 Dresden, Germany

来源：

NATURE COMMUNICATIONS | 2023年 / 14卷 / 01期

基金：

瑞典研究理事会;

关键词：

PHASE-DIAGRAM; SUPERCONDUCTIVITY; VORTICES; FLUX; HEAT;

D O I：

10.1038/s41467-023-42459-0

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

Materials that break multiple symmetries allow the formation of four-fermion condensates above the superconducting critical temperature (T-c). Such states can be stabilized by phase fluctuations. Recently, a fermionic quadrupling condensate that breaks the Z(2) time-reversal symmetry was reported in Ba1-xKxFe2As2. A phase transition to the new state of matter should be accompanied by a specific heat anomaly at the critical temperature where Z(2) time-reversal symmetry is broken (T-c(Z2)>T-c). Here, we report on detecting two anomalies in the specific heat of Ba1-xKxFe2As2 at zero magnetic field. The anomaly at the higher temperature is accompanied by the appearance of a spontaneous Nernst effect, indicating the breakdown of Z(2) symmetry. The second anomaly at the lower temperature coincides with the transition to a zero-resistance state, indicating the onset of superconductivity. Our data provide the first example of the appearance of a specific heat anomaly above the superconducting phase transition associated with the broken time-reversal symmetry due to the formation of the novel fermion order.

引用

页数：9

共 44 条

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