Electronic nematicity above the structural and superconducting transition in BaFe 2 (As 1-xP x) 2

S. Kasahara, H. J. Shi, K. Hashimoto, S. Tonegawa, Y. Mizukami, T. Shibauchi, K. Sugimoto, T. Fukuda, T. Terashima, Andriy H. Nevidomskyy, Y. Matsuda

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387 Citations (Scopus)


Electronic nematicity, a unidirectional self-organized state that breaks the rotational symmetry of the underlying lattice, has been observed in the iron pnictide and copper oxide high-temperature superconductors. Whether nematicity plays an equally important role in these two systems is highly controversial. In iron pnictides, the nematicity has usually been associated with the tetragonal-to-orthorhombic structural transition at temperature T s. Although recent experiments have provided hints of nematicity, they were performed either in the low-temperature orthorhombic phase or in the tetragonal phase under uniaxial strain, both of which break the 90° rotational C 4 symmetry. Therefore, the question remains open whether the nematicity can exist above T s without an external driving force. Here we report magnetic torque measurements of the isovalent-doping system BaFe 2 (As 1-xP x) 2, showing that the nematicity develops well above T s and, moreover, persists to the non-magnetic superconducting regime, resulting in a phase diagram similar to the pseudogap phase diagram of the copper oxides. By combining these results with synchrotron X-ray measurements, we identify two distinct temperatures-one at T*, signifying a true nematic transition, and the other at T s (<T*), which we show not to be a true phase transition, but rather what we refer to as a 'meta-nematic transition', in analogy to the well-known meta-magnetic transition in the theory of magnetism.

Original languageEnglish
Pages (from-to)382-385
Number of pages4
Issue number7403
Publication statusPublished - 2012 Jun 21


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