Enhancement of superconductivity in FeSe thin crystals induced by biaxial compressive strain

• Published in: Physica. C, Superconductivity Vol. 537; pp. 1 - 4
• Main Authors: Wang, X.F., Zhang, Z.T., Wang, W.K., Zhou, Y.H., Kan, X.C., Chen, X.L., Gu, C.C., Zhang, L., Pi, L., Yang, Z.R., Zhang, Y.H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.06.2017; Elsevier BV
• Subjects: Biaxial compressive strains; Compressive properties; Critical field (superconductivity); Crystals; FeSe; Iron; Iron compounds; Strain; Superconductivity; Transition temperature; FeSe; Biaxial compressive strains; Superconductivity
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2017.02.004

•Biaxial compressive strain effect on FeSe thin crystals.•A notable enhancement of superconductivity in FeSe.•An increase of the onset temperature of enhanced spin fluctuations in FeSe.•A suppression of the structural/nematic transition temperature in FeSe. We report on the enhancement of superconductivity in FeSe thin crystals induced by in-plane biaxial compressive strain, with an underlying scotch tape as an in-situ strain generator. It is found that, due to the compressive strain, the superconducting transition temperature Tc ≈ 9 K of FeSe is increased by 30%–40% and the upper critical field Hc2(0) ≈ 14.8 T is increased by ∼ 20%. In parallel, the T*, which characterizes an onset of enhanced spin fluctuations, is raised up from 69 K to 87 K. On the other hand, the structural transition temperature Ts ≈ 94 K, below which an orthorhombic structure and an electronic nematic phase settle in, is suppressed down by ∼ 5 K. These findings reveal clear evolutions of the orders/fluctuations under strain effect in FeSe, the structurally simplest iron-based superconductor where the lattice/spin/charge degrees of freedom are closely coupled to one another. Moreover, the presented research provides a simple and clean way to manipulate the superconductivity in the layered iron compounds and may promote applications in related materials.