Combined external pressure and Cu-substitution studies on BaFe2As2 single crystals. (19th March 2015)

• Record Type: Journal Article
• Authors: Piva, M M; Besser, M; Mydeen, K; Garitezi, T M; Rosa, P F S; Adriano, C; Grant, T; Fisk, Z; Urbano, R R; Nicklas, M; Pagliuso, P G
• Is Part Of: Journal of physics. Volume 27:Number 14(2015)
• Publication Date: 2015-03-19
• Subjects: superconductivity -- pressure effects -- magnetic pair-breaking; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/27/14/145701
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We report a combined study of external pressure and Cu-substitution on BaFe2 As2 single crystals grown by the in-flux technique. At ambient pressure, the Cu-substitution is known to suppress the spin density wave (SDW) phase in pure BaFe2 As2 ( T SDW ≈ 140 K) and to induce a superconducting (SC) dome with a maximum transition temperature . This is much lower than the T c ∼ 15–28 K achieved in the case of Ru, Ni and Co substitutions. Such a lower T c is attributed to a Cu 2+ magnetic pair-breaking effect. The latter is strongly suppressed by applied pressure, as shown herein, T c can be significantly enhanced by applying high pressures. In this work, we investigated the pressure effects on Cu 2+ magnetic pair-breaking in the BaFe2− x Cu x As2 series. Around the optimal concentration ( x opd = 0.11), all samples showed a substantial increase of T c as a function of pressure. Yet for those samples with a slightly higher doping level (over-doped regime), T c presented a dome-like shape with maximum T c ≃ 8 K. Remarkably interesting, the under-doped samples, e.g. x = 0.02 display a maximum pressure induced T c ≃ 30 K which is comparable to the maximum T c 's found for the pure compound under external pressures. Furthermore, the magnetoresistance effect as a function of pressure in the normal state of the x = 0.02 sample also presented an evolution consistent with the screening of the Cu 2+ local moments. These findings demonstrate that the Cu 2+ magnetic pair-breaking effect is completely suppressed by applying pressure in the low concentration regime of Cu 2+ substituted BaFe2 As2 .