Pressure effect on magnetism and valence in ferromagnetic superconductor Eu(Fe0.75Ru0.25)2As2. (12th October 2022)

• Record Type: Journal Article
• Authors: Nix, Zachary; Zhao, Jiyong; Alp, Esen E; Xiao, Yuming; Zhang, Dongzhou; Cao, Guang-Han; Vohra, Yogesh K; Bi, Wenli
• Is Part Of: Journal of physics. Volume 34:Number 41(2022)
• Publication Date: 2022-10-12
• Subjects: iron pnictide -- magnetism -- pressure -- synchrotron spectroscopy; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ac84bb
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Eu(Fe0.75 Ru0.25 )2 As2 is an intriguing system with unusual coexistence of superconductivity and ferromagnetism, providing a unique platform to study the nature of such coexistence. To establish a magnetic phase diagram, time-domain synchrotron Mössbauer experiments in 151 Eu have been performed on a single crystalline Eu(Fe0.75 Ru0.25 )2 As2 sample under hydrostatic pressures and at low temperatures. Upon compression the magnetic ordering temperature increases sharply from 20 K at ambient pressure, reaching ∼49 K at 10.1 GPa. With further compression, the magnetic order is suppressed and eventually collapses. Isomer shift values from Mössbauer measurements and x-ray absorption spectroscopy data at Eu L 3 edge show that pressure drives Eu ions to a homogeneous intermediate valence state with mean valence of ∼2.4 at 27.4 GPa, possibly responsible for the suppression of magnetism. Synchrotron powder x-ray diffraction experiment reveals a tetragonal to collapsed-tetragonal structural transition around 5 GPa, a lower transition pressure than in the parent compound. These results provide guidance to further work investigating the interplay of superconductivity and magnetism.