3D visualizations of nanoscale phase separation and ultrafast dynamic correlation between phases in (N a0.32 K0.68)0.95 F e1.75 S e2

P. C. Cheng, W. Y. Tzeng, Y. J. Chu, Chih-Wei Luo, A. A. Zhukov, J. Whittaker, Jiunn-Yuan Lin, Kaung-Hsiung Wu, Jenh-Yih Juang, M. Liu, I. V. Morozov, A. I. Boltalin, A. N. Vasiliev

Research output: Contribution to journalArticlepeer-review

Abstract

Phase separation of metallic and antiferromagnetic (AFM) insulating phases in alkaline iron selenides (AxFe2-ySe2) continues to attract intense interest because the relationship between two peculiar features probably is a key to clarifying the pairing mechanism of AxFe2-ySe2 superconductors. Here we report that the three-dimensional (3D) visualizations of nanoscale phase separation in (Na0.32K0.68)0.95Fe1.75Se2 single crystals are revealed by hybrid focused-ion-beam scanning electron microscopy and the superconducting paths are fully percolative in 3D. Moreover, the phase-related ultrafast dynamics in (Na0.32K0.68)0.95Fe1.75Se2 is studied by dual-color pump-probe spectroscopy. The anomalous changes in the electron and acoustic phonon components of transient reflectivity change (ΔR/R) identify two characteristic temperatures T∗∼100K (the onset temperature of coupling between the nanometallic and AFM phases) and TH∼230K (the onset temperature of the metallic-interface phase). An energy-transfer channel between the nanometallic and AFM phases is inferred. This proposed channel provides insight into the pairing mechanism of alkaline iron selenide superconductors.

Original languageEnglish
Article number034802
JournalPhysical Review Materials
Volume3
Issue number3
DOIs
StatePublished - 25 Mar 2019

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