Pressure evolution of the low-temperature crystal structure and bonding of the superconductor FeSe ( T c = 37 K )
By S. Margadonna, Y. Takabayashi, Y. Ohishi, Y. Mizuguchi, Y. Takano, T. Kagayama, T. Nakagawa, M. Takata, K. Prassides. 2009
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$\ensuremath{\alpha}\text{-FeSe}$ with the PbO structure is a key member of the family of high-${T}_{c}$ iron pnictide and chalcogenide superconductors, as while it possesses the basic layered structural motif of edge-sharing distorted ${\text{FeSe}}_{4}$ tetrahedra, it lacks interleaved ion spacers or charge-reservoir layers. We find that the application of hydrostatic pressure first rapidly increases ${T}_{c}$ which attains a broad maximum of 37 K at $\ensuremath{\sim}7\text{ }\text{GPa}$ before decreasing to 6 K upon further compression to $\ensuremath{\sim}14\text{ }\text{GPa}$. Complementary synchrotron x-ray diffraction at 16 K was used to measure the low-temperature isothermal compressibility of $\ensuremath{\alpha}\text{-FeSe}$, revealing an extremely soft solid with a bulk modulus, ${K}_{0}=30.7(1.1)\text{ }\text{GPa}$ and strong bonding anisotropy between interlayer and intralayer directions that transforms to the more densely packed $\ensuremath{\beta}$ polymorph above $\ensuremath{\sim}9\text{ }\text{GPa}$. The nonmonotonic ${T}_{c}(P)$ behavior of FeSe coincides with drastic anomalies in the pressure evolution of the interlayer spacing, pointing to the key role of this structural feature in modulating the electronic properties.
Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/52c87793ba043d528c79cc8afa28dda2e92117e3
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Citations in the corpus
- Superconductivity in iron compounds (2011, background): “As mentioned in the Introduction, Margadonna et al. (2009b) found that 7 GPa increases the Tc of FeSe from 8 K at zero pressure up to 37 K, with Tc already 27 K at 2.6 GPa, followed by a decrease down to 6 K as pressure increases to 14 GPa.”
- Colloquium: The unexpected properties of alkali metal iron selenide superconductors (2012, background): “The critical temperature can dramatically increase by Te substitution or even more by pressure up to 37 K (Fang, M. H., et al., 2008 ; Yeh et al., 2008; Margadonna et al., 2009).”