Successful Observation of High Pressure-Induced Changes in Electronic State and Lattice Vibration in an Iron-based High-Temperature Superconductor (Press Release)

Release Date: 16 Jan, 2013

BL09XU (Nuclear Resonant Scattering)

-A clue in the search for the superconductivity expression mechanism of iron-based materials-

University of Hyogo
Japan Synchrotron Radiation Research Institute

A group of researchers from three organizations - University of Hyogo, Japan Synchrotron Radiation Research Institute (JASRI), and Japan Atomic Energy Agency (JAEA) - conducted a nuclear resonance inelastic scattering^*1 study on iron-based high-temperature superconductors, using the high-intensity X-ray available at SPring-8. The study led to successful observations of pressure-induced lattice vibration and the electronic state of iron atoms in iron-based high-temperature superconducting materials.^*2 The study revealed, for the first time in the world, that the change in electronic hybridization of orbital electrons between the arsenic atoms, which normally accompanies changes in electronic states of iron atoms, has a strong implication in the expression mechanism of high-temperature superconductivity in iron-based materials.

The research results first appeared in the on-line version of Journal of Physics: Condensed Matter on the 5th of December, 2012, published by the Institute of Physics (IOP). They were then published in the latest print issue (Jan. 16, 2013) and selected as one of the IOP Selects.^*3

Publication:
"Observation of a pressure-induced As-As hybridization associated with a change in the electronic state of Fe in the tetragonal phase of EuFe₂As₂"
Hisao Kobayashi, Shugo Ikeda, Yui Sakaguchi, Yoshitaka Yoda, Hiroki Nakamura and Masahiko Machida
Journal of Physics: Condensed Matter, 25 (2013) 022201

<<Figures>>

Fig. 1 Nuclear resonant inelastic scattering spectra: under normal and extreme pressure (33 × 103 atom.)

Fig. 1 Nuclear resonant inelastic scattering spectra: under normal and extreme pressure (33 × 10³ atom.)

The black dots represent measured data, and the red solid line represents the calculated inelastic component. The solid red line consists of phonon processes - a single phonon, double-phonon, and multi-phonon - represented by a type of blue liners. Large variations in excitation probability are apparent at ±10 meV, which represent the changes in lattice vibration.

Fig. 2 Atomic arrangement of EuFe2As2, as seen from the a-axis direction of the tetragonal system.

Fig. 2 Atomic arrangement of EuFe₂As₂, as seen from the a-axis direction of the tetragonal system.

The arrow in the figure indicates displacement of an arsenic atom caused by the shifted hybridization state in orbital electrons.

<<Glossary>>
*1 Nuclear resonant inelastic scattering
A type of resonant inelastic scattering induced by the irradiation of a synchrotron radiation X-ray, normally accompanying nuclear recoil. In an inelastic scattering, the scattered X-ray has a different wavelength from that of the incident X-ray.

*2 Iron-based high-temperature superconductor
A new type of high-temperature superconductors discovered in Japan in 2008. The discovery gained special attention because it defied the conventional theory that compounds based on ferromagnetic substances (i.e. iron-based compounds) were incapable of exhibiting superconducting properties. However, the detailed mechanism for superconductivity manifestation has not been elucidated.

*3 IOP Select
The editors of the Institute of Physics (a physics association in the U.K. and Ireland) annually select a set of papers (IOP Select) from those published during the year based on novelty and breakthrough that stand out from the current standard of research, and have the potential to influence future research.

For more information, please contact:
Prof. Hisao Kobayashi (University of Hyogo)
E-mail : mail1

Previous Article: Elucidation of the Rotation Mechanism of the Molecular Motor, Which is Implicated in Osteoporosis and Cancer Metastasis (Press Release)

Current article: Successful Observation of High Pressure-Induced Changes in Electronic State and Lattice Vibration in an Iron-based High-Temperature Superconductor (Press Release)

Next Article: The World’s First Successful Internal Structure Analysis of Drug Delivery Nanoparticles (Press Release)

SPring-8, the large synchrotron radiation facility

Personal tools

Navigation

Successful Observation of High Pressure-Induced Changes in Electronic State and Lattice Vibration in an Iron-based High-Temperature Superconductor (Press Release)