Low temperature structural anomalies arising from competing exchange interactions in pyrochlore Nd2Ru2O7 probed by XRD and EXAFS

Shi Wei Chen, Shao Wei Fu, Chih Wen Pao, Jenn Min Lee, Shin An Chen, Shu Chih Haw, Jyh Fu Lee, Chun Hsia Liu, Chung Kai Chang, Yu Chun Chuang, Hwo Shuenn Sheu, Kueih Tzu Lu, Szu Tu Ku, Lieh Jeng Chang, Jin Ming Chen

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3 Citations (Scopus)

Abstract

Quantitative structural parameters of pyrochlore Nd2Ru2O7, with temperature dependence, have been derived upon fitting XRD and EXAFS data. An anomalous expansion of the lattice parameter and the Ru-O bond length indicates a structural instability at low temperatures; in particular, an increase in the non-thermal term of the mean square fluctuation in the bond length is the evidence for a static disorder of Ru atoms. This static disorder is closely correlated with a decrease in the average Ru-O-Ru bond angle with decreasing temperature, favoring the short-range ferromagnetic coupling in the material. This ferromagnetic coupling formed thus triggered the spin frustration at low temperature when the contradictory constraints of antiferromagnetic interaction act upon the same Ru site in the corner-sharing tetrahedrons of pyrochlore Nd2Ru2O7. This study demonstrates that the spin frustration arising from the competition of ferromagnetic/antiferromagnetic interactions in pyrochlore Nd2Ru2O7 will cause structural instability especially on the atomic scale, which provides a new point of view to help understand its particular magnetic state.

Original languageEnglish
Pages (from-to)23667-23673
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number36
DOIs
Publication statusPublished - 2015 Aug 12

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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    Chen, S. W., Fu, S. W., Pao, C. W., Lee, J. M., Chen, S. A., Haw, S. C., Lee, J. F., Liu, C. H., Chang, C. K., Chuang, Y. C., Sheu, H. S., Lu, K. T., Ku, S. T., Chang, L. J., & Chen, J. M. (2015). Low temperature structural anomalies arising from competing exchange interactions in pyrochlore Nd2Ru2O7 probed by XRD and EXAFS. Physical Chemistry Chemical Physics, 17(36), 23667-23673. https://doi.org/10.1039/c5cp03340c