Magnetic properties and effect of pressure on the electronic state of EuCo2Ge2

Y. Ashitomi, M. Kakihana, F. Honda, A. Nakamura, D. Aoki, Y. Uwatoko, M. Nakashima, Y. Amako, T. Takeuchi, T. Kida, T. Tahara, M. Hagiwara, Y. Haga, M. Hedo, T. Nakama, Y. Ōnuki

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Abstract

EuCo2Ge2 with the tetragonal structure is a Eu-divalent antiferromagnet with the Néel temperature TN=23 K. The magnetic easy-axis corresponds to the [100] direction (a-axis), while the [001] direction (c-axis) is a hard-axis. The magnetization for H∥[100] indicates a metamagnetic transition at 25 kOe and saturates above 75 kOe. On the other hand, the hard-axis magnetization increases approximately linearly and saturates above 110 kOe. The magnetic phase diagram was constructed. A characteristic feature in EuCo2Ge2 is known as a valence transition under pressure, from Eu 2+δ to Eu 3−δ′(δ, δ′<1). We also clarified the valence transition by measuring the electrical resistivity under pressure. The valence transition occurs at 3 GPa, with a hysteresis, and terminates at about 4.5 GPa. Further increasing pressure, the electronic state is changed into a moderate heavy fermion state and approaches the nearly trivalent electronic state.

Original languageEnglish
Pages (from-to)192-196
Number of pages5
JournalPhysica B: Condensed Matter
Volume536
DOIs
Publication statusPublished - 2018 May 1

Keywords

  • EuCoGe
  • High-field magnetization
  • Valence transition

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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    Ashitomi, Y., Kakihana, M., Honda, F., Nakamura, A., Aoki, D., Uwatoko, Y., Nakashima, M., Amako, Y., Takeuchi, T., Kida, T., Tahara, T., Hagiwara, M., Haga, Y., Hedo, M., Nakama, T., & Ōnuki, Y. (2018). Magnetic properties and effect of pressure on the electronic state of EuCo2Ge2 Physica B: Condensed Matter, 536, 192-196. https://doi.org/10.1016/j.physb.2017.09.063