Transport and magnetic properties of EuAl4 and EuGa4

Ai Nakamura, Taro Uejo, Fuminori Honda, Tetsuya Takeuchi, Hisatomo Harima, Etsuji Yamamoto, Yoshinori Haga, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Masato Hedo, Takao Nakama, Yoshichika O'Nuki

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Abstract

We succeeded in growing a single crystal of the Eu-divalent compound EuAl4 with the BaAl4-type tetragonal structure by the Al self-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization, specific heat, and thermoelectric power. EuAl4 orders antiferromagnetically below TN1 = 15.4 K, with three successive antiferromagnetic transitions at TN2 = 13.2 K, TN3 = 12.2 K, and TN4 = 10.0 K. The latter two transitions are of the first-order. The corresponding magnetization curve indicates three successive metamagnetic transitions with hystereses and saturates above 16 kOe. We observed a plausible characteristic feature of the charge density wave (CDW) below TCDW = 140 K. We also studied an effect of pressure on the electronic state by measuring the electrical resistivity and thermoelectric power. TCDW is found to decrease with increasing pressure at a rate of dTCDW/dP = -54.7K/GPa and becomes zero at about 2.5 GPa. The present antiferromagnetic ordering is, however, found to be stable at higher pressures up to 7 GPa in EuAl4. On the other hand, the different characteristic CDW was observed in EuGa4, not at ambient pressure but above 1 GPa, and TCDW increases with increasing pressure. Above 6 GPa, we found that the antiferromagnetic ordering is changed into another first-order-like phase transition. Its characteristic feature is similar to that of the valence transition, and the heavy fermion state is realized at low temperatures.

Original languageEnglish
Article numbere124711
Journaljournal of the physical society of japan
Volume84
Issue number12
DOIs
Publication statusPublished - 2015 Dec 15

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Nakamura, A., Uejo, T., Honda, F., Takeuchi, T., Harima, H., Yamamoto, E., Haga, Y., Matsubayashi, K., Uwatoko, Y., Hedo, M., Nakama, T., & O'Nuki, Y. (2015). Transport and magnetic properties of EuAl4 and EuGa4. journal of the physical society of japan, 84(12), [e124711]. https://doi.org/10.7566/JPSJ.84.124711