Electronic states in eucu2(Ge1−xSix)2 based on the doniach phase diagram

Wataru Iha, Tomoyuki Yara, Yousuke Ashitomi, Masashi Kakihana, Tetsuya Takeuchi, Fuminori Honda, Ai Nakamura, Dai Aoki, Jun Gouchi, Yoshiya Uwatoko, Takanori Kida, Time Tahara, Masayuki Hagiwara, Yoshinori Haga, Masato Hedo, Takao Nakama, Yoshichika Onuki

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We succeeded in growing single crystals of EuCu2(Ge1xSix)2 (x = 0–1) by the Bridgman method using a Mo crucible and measured the electrical resistivity, specific heat, magnetic susceptibility, and magnetization, together with the electrical resistivity under pressure. EuCu2(Ge1xSix)2 compounds follow the Doniach phase diagram as a function of the x content. Namely, EuCu2(Ge1xSix)2 compounds exhibit antiferromagnetic ordering at a Néel temperature of TN = 15 K in EuCu2Ge2 (x = 0), a maximum of TN ’ 20 K at x’ 0.5, TN → 0 at x’ 0.7, and a moderate heavy-fermion state at x = 0.8 and 1 (EuCu2Si2). The present result is reasonably consistent with the previous studies carried out using arc-melted polycrystal samples. A similar change in the electronic states was also found to be realized under pressure P for x = 0, 0.45, and 0.6. The Néel temperature of TN = 15 K for x = 0 (EuCu2Ge2) increases slightly as a function of pressure, at a rate of dTN=dP = 3.0 K=GPa, reaches a maximum of TN = 27 K at around 5–6 GPa, decreases steeply, and becomes zero at a critical pressure of Pc ’ 7 GPa. A moderate heavy-fermion state is realized at 8 GPa. Similar results were also obtained for x = 0.45 and 0.6, with smaller critical pressures of Pc ’ 4.5 and 2 GPa, respectively.

Original languageEnglish
Article number064706
JournalJournal of the Physical Society of Japan
Issue number6
Publication statusPublished - 2018


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