Pressure-induced changes in the magnetic and valence state of EuFe2As2
Pressure-induced changes in the magnetic and valence state of EuFe2As2
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DOI：
10.1103/physrevb.84.024502
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发表时间：
2011-07-05
影响因子：
3.7
通讯作者：
Uwatoko, Y.
中科院分区：
文献类型：
--
作者：
Matsubayashi, K.;Munakata, K.;Uwatoko, Y.
本文给出了三元砷化铁EuFe2As2单晶在加压下的电阻率、交流比热、磁化率、X射线吸收光谱(XAS)和X射线磁性圆二色谱(XMCD)的结果。加压使与Fe磁矩相关的反铁磁性持续受到抑制，在接近2.5-2.7 Gpa的临界压力P-c附近，反铁磁转变温度变为零。由于Eu~(2+)磁矩的反铁磁有序和超导电性的竞争，压力诱导重入超导电性只出现在P-c附近的窄压区，对压力的均匀性高度敏感。Eu2+磁矩的反铁磁态在6 Gpa以上转变为铁磁态。我们还发现，随着压强的进一步增加，铁磁有序被抑制，这与Eu离子的价态变化有关。
We present the results of electrical resistivity, ac specific heat, magnetic susceptibility, x-ray absorption spectroscopy (XAS), and x-ray magnetic circular dichroism (XMCD) of the ternary iron arsenide EuFe2As2 single crystal under pressure. Applying pressure leads to a continuous suppression of the antiferromagnetism associated with Fe moments and the antiferromagnetic transition temperature becomes zero in the vicinity of a critical pressure P-c similar to 2.5-2.7 GPa. Pressure-induced reentrant superconductivity, which is highly sensitive to the homogeneity of the pressure, only appears in the narrow pressure region in the vicinity of P-c due to the competition between superconductivity and the antiferromagnetic ordering of Eu2+ moments. The antiferromagnetic state of Eu2+ moments changes to the ferromagnetic state above 6 GPa. We also found that the ferromagnetic order is suppressed with further increasing pressure, which is connected with a valence change of Eu ions.