High-pressure synthesis of the indirectly electron-doped iron pnictide superconductor Sr1-xLaxFe2As2 with maximum Tc=22 K
High-pressure synthesis of the indirectly electron-doped iron pnictide superconductor Sr1-xLaxFe2As2 with maximum Tc=22 K
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DOI：
10.1103/physrevb.82.180512
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发表时间：
2010-11-17
影响因子：
3.7
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
--
作者：
Muraba, Yoshinori;Matsuishi, Satoru;Hosono, Hideo
在1273 K、2 GPa和3 GPa的压力下，通过固相反应合成了Sr 1-xLaxFe 2As 2化合物。Sr 1-xLaxFe 2As 2相在x=0.5时占主导地位，在x >= 0.2时观察到超导电性。在x=0.4时，最大临界温度Tc为22 K，最大屏蔽体积分数为70%。这是122型铁磷属元素化合物中电子掺杂超导电性的第一个实验证明，其中电子是通过在碱土金属的位置处的异价取代来掺杂的。最佳的Tc比Co掺杂（直接电子掺杂）的样品（19 K）稍高，而比空穴掺杂的样品（37 K）低得多。体超导电性范围比Co取代的情况下窄，并且这两个范围都比空穴掺杂的情况下窄得多。这些观察结果表明，在电子掺杂模式（直接或间接）的差异并没有显着的影响，在最佳的T-c或超导范围相比，在载体极性的差异。
Compounds of Sr1-xLaxFe2As2 were synthesized by solid-state reaction at 1273 K, under pressures of 2 or 3 GPa. The Sr1-xLaxFe2As2 phase was dominant up to x=0.5 and superconductivity was observed at x >= 0.2. A maximum critical temperature T-c of 22 K and a maximum shielding volume fraction of similar to 70% were obtained at x=0.4. This is the first experimental demonstration of electron-doped superconductivity in 122-type iron pnictides, where electrons were doped through aliovalent substitution at the site of the alkaline-earth metal. The optimal T-c was slightly higher than that for the Co-doped (directly electron-doped) samples (19K) and much lower than that for the hole-doped case (37K). The bulk superconductivity range was narrower than that for the Co-substituted case and both ranges were much narrower than that for the hole-doped case. These observations revealed that differences in the electron-doping mode (direct or indirect) did not have a prominent effect on the optimal T-c or superconductivity range, compared with differences in carrier polarity.