Evolution of superconductivity in isovalent Te-substituted KxFe2−ySe2 crystals
Evolution of superconductivity in isovalent Te-substituted KxFe2−ySe2 crystals
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DOI：
10.1088/0953-2048/26/5/055002
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发表时间：
2012-09
影响因子：
3.6
通讯作者：
T. Ozaki;H. Takeya;K. Deguchi;S. Demura;H. Hara;Tohru Watanabe;Saleem James Denholme;H. Okazaki-H.-Okazak
中科院分区：
文献类型：
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作者：
T. Ozaki;H. Takeya;K. Deguchi;S. Demura;H. Hara;Tohru Watanabe;Saleem James Denholme;H. Okazaki-H.-Okazak
本文报道了一步法生长的K_xFe_2-−_ySe_2-−_zTez(z=0-0.6)晶体的超导电性演化和相图。一步合成法比传统的生长KxFe2−ySe2体系的工艺简单得多。没有观察到任何晶体的结构转变，而晶格参数随着Te含量的增加呈现出系统的膨胀。从T_c=3.2开始，T_c随Te含量的增加而逐渐减小。在z=0到T_c_0=27处。在z=0.5时，超导电性突然被抑制。当Te浓度接近0.6时，屏蔽体积分数减小，最终降至零。同时，ρ-T曲线中的驼峰位置向较低温度移动。这些结果表明，KxFe2−ySe2晶体中Te对Se的等价取代抑制了该体系的超导电性。
We report the evolution of superconductivity and the phase diagram of the KxFe2−ySe2−zTez (z = 0–0.6) crystals grown by a one-step synthesis. The one-step synthesis is much simpler than a conventional process to grow the KxFe2−ySe2 system. No structural transition is observed in any crystals, while lattice parameters exhibit a systematic expansion with increasing Te content. The Tc exhibits a gradual decrease with increasing Te content from T c onset = 3 2 . 9?> K at z = 0 to T c zero = 2 7 . 9?> K at z = 0.5, followed by a sudden suppression of superconductivity at z = 0.6. Upon approaching a Te concentration of 0.6, the shielding volume fraction decreases and eventually drops to zero. Simultaneously, hump positions in the ρ–T curve shift to lower temperatures. These results suggest that isovalent substitution of Te for Se in KxFe2−ySe2 crystals suppresses the superconductivity in this system.