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铁基超导体FeSexTe1–x由于其具有上临界场高、各向异性小、临界电流密度大等优点, 备受研究者的广泛关注. 本文采用自助溶剂法生长得到了几种Se/Te组分比例不同的FeSexTe1–x单晶样品, 对其结构和形貌进行了表征, 并且对样品在低温下的磁性进行了测量. 对样品超导态下临界电流密度、磁通钉扎力和磁场的关系进行了分析, 讨论了样品在低温下的磁通钉扎模式. 通过分析Se和Te的不同比例对上述性能的影响, 确定了超导性能最佳的组分, 为今后进一步研究FeSexTe1–x的超导与拓扑性质提供了参考.
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关键词:
- FeSexTe1–x /
- 拓扑超导体 /
- 临界电流密度 /
- 磁通钉扎
Iron-based superconductor FeSexTe1–x has attracted attention because of its high upper critical field, low anisotropy, and high critical current density. Also, it is predicted to have nontrivial topological properties, so that it is a candidate of realizing Majorana fermion, when the superconductivity is combined with topological features. However, its flux pinning behavior and mechanism in superconducting state with varying Se/Te ratio have not been systematically studied . We use self-flux method to grow single crystal samples of FeSexTe1–x with different x values (0.3, 0.4, 0.5 and 0.6). The structural and morphological properties of the monocrystalline samples are characterized by XRD and SEM. All samples show that they possess the expected crystalline structures and their lattice parameters vary with x value. The magnetic properties at low temperatures are also measured, showing that all samples have good superconductivity. Superconducting properties, such as critical current densities and flux pinning force densities, are extracted from the magnetic measurements and analyzed, and the flux pinning behavior is discussed. The best Se:Te ratio is determined to be nearly 0.4/0.6 based on the comparison among these properties of different samples. By utilizing the Dew-Hughes theory and analyzing the pinning force density peak, the flux pinning mechanism in the best samples (x = 0.4, 0.5) can be regarded as the mixture of normal point pinning and Δκvolume pinning. This work provides important information for the further study of the topological and superconducting properties of FeSexTe1–x. -
Keywords:
- FeSexTe1–x /
- topological superconductor /
- flux pinning /
- critical current density
[1] Kamihara Y, Hiramatsu H, Hirano M, Kawamura R, Yanagi H, Kamiya T, Hosono H 2006 J. Am. Chem. Soc. 128 10012Google Scholar
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[8] Fiamozzi Zignani C, De Marzi G, Corato V, Mancini V, Vannozzi A, Rufoloni A, Leo1 V, Guarino A, Galluzzi A, Nigro A, Polichetti M, della Corte A, Pace S, Grimaldi G 2018 J. Mater. Sci. 132 84084
[9] Sun Y, Tsuchiyab Y, Yamadab T, Taenb T, Pyonb S, Shia Z X, Tamegai T 2014 Physica C 113 8656
[10] Abe H, Noji T, Kato M, Koike Y 2010 Physica C 980 8579
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[14] Migita M, Takikawa Y, Takeda M, Uehara M, Kuramoto T, Takano Y, Kimishima Y 2011 Physica C 471 916Google Scholar
[15] Wu Z F, Wang Z H, Tao J, Qiu L, Yang S G, Wen H H 2016 Supercond. Sci. Technol. 29 4
[16] Leo A, Guarino A, Grimaldi G, Nigro A, Pace S, Bellingeri E, Giannini E 2014 J. Phys.: Conf. Ser. 507 012029Google Scholar
[17] Wu Z, Tao J, Xu X, Qiu L, Yang S, Wang Z 2016 Physica C 528 39Google Scholar
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[19] Gomez K W 2010 J. Nov. Magn. 23 551Google Scholar
[20] Imai Y, Sawada Y, Nabeshima F, Maeda A 2015 Proc. Natl. Acad. Sci. 122 193
[21] Wang A F, Ying J J, Yan Y J, Liu R H, Luo X G, Li Z Y, Wang X F, Zhang M, Ye G J, Cheng P, Xiang Z J, Chen X H 2011 Phys. Rev. B 83 060512Google Scholar
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[23] Bean C P 1994 Rev. Mod. Phys. 36 31
[24] Kumar R, Sudesh, Varma G D 2018 Aip. Adv. 8 055819Google Scholar
[25] Bonura M, Giannini E, Viennois R, Senatore C 2012 Phys. Rev. B 85 134532Google Scholar
[26] Shen B, Cheng P, Wang Z S, Fang L, Ren C, Shan L, Gu C Z, Wen H H 2010 Phys. Rev. B 81 014503Google Scholar
[27] Galluzzi A, Buchkov K, Nazarova E, Tomov V, Grimaldi G, Leo A, Pace A, Polichetti M 2018 J. Appl. Phys. 123 233904Google Scholar
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表 1 Fp-h曲线的Dew-Hughes公式拟合参数值
Table 1. Fitted parameters of Fp curves.
T = 2 K T = 4 K p q Fp峰位 p q Fp峰位 x = 0.4 1.647 2.461 0.4013 1.996 2.233 0.4654 x = 0.5 1.632 2.870 0.3552 2.001 2.335 0.4398 -
[1] Kamihara Y, Hiramatsu H, Hirano M, Kawamura R, Yanagi H, Kamiya T, Hosono H 2006 J. Am. Chem. Soc. 128 10012Google Scholar
[2] Kamihara Y, Watanabe T, Hirano M, Hosono H 2008 J. Am. Chem. Soc. 130 3296Google Scholar
[3] Xu G X, Huang H, Zhang X P, Huang S Y, Ma Y M 2018 Acta. Phys. Sin-Ch. Ed. 20 67
[4] Wu Z F, Wang Z H, T ao J, Qiu L, Yang S G, Wen H H 2016 Supercond. Sci. Technol. 29 035006Google Scholar
[5] Tapp J H, Tang Z, Lv B, et al. 2008 Phys. Rev. B 78 060505Google Scholar
[6] Yuan F, Iida K, Grinenko V, Chekhonin P, Pukenas A, Skrotzki W, Sakoda M, Naio M, Sala A, Putti M, Yamashita A, Takano Y, Shi Z, Nielsch K, Hiihne R 2017 Aip. Adv. 7 065015Google Scholar
[7] Bao W, Qiu Y, Huang Q, Green Q M, Zajdel P, Fitzsimmons M R, Zhernenkov M, Chang S, Fang M, Qian Q, Vehstedt E Q, Yang J, Pham H M, Spinu L, Mao Z Q 2009 Phys. Rev. Lett. 102 247001Google Scholar
[8] Fiamozzi Zignani C, De Marzi G, Corato V, Mancini V, Vannozzi A, Rufoloni A, Leo1 V, Guarino A, Galluzzi A, Nigro A, Polichetti M, della Corte A, Pace S, Grimaldi G 2018 J. Mater. Sci. 132 84084
[9] Sun Y, Tsuchiyab Y, Yamadab T, Taenb T, Pyonb S, Shia Z X, Tamegai T 2014 Physica C 113 8656
[10] Abe H, Noji T, Kato M, Koike Y 2010 Physica C 980 8579
[11] Rößler S, Cherian D, Harikrishnan S, Bhat H L, Elizabeth S, Mydosh J A, Tjeng L H, Steglich F, Wirth S 2010 Phys. Rev. B 82 144523Google Scholar
[12] Yadav C S, Paulose P L 2009 New J. Phys. 11 103046Google Scholar
[13] Cieplaka M Z, Bezusyya V L 2015 Philos. Mag. 1478 6435
[14] Migita M, Takikawa Y, Takeda M, Uehara M, Kuramoto T, Takano Y, Kimishima Y 2011 Physica C 471 916Google Scholar
[15] Wu Z F, Wang Z H, Tao J, Qiu L, Yang S G, Wen H H 2016 Supercond. Sci. Technol. 29 4
[16] Leo A, Guarino A, Grimaldi G, Nigro A, Pace S, Bellingeri E, Giannini E 2014 J. Phys.: Conf. Ser. 507 012029Google Scholar
[17] Wu Z, Tao J, Xu X, Qiu L, Yang S, Wang Z 2016 Physica C 528 39Google Scholar
[18] Zhuang J C, Yeoh W K, Cui X Y, Xu X, Du Y, Shi Z X, Ringer P S, Wang X I, Dou S X 2014 Sci. Rep.-Uk. 4 7273
[19] Gomez K W 2010 J. Nov. Magn. 23 551Google Scholar
[20] Imai Y, Sawada Y, Nabeshima F, Maeda A 2015 Proc. Natl. Acad. Sci. 122 193
[21] Wang A F, Ying J J, Yan Y J, Liu R H, Luo X G, Li Z Y, Wang X F, Zhang M, Ye G J, Cheng P, Xiang Z J, Chen X H 2011 Phys. Rev. B 83 060512Google Scholar
[22] Yeh K W, Huang T W, Huang Y I, Chen T K, Hsu F C, Wu P M, Lee Y C, Chu Y Y, Chen C L, Luo J Y, Yan D C, Wu M K 2008 Europhys. Lett. 84 37002Google Scholar
[23] Bean C P 1994 Rev. Mod. Phys. 36 31
[24] Kumar R, Sudesh, Varma G D 2018 Aip. Adv. 8 055819Google Scholar
[25] Bonura M, Giannini E, Viennois R, Senatore C 2012 Phys. Rev. B 85 134532Google Scholar
[26] Shen B, Cheng P, Wang Z S, Fang L, Ren C, Shan L, Gu C Z, Wen H H 2010 Phys. Rev. B 81 014503Google Scholar
[27] Galluzzi A, Buchkov K, Nazarova E, Tomov V, Grimaldi G, Leo A, Pace A, Polichetti M 2018 J. Appl. Phys. 123 233904Google Scholar
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