超導體 Mg(0.06)FeTe(1-x)Se(x)  (0≦x≦0.5)

根據X-Ray粉末繞射圖晶體結構數據分析，顯示Mg0.06FeTe1-xSex (0≦x≦0.5)具有Fe1+xTe四方晶體結構，說明了多出來的少量Mg可以用來穩定PbO-type的四方晶體結構。ZFC磁性量測數據顯示Mg0.06FeTe1-xSex (0≦x≦0.5)系列樣品只有在0.4≦x≦0.5時在10.9 K和12.4 K間具有極完美的順磁-超導反磁相變化。由於其低臨界磁場Hc1很小(大約2 Oe)，因此在2 Oe磁場冷卻下所量到之磁化值很小，不像零磁場冷卻下所量到的數據在Tc時，具有明顯的順磁-超導相變化，且在5 K亦有大過100 %之超導相訊號(應該是幾何去磁因素所致)。除此之外，我們也選擇了一個樣品Mg0.06FeTe0.6Se0.4(Tc = 12.4 K)做比熱數據的探討，由於比熱數據最能顯現塊材超導之物理性質，而比熱數據在1.9 K≦T≦30 K 誤差± 1 %下，並沒有看到相變化，說明了在地球磁場(~ 0.5 Oe)冷卻下，超導相無法在比熱數據中清楚觀察到，這個結果與低磁場冷卻下所量到之磁性數據是一致的。此外，利用金屬態之比熱數據T≦10 K時，Cv = γT+βT3，得到Mg0.06FeTe0.5Se0.5樣品之γ = 38.8 mJ/mole．K2，β = 0.783 ± 1% mJ/mole．K4，相當於德拜溫度(Debye Temperature)為178 ±5 K。

關鍵字

鐵基；超導體；磁性；比熱

並列摘要

According to X-Ray powder diffraction pattern crystal structure data analysis and display Mg0.06FeTe1-xSex (0 ≦ x ≦ 0.5) having Fe1 + xTe tetragonal crystal structure, describes the small amount of extra Mg can be used to stabilize the tetragonal PbO-type Crystal structure. ZFC magnetic measurement data Mg0.06FeTe1-xSex (0 ≦ x ≦ 0.5) series of samples only ≦ x ≦ 0.5 having a very perfect paramagnetic at 10.9 K and 12.4 K between 0.4 - superconducting diamagnetic phase change. Because of its low critical magnetic field Hc1 small (about 2 Oe), so in 2 Oe magnetic field cooled magnetization amount to the value of small, unlike the zero field cooling down the amount of data in Tc, the obvious paramagnetic - superconducting phase change, and also at 5 K greater than 100% of the superconducting phase signal (demagnetization factor should be due to geometry). In addition, we selected a sample Mg0.06FeTe0.6Se0.4 (Tc = 12.4 K) do discuss specific heat data, since the specific heat data can best show the physical properties of the bulk superconductivity, and specific heat data at 1.9 K ≦ T ≦ 30 K error of ± 1%, and did not see a phase change, explained in the Earth's magnetic field (~ 0.5 Oe) cooling the superconducting phase can not be clearly observed in the specific heat data, the results under a low magnetic field cooling the amount of the magnetic data are consistent. In addition, the use of specific heat data to the metallic state of T ≦ 10 K, Cv = γT + βT3, obtain samples of γ Mg0.06FeTe0.5Se0.5 = 38.8 mJ / mole. K2, β = 0.783 ± 1% mJ / mole. K4, corresponds to the Debye temperature (Debye Temperature) of 178 ± 5 K.

並列關鍵字

Superconductivty ； specific heat ； Mg ； FeTe ； Se

參考文獻

[1] I. I. Mazin, "Superconductivity gets an iron boost," Nature, vol. 464, pp. 183-186, 2010.

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國際替代計量

超導體 Mg(0.06)FeTe(1-x)Se(x) (0≦x≦0.5)

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