کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1819125 | 1525762 | 2009 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Specific heat and phase diagrams of single crystal iron pnictide superconductors
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We present specific heat measurements on single crystals of the pnictide superconductors NdFeAsO1âxFx and Ba1âxKxFe2As2. Low-temperature measurements on Ba1âxKxFe2As2 reveal that the Sommerfeld coefficient of the quasiparticle specific heat increases linearly with applied magnetic field. This is the signature of a fully gapped superconducting state as is expected for instance in the extended s-wave scenario. The large value of the normal state Sommerfeld coefficient indicates a large electronic density of states and significant mass enhancements. We determine the phase diagram using an entropy conserving construction, which does not require the choice of a resistivity criterion to define the transition temperature. Both materials display clear mean-field steps in the specific heat at Tc of 47 K and 34.6 K, respectively, proving bulk superconductivity. They are characterized by a low superconducting anisotropy near Tc of Πâ¼Â 4 for NdFeAsO1âxFx and 2.6 for Ba1âxKxFe2As2, which is promising for potential applications. We observe extraordinarily high upper critical field slopes of μ0âHc2c/âT=-6.5T/K and μ0âHc2ab/âT=-17.4T/K for Ba1âxKxFe2As2 which points to the emergence of paramagnetic limiting effects at low temperatures. A thermodynamic analysis reveals that this material is extreme type-II with κc â¼Â 100 and κab â¼Â 260.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physica C: Superconductivity - Volume 469, Issues 9â12, 1 Mayâ15 June 2009, Pages 575-581
Journal: Physica C: Superconductivity - Volume 469, Issues 9â12, 1 Mayâ15 June 2009, Pages 575-581
نویسندگان
U. Welp, G. Mu, R. Xie, A.E. Koshelev, W.K. Kwok, H.Q. Luo, Z.S. Wang, P. Cheng, L. Fang, C. Ren, H.-H. Wen,