Erratum: High-field superconductivity in alloyed Mg B 2 thin films [Phys. Rev. B 71 , 012504 (2005)]

The high field magnetization and magnetotransport measurements are carried out to determine the critical superconducting parameters of MgB 2−x C x system. The synthesized samples are pure phase and the lattice parameter evaluation is carried out using the Rietveld refinement. The R − T͑H͒ measurements are done up to a field of 140 kOe. The upper critical field values, H c2 , are obtained from these data based on the criterion of 90% of normal resistivity, i.e., H c2 = H at which =90% N , where N is the normal resistivity, i.e., resistivity of about 40K in our case. The Werthamer-Helfand-Hohenberg prediction of H c2 ͑0͒ underestimates the critical field value even below the field up to which measurement is carried out. After this model, the Ginzburg-Landau theory is applied to the R − T͑H͒ data which not only calculate the H c2 ͑0͒ value but also determine the dependence of H c2 on temperature in the low temperature high field region. The estimated H c2 ͑0͒ = 157.2 kOe for pure MgB 2 is profoundly enhanced to 297.5 kOe for the x = 0.15 sample in MgB 2−x C x series. Magnetization measurements are done up to 120 kOe at different temperatures and the other parameters such as irreversibility field H irr and critical current density J c ͑H͒ are also calculated. The nano carbon doping results in substantial enhancement of critical parameters such as H c2 , H irr , and J c ͑H͒ in comparison to the pure MgB 2 sample.

Section: Resultsmentioning

confidence: 99%

Enhanced critical parameters of nanocarbon doped MgB2 superconductor

Mudgel

Chandra

Ganesan

et al. 2009

“…which yields 17T, 31T and 25T as H c2 (0) 44,45 . It appears that graphite impurity in MgB 2 grain is enhancing the band scattering leading to increased H c2 values.…”

Section: Fig6 (Color) the Representative Tem Image Of Mgb 2-x C X Wmentioning

confidence: 99%

Enhancement of flux pinning and high critical current density in graphite doped MgB2 superconductor

Shekhar

Giri

Tiwari

et al. 2007

We report the synthesis and characterization of graphite (C) doped MgB 2-x C x (x = 0.0, 0.1, 0.2 and 0.3) samples. The crystal structure and microstructural characterization have been investigated by x-ray diffractometer and transmission electron microscopic (TEM) analysis. The superconducting properties especially J c and H c2 have been measured by employing physical property measurement system. We found that the graphite doping affects the lattice parameters as well as the microstructure of MgB 2 superconductor. In case of optimally doped (x = 0.1) sample, the critical current density at 5K corresponds to 1.1 x 10 6 and 5.3 x 10 4 A/cm 2 for 3T and 5T fields respectively. The upper critical field has been enhanced nearly two times after doping. The flux pinning behavior has been investigated by flux pinning force density curve and it reveals that the flux pinning behaviour has improved significantly by doping. TEM micrographs show the graphite nanoparticles of size ~5-10 nm which are invariably present in MgB 2 grains. These nanoparticles act as flux pinning centre and are responsible for enhancement of superconducting properties of MgB 2 .

“…[1][2][3][4][5][6][7][8][9] Among these, both SiC and C have become well established additives which can result in the enhancement of J c , H irr , and H c2 . The authors' group found that doping of MgB 2 with nanoparticle SiC can significantly enhance J c in high fields, with only slight reductions in T c up to a doping level as high as 30% of B.…”

Section: Introductionmentioning

confidence: 99%

The effect of doping level and sintering temperature on Jc(H) performance in nano-SiC doped and pure MgB2 wires

Shcherbakova

Dou

Soltanian

et al. 2006

Nanoscale SiC doped Fe/ MgB 2 wire samples were prepared by an in situ reaction technique using SiC doping levels of 0, 5, 10, and 15 wt %. Samples were heat treated at different temperatures using different temperature profiles. The effects of doping level and sintering temperature on superconducting properties of wire samples were investigated. The important finding of this study was that the enhancement in J c ͑H͒ by nano-SiC doping can be achieved at different field regions by appropriate compromising of the doping level and sintering temperature.