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We investigate the electronic properties and the superconducting gap characteristics of a single crystal of hole-doped 122 Fe-pnictide Ba$_{0.65}$Na$_{0.35}$Fe$_2$As$_2$ by means of specific heat measurements. The specific heat exhibits a…

Superconductivity · Physics 2011-08-29 A. K. Pramanik , M. Abdel-Hafiez , S. Aswartham , A. U. B. Wolter , S. Wurmehl , V. Kataev , B. Büchner

Monocore powder-in-tube MgB2 strands were cold-drawn and heat-treated at 600C and 700C for times of up to 71 hours and structure-property relationships examined. Drawing-induced elongation of the Mg particles led, after HT, to a textured…

Superconductivity · Physics 2015-05-30 M. A. Susner , T. W. Daniels , M. D. Sumption , E. W. Collings

This review paper illustrates the main normal and superconducting state properties of magnesium diboride, a material known since early 1950's, but recently discovered to be superconductive at a remarkably high critical temperature Tc=40K…

Superconductivity · Physics 2007-05-23 Cristina Buzea , Tsutomu Yamashita

Single-crystals of the new ferromagnetic superconductor UCoGe have been grown. The quality of as-grown samples can be significantly improved by a heat-treatment procedure, which increases the residual resistance ratio (RRR) from ~5 to ~30.…

Strongly Correlated Electrons · Physics 2015-05-13 N. T. Huy , Y. K. Huang , A. de Visser

We examine the Mn concentration dependence of the electronic and magnetic properties of optimally annealed Ga1-xMnxAs epilayers for 1.35% < x < 8.3%. The Curie temperature (Tc), conductivity, and exchange energy increase with Mn…

Condensed Matter · Physics 2009-11-07 S. J. Potashnik , K. C. Ku , R. Mahendiran , S. H. Chun , R. F. Wang , N. Samarth , P. Schiffer

The fabrication, characterisation, and superconductivity of MgB2 thick films grown on stainless steel substrate were studied. XRD, SEM, and magnetic measurements were carried out. It was found that the MgB2 thick films can be fast formed by…

Superconductivity · Physics 2007-05-23 A. H. Li , X. L. Wang , M. Ionescu , S. Soltonian , J. Horvat , T. Silver , H. K. Liu , S. X. Dou

The effects of Fe-ion irradiation on the crystal structure and superconducting properties of MgB$_2$ thin films were investigated. Pristine samples were prepared using hybrid physical-chemical vapor deposition (HPCVD), and ion irradiation…

Among the large class of Heusler compounds, Co2CrAl is predicted to be 100 % spin polarized and is hence, a potential candidate for application in spintronics. So far, the predicted properties have not been experimentally realized which may…

Materials Science · Physics 2017-01-04 Ahmad Omar , Christian G. F. Blum , Wolfgang Löser , Bernd Büchner , Sabine Wurmehl

Heat capacity, magnetic susceptibility, NMR, and resistivity of SrNi2P2 single crystals are presented, illustrating a purely structural transition at 325 K with no magnetism. Bulk superconductivity is found at 1.4 K. The magnitude of the…

Superconductivity · Physics 2009-04-13 F. Ronning , E. D. Bauer , T. Park , S. -H Baek , H. Sakai , J. D. Thompson

We investigated the occurrence and nature of superconductivity in single crystals of YFe$_2$Ge$_2$ grown out of Sn flux by employing x-ray diffraction, electrical resistivity, and specific heat measurements. We found that the residual…

Superconductivity · Physics 2015-06-22 H. Kim , S. Ran , E. D. Mun , H. Hodovanets , M. A. Tanatar , R. Prozorov , S. L. Bud'ko , P. C. Canfield

Considerable excitement has been caused recently by the discovery that the binary boride system with stoichiometry MgB2 is superconducting at the remarkably high temperature of 39 K (1). This potentially opens the way to even higher Tc…

The physical property characterization of Al doped Mg1-xAlxB2 system with x = 0.0 to 0.50 is reported. The results related to phase formation, structural transition, resistivity R(T) and magnetization M(T) measurements are discussed in…

Superconductivity · Physics 2012-01-24 Monika Mudgel , V. P. S. Awana , H. Kishan , G. L. Bhalla

We have studied the structural and electronic properties of Mg(1-x)Al(x)B2 within the Virtual Crystal Approximation (VCA) by means of first-principles total-energy calculations. Results for the lattice parameters, the electronic band…

Superconductivity · Physics 2009-11-07 O. de la Pena , A. Aguayo , R. de Coss

Hydrogenation of MgB_2 powder has lead to an increase in the superconducting temperature, as determined by ac susceptibility. Applied dc fields reduce the transition temperature in the same ratio as for the pure powder.

Superconductivity · Physics 2007-05-23 V. V. Flambaum , G. A. Stewart , G. J. Russell , J. Horvat , S. X. Dou

We have studied thermodynamics of the Mg-B system with the modeling technique CALPHAD using a computerized optimization procedure. Temperature-composition, pressure-composition, and pressure-temperature phase diagrams under different…

Materials Science · Physics 2009-11-07 Zi-Kui Liu , D. G. Schlom , Qi Li , X. X. Xi

AC losses of granular superconducting MgB2 were measured using non-resonant rf power absorption techniques. The presence of two band-gaps makes the temperature dependent ac loss pattern of MgB2 different from other high Tc superconductors…

Superconductivity · Physics 2007-05-23 S. Sarangi , S. P. Chockalingam , S. V. Bhat

X-ray diffraction multipole refinements of single-crystalline Mg$_x$Al$_{1-x}$B$_2$ and polarization-dependent near-edge x-ray absorption fine structure at the B 1$s$ edge reveal a strongly anisotropic electronic structure. Comparing the…

Superconductivity · Physics 2016-04-01 M. Merz , P. Schweiss , Th. Wolf , H. v. Löhneysen , S. Schuppler

We studied the effect of disorder on the superconducting properties of polycrystalline MgB_2 by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with…

We studied the temperature and the angular dependences of the upper critical field ($H_{c2}(T,\theta$)) of Mg$_{1-x}$Al$_x$B$_2$ single crystals ($x = 0.12$ and 0.21) and compared with the dirty-limit two-gap theory. We found that…

Superconductivity · Physics 2007-05-23 Heon-Jung Kim , Hyun-Sook Lee , Byeongwon Kang , Woon-Ha Yim , Younghun Jo , Myung-Hwa Jung , Sung-Ik Lee

The temperature dependence of the upper critical field, Hc2, for both field directions in partially substituted polycrystalline MgB2 was determined. Whereas the suppression of Tc is similar for aluminum and carbon substituted samples, Hc2…

Superconductivity · Physics 2008-11-28 M. Angst , S. L. Bud'ko , R. H. T. Wilke , P. C. Canfield