74 citations · 638 across the 35 of their papers we have counts for
26 papers · 1 filter
Nb-substitution suppresses the superconducting critical temperature of pressurized MoB
J. Lim, S. Sinha, A. C. Hire +9
A recent work has demonstrated that MoB, transforming to the same structure as MgB (), superconducts at temperatures above 30 K near 100 GPa [C. Pei . Natl…
High critical field superconductivity at ambient pressure in MoB stabilized in the P6/mmm structure via Nb substitution
A. C. Hire, S. Sinha, J. Lim +7
Recently it was discovered that, under elevated pressures, MoB exhibits superconductivity at a critical temperature, , as high as 32 K. The superconductivity appears to de…
Creating superconductivity in WB2 through pressure-induced metastable planar defects
J. Lim, A. C. Hire, Y. Quan +11
High-pressure electrical resistivity measurements reveal that the mechanical deformation of ultra-hard WB2 during compression induces superconductivity above 50 GPa with a maximum…
Machine learning of superconducting critical temperature from Eliashberg theory
S. R. Xie, Y. Quan, A. C. Hire +11
The Eliashberg theory of superconductivity accounts for the fundamental physics of conventional electron-phonon superconductors, including the retardation of the interaction and th…
High pressure study of low-Z superconductor BeRe
J. Lim, A. C. Hire, Y. Quan +11
With , BeRe exhibits one of the highest critical temperatures among Be-rich compounds. We have carried out a series of high-pressure electrical resi…
Unusual Sensitivity of Superconductivity to Strain in Iron-Based 122 Superconductors
J. S. Kim, G. N. Tam, G. R. Stewart
Co-doped BaFe2As2 has been previously shown to have an unusually significant improvement of Tc (up to 2 K, or almost 10%) with annealing 1-2 weeks at 700 or 800 C, where such annea…
Specific Heat of Ca0.33Na0.67Fe2As2
J. S. Kim, K. Zhao, C. Q. Jin +1
The specific heat of single crystal hole-doped Ca0.33Na0.67Fe2As2, Tc(onset)=33.7 K, was measured from 0.4 to 40 K. The discontinuity in the specific heat at Tc, deltaC, divided by…
Plane Point Contact Spectroscopy measurements of optimally Cobalt doped Ba-122 iron-pnictide superconductors
John Timmerwilke, E. Kim, J. Maughan +3
Point contact spectroscopy (PCS) is a technique which can reveal the size and symmetry of a superconducting gap () and is especially useful for new materials such as the iron-ba…
Specific Heat vs Field of LiFe1-xCuxAs
J. S. Kim, G. R. Stewart, L. Y. Xing +2
LiFeAs is one of the new class of iron superconductors with a bulk onset Tc in the 15-17 K range. We report on the specific heat characterization of single crystal material prepare…
Specific Heat Discontinuity DeltaC vs Tc in Annealed Ba(Fe1-xCox)2As2
J. S. Kim, B. D. Faeth, G. R. Stewart
The low temperature specific heat of annealed single crystal samples of Ba(Fe1-xCox)2As2 with compositions spanning the entire superconducting phase diagram was measured. Effort wa…
Specific Heat Discontinuity, deltaC, at Tc in BaFe2(As0.7P0.3)2 - Consistent with Unconventional Superconductivity
J. S. Kim, G. R. Stewart, S. Kasahara +3
We report the specific heat discontinuity, deltaC/Tc, at Tc = 28.2 K of a collage of single crystals of BaFe2(As0.7P0.3)2 and compare the measured value of 38.5 mJ/molK**2 with oth…
Specific heat in KFe2As2 in zero and applied magnetic field
J. S. Kim, E. G. Kim, G. R. Stewart +2
The specific heat down to 0.08 K of the iron pnictide superconductor KFe2As2 was measured on a single crystal sample with a residual resistivity ratio of ~650, with an onset Tc det…
Specific Heat vs Field in the 30 K Superconductor BaFe2(As0.7P0.3)2
J. S. Kim, P. J. Hirschfeld, G. R. Stewart +4
We report specific heat measurements on the Fe-based superconductor BaFe2(As0.7P0.3)2, a material on which previous penetration depth, NMR, and thermal conductivity measurements ha…
Dual Character of Magnetism in Ferropnictides: Insights from Optical Measurements
S. J. Moon, J. H. Shin, D. Parker +10
We investigate the electronic structure of EuFeAs using optical spectroscopy and first-principles calculations. At low temperature we observe the evolution of \textit{t…
Superconductivity in Undoped Single Crystals of BaFe2As2: Field and Current Dependence
J. S. Kim, T. D. Blasius, E. G. Kim +1
In previous work in undoped MFe2As2, partial drops in the resistivity indicative of traces of superconductivity have been observed in some samples of M=Ba (Tc ~ 20 K, up to 25% dro…
Spontaneous stoichiometry change in a single crystal of (Ba1-x Kx)Fe2As2 produced by rapid heating method
P. Reuvekamp, F. S. Razavi, C. Hoch +3
To prevent the loss of K in growing single crystals of Ba1-x Kx Fe2 As2 we developed a rapid heating Sn-flux method. Large single crystals with the optimal superconducting transiti…
Point-contact Andreev-reflection spectroscopy in ReFeAsO_{1-x}F_x (Re = La, Sm): Possible evidence for two nodeless gaps
R. S. Gonnelli, D. Daghero, M. Tortello +6
A deep understanding of the character of superconductivity in the recently discovered Fe-based oxypnictides ReFeAsO1-xFx (Re = rare-earth) necessarily requires the determination of…
Coexistence of two order parameters and a pseudogaplike feature in the iron-based superconductor LaFeAsO_(1-x)F_x
R. S. Gonnelli, D. Daghero, M. Tortello +4
The nature and value of the order parameters (OPs) in the superconducting Fe-based oxypnictides REFeAsO_(1-x)F_x (RE = rare earth) are a matter of intense debate, also connected to…
Far-infrared signature of the superconducting gap in intercalated graphite CaC6
U. Nagel, D. Huvonen, E. Joon +3
Terahertz reflectance spectra of the Ca-intercalated graphite CaC6 reveal a superconducting gap below 11K. The gap signature lacks a sharp onset to full reflectivity at 2Delta, but…
Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy
R. S. Gonnelli, D. Daghero, D. Delaude +8
We present the first results of directional point-contact spectroscopy in high quality CaC6 samples both along the ab plane and in the c-axis direction. The superconducting order p…
Specific Heat of the Ca-Intercalated Graphite Superconductor CaC
J. S. Kim, R. K. Kremer, L. Boeri +1
The superconducting state of Ca-intercalated graphite CaC6 has been investigated by specific heat measurements. The characteristic anomaly at the superconducting transition (Tc = 1…
Implications of Tc variation in UBe13 for a possible Fulde-Ferrell-Larkin-Ovchinnikov phase
H. A. Radovan, R. J. Zieve, J. S. Kim +1
We measure the heat capacity of UBe13 with an unusually low Tc for a polycrystal. We find an upturn in the upper critical field Hc2(T) below about Tc/2, much as for higher-Tc sampl…
Heavy-ion irradiation of UBe13 superconductors
H. A. Radovan, E. Behne, R. J. Zieve +4
We irradiate the heavy fermion superconductors (U,Th)Be_13 with high-energy heavy ions. Damage from the ions affects both heat capacity and magnetization measurements, although muc…
Unusual T_c variation with hole concentration in Bi_2Sr_{2-x}La_xCuO_{6+δ}
Mu-Yong Choi, J. S. Kim
We have investigated the variation with the hole concentration in the La-doped Bi 2201 system, BiSrLaCuO. It is found that the Bi 2201 system does…