W.A. Fertig

The re-entrant superconducting-normal phase boundary of the Kondo system (La, Ce)Al2☆

Abstract The re-entrant superconducting-normal phase boundary of the ( La , Ce)Al2 system is reported. The pair breaking parameter deduced from the data increases with decreasing temperature as (-ln T) between 0.1 and 3.30°K. This behaviour suggests that the Kondo temperature TK ⪅ 0.1°K. No evidence was found for a third transition temperature down to 6 m°K.

Re-entrant superconductivity and magnetic ordering in the pseudoternary system (Er1−xHox)Rh4B4

Abstract The boundaries between the normal paramagnetic, superconducting, and normal magnetically-ordered phases in the tetragonal pseudo-ternary rare earth system (Er1−xHox)Rh4B4 have been established by means of ac susceptibility measurements to temperatures as low as 0.07 K.

Superconducting and magnetic properties of ErRh/sub 4/B/sub 4/

The thermal expansion, magnetization, magnetostriction, and ac electrical resistance of the compound ErRh4B4 have been measured at low temperatures. The influence of magnetic fields on the superconducting and magnetic properties of this compound is emphasized, and the qualitative behavior of the upper critical field as a function of temperature has been determined from the experiments.

Coexistence of superconductivity and long-range antiferromagnetic order in the compound ErxMo6Se8

Abstract Low temperature specific heat and magnetic susceptibility measurements indicate that superconductivity and long-range antiferromagnetic order coexist in the compound Er x Mo 6 Se 8 ( x = 1.0 and 1.2).

Superconducting—normal phase boundaries of (La, Th)Ce systems

Abstract The dependence of the superconducting transition temperature Tc on Ce impurity concentration n is reported for various ( La, Th )Ce systems. These results document for the first time the evolution of the superconducting— normal phase boundary (Tc vs n curve) as an impurity undergoes magnetic- nonmagnetic transition which for Ce impurities in ( La, Th )Ce systems proceeds with increasing Th concentration. Observed for only the second time, re-entrant Tc vs n curves are reported for two La-rich La, Th host compositions.

Observation of a Kondo effect for a dilute alloy containing Sm impurities

Abstract Measurements of the depressions of the superconducting transition temperature T c with Sm impurity concentration and the specific heat jump at T c as a function of T c , and the temperature dependences of the normal state specific heat and magnetic susceptibility are reported for the matrix impurity system ( La Sm)Sn 3 . The results constitute the first definitive evidence of a Kondo effect for a dilute alloy containing Sm impurities.

Superconductivity of transition metal sulfides, selenides, and phosphides with the NaCl structure

The superconducting properties of transition metal sulfides, selenides, and phosphides having the cubic NaCl structure are described. Binary compounds found to be superconducting are ThS, ScSe, ThSe, HfP, and ThP. More detailed information about the known superconductors Zr1−xS, LuS, Sc1−xS, YS, and ZrP is presented. Transition temperature was established as a function of composition for Zr-S, Sc-S, and Y-S NaCl-structure systems. Superconductivity at high pressure was determined in several systems. Some low-temperature specific heat capacity results, room-temperature magnetic susceptibility, and electrical resistance measurements between 2 K and room temperature are reported. Some information is presented about the rhombohedrally distorted compounds ZrSe and HfS. Results of NaCl-structure solid solution (metal replacement) synthesis (including superconductivity data) are reported for (Zr, Sc)-S, (Zr, Y)-S, (Zr, Ti)-S, (Zr, Hf)-S, (La, Y)-S and (Y, Th)-S. We find that superconductivity occurs generally in these materials, and that these compounds have much in common with the better known NaCl defect structure carbides and nitrides.

Superconducting ion beam sputtered chromium metal thin films

Abstract Ion beam deposited Cr thin films have been found to be superconducting at temperatures of up to 1.52 K. Transition temperatures were dependent on the ion specie used for film deposition with lower T c s obtained for smaller atomic radius gases.

PRESSURE DEPENDENCE OF THE SUPERCONDUCTING TRANSITION TEMPERATURE OF THORIUM.

Abstract The pressure dependence of the superconducting transition temperature of thorium metal to 160 kbar is reported.

Kondo Anomalies due to Rare Earth Impurity Ions

Rare earth (RE) ions are capable of producing “Kondo-like” anomalies in the physical properties of both concentrated and dilute RE metallic systems which are qualitatively similar. These temperature dependent anomalies scale with a characteristic temperature T0, above which the RE metallic system behaves magnetically and below which it behaves nonmagnetically. The physical properties in which Kondo-like anomalies are found include the electrical resistivity, magnetic susceptibility, thermoelectric power, specific heat, and, in systems where appropriate, superconducting properties such as the critical temperature Tc and the jump in specific heat which occurs at Tc. The anomalies can be viewed as originating from admixture of the localized 4f electron states with the extended states of the conduction band, which can be traced to the unstable valence of certain RE ions.