Transport, thermal, and magnetic properties of RuSr2(Gd1.5Ce0.5)Cu2O10−δ, a magnetic superconductor

Abstract

Resistivity, thermoelectric power, heat capacity, and magnetization for samples of RuSr2(Gd1.5Ce0.5)Cu2O10−δ were investigated in the temperature range 1.8–300K with a magnetic field up to 8T. The resistive transitions to the superconducting state are found to be determined by the inhomogeneous (granular) structure, characterized by the intragranular, Tc0, and intergranular, Tcg, transition temperatures. Heat capacity, C(T), shows a jump at the superconducting transition temperature Tc0≈37.5K. A Schottky-type anomaly is found in C(T) below 20K. This low-temperature anomaly can be attributed to splitting of the ground term S7∕28 of paramagnetic Gd3+ ions by internal and external magnetic fields.

Granular superconductivity in polycrystalline ruthenocuprate RuSr2(Gd1.5Ce0.5)Cu2O10−δ: magnetoresistive and magnetization studies

“…Sample ASP1 (stored in a desiccator) has a rather broad resistive transition with resistance reaching zero at T ≈ 10 K while sample ASP2 (stored for some time in ambient air) has a much larger resistivity and a markedly broader resistive transition (of shouldered form). Here zero resistance is not reached even at T ≈ 4 K. In spite of this essential difference in resistive transitions, R(T ) curves for the two samples show the same feature (a kink) at T ≈ 34 K. This kink (or marked turn in R(T )) is determined by the transition of the intragrain material to the superconducting state at T c0 ≈ 34 K. This value of T c0 agrees well with results of heat capacity measurements for the same series of the samples [10]. In contrast to transport properties, the heat capacity temperature dependence C(T ) was found to be rather insensitive to the granular structure and oxygen annealing.…”

“…It should be mentioned that the properties of the 30 atm/O 2 annealed sample agree closely with those of the 62 atm/O 2 annealed sample described previously [10]. For that sample, temperatures T c0 ≈ 37.5 and T cg ≈ 32.8 K (derived from derivatives dR(T )/dT ) are also closely situated.…”

“…In particular, the influence of magnetic field on resistive transitions to the superconducting state in ruthenocuprates deserves further investigation. The known studies show broadening and shouldering of resistive transitions with application of magnetic field [1][2][3][5][6][7][8][9][10]. In this study, similar effects are found not only with application of a field, but also with increased measuring current as well.…”

Magnetic field dependence of the Schottky anomaly in filled skutterudites Pr1−xEuxPt4Ge12

“…Heat capacity measurements of Eu 2+ or Gd 3+ containing samples, such as (Sn 1−x Eu x )Mo 6 S 8 [14], Ba 8−x Eu x Ge 43 3 [15], and RuSr 2 (Gd 1.5 Ce 0.5 )Cu 2 O 10−δ [16], have been found to exhibit upturn in C e /T upon lowering the temperature. This upturn is due to a Schottky anomaly resulting from the splitting of the ground state octet of Eu/Gd by the internal molecular and externally applied magnetic field.…”

Short-range antiferromagnetic correlations in the superconducting state of filled skutterudite alloys Pr1−xEuxPt4Ge12

“…Furthermore, the C el vs T curve shows at least three peaks close to the antiferromagnetic transition [13]. For the purposes of the present work, it is important to mention that the heat capacity (C) measurements of Eu-or Gd-containing samples have revealed a low temperature T upturn in C/T as a function of temperature, which has been attributed to a Schottky anomaly resulting from the splitting of the ground state octet of Eu/Gd due to the internal molecular and external applied fields [14][15][16]. In contrast, the upturn in C/T vs. T data in samples containing Pr have been attributed to the crystalline electric field (CEF) splitting of the ground state of Pr [17,18].…”