Thermodynamics Investigation on Pressure-induced Superconductor CeNiGe₃by ac Calorimetry

Abstract

We measured the heat capacity of the pressure-induced superconductor CeNiGe3 by the ac calorimetry under high pressure up to 2.4 GPa using a single crystal sample grown by the Bi-flux method. The heat capacity Cac shows the λ-type anomaly at Néel temperature TN. The pressure dependence of TN is consistent with those determined previous studies by the resistivity measurement under high pressure. At 2.1 and 2.4 GPa, the heat capacity anomaly was observed around 0.3 K. This temperature is close to the superconducting transition temperature Tsc determined by the previous resistivity measurement. Therefore, the heat capacity anomaly may be due to the superconducting transition. The value of Tsc by the present heat capacity measurement was larger than those by the resistivity measurement. This might reflect a sample dependence.

The influence of magnetic sublattice dilution on magnetic order in CeNiGe3and UNiSi2

“…The magnetic susceptibility measurements performed for the parent compounds CeNiGe 3 and YNiGe 3 confirmed the previous findings [13,14,24]. In particular, CeNiGe 3 exhibits localised antiferromagnetism below 5.5 K, while YNiGe 3 is an itinerant paramagnet with nearly temperature independent magnetic susceptibility χ(T ) (not shown here).…”

Tuning low-temperature physical properties ofCeNiGe3by magnetic field

“…lower than the previously reported value T N = 5.5 K. 10,[13][14][15] The low-temperature ͑T͒ data, measured for H ʈ a, are plotted for various applied fields in Fig. 2͑b͒.…”

“…More recently, pressure-induced superconductivity was found in electrical resistivity measurements on polycrystalline samples 13,14 and in specific heat ͑ac calorimetry͒ measurements on single crystal samples. 15 These studies indicate that the RKKY and/or Kondo interaction can be tuned by applied pressure and superconductivity can be induced in this Kondo system.…”

“…10,12 In this structure, Ce occupies a single 4j site with mm2 point symmetry. At ambient pressure and in zero field, CeNiGe 3 shows AFM order below T N = 5.5 K. 10,[13][14][15] Recent studies of polycrystalline CeNiGe 3 ͑Ref. 10͒ have inferred that the AFM order can be suppressed by external magnetic field, via metamagnetic transitions ͑MMTs͒.…”

Pressure-Induced Magnetic Transition and Disappearance of Superconductivity in CeNiGe3

“…3 (a) and (b). Note that the crossover has not been identified in previous macroscopic measurements [10] even in the calorimetric study under high pressure [19]. We speculate that a "gradual change" of the magnetic property, for example, temperature variation of the ordering vector, may obscure the corresponding anomaly in the macroscopic quantities.…”