Magnetic and transport properties of PrRhSi3
We have investigated the magnetic and transport properties of a noncentrosymmetric compound PrRhSi3 by dc magnetic susceptibility χ(T), isothermal magnetization M(H), thermoremanent magnetization M(t), specific heat Cp(T), electrical resistivity ρ(T,H) and muon spin relaxation (μSR) measurements. At low fields χ(T) shows two anomalies near 15 and 7 K with an irreversibility between ZFC and FC data below 15 K. In contrast, no anomaly is observed in Cp(T) or ρ(T) data. M(H) data at 2 K exhibit very sharp increase below 0.5 T and a weak hysteresis. M(t) exhibits very slow relaxation, typical for a spin-glass system. Even though the absence of any anomaly in Cp(T) is consistent with the spin-glass type behavior, there is no obvious origin of spin-glass behavior in this structurally well ordered compound. The crystal electric field (CEF) analysis of Cp(T) data indicates a CEF-split singlet ground state lying below a doublet at 81(1) K and a quasi-triplet at 152(2) K. The ρ(T) data indicate a metallic behavior, and ρ(H) exhibits a very high positive magnetoresistance, as high as ∼300% in 9 T at 2 K. No long range magnetic order or spin-glass behavior was detected in a μSR experiment down to 1.2 K.
Unique Magnetic Phases in an Antiferromagnet CeCoGe3
We report on the magnetic properties of CeCoGe 3 by measuring the electrical resistivity, magnetic susceptibility, magnetization and specific heat, together with the magnetic properties of a reference compound LaCoGe 3 . The measurements were performed on a single crystal grown from a high-temperature solution using a third element, bismuth as flux. From the magnetic susceptibility and magnetization measurements, CeCoGe 3 is an antiferromagnet with a Neel temperature T N1 =21 K and undergoes two successive transitions T N2 =12 K and T N3 =8 K. The magnetization for H ∥[001] indicated a metamagnetic transition with three steps. We constructed a magnetic phase diagram from the magnetization measurements, which is very complex and is roughly similar to the previous result performed on a polycrystalline grain-aligned sample.
Nonunitary Spin-Triplet Superconductivity in UPt3 : Evidence from 195Pt Knight Shift Study
1Department of Physical Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 2Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan 3Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan 4Faculty of Engineering, Toyama Prefectural University, Toyama 939-0398, Japan (Received 4 September 1997 ) 195Pt Knight shift (KS) measurements covering the superconducting multiple phases for major field (H) orientations have been carried out on the high-quality single crystal UPt 3. For H . 5 kOe, the KS does not change below the superconducting transition temperature Tc down to 28 mK, regardless of major crystal orientations, which provides evidence that the odd-parity superconductivity with the parallel spin pairing is realized. By contrast, the KSdecreasesbelow Tc for Hb k b axis and Hb , 5 kOe and forHc k c axis andHc , 2.3 kOe, whereas the KS for Ha k a axis isT independent acrossTc down to Ha , 1.764 kOe. These novel findings entitle UPt 3 as the first spin-triplet oddparity superconductor including a nonunitarypairing characterized by the two-component d vector like db 1 idc at low T and lowH. [S0031-9007(98)05803-7]