Normal and Superconducting State Properties of Doped CePt3Si

• Published in: Journal of low temperature physics 2007-05, Vol.147 (3-4), p.135-146
• Main Authors: Kim, J. S., Mixson, D. J., Burnette, D. J., Stewart, G. R.
• Format: Article
• Language: English
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-007-9304-2

We report on X-ray powder diffraction, magnetic susceptibility, electrical resistivity, and specific heat measurements on samples of Ce1-xLaxPt3Si and CePt3Si1+delta in order to better understand this unusual heavy Fermion superconductor's normal and superconducting state properties. By suppressing the antiferromagnetic transition, TN = 2.2 K, using La-doping on the Ce-site in CePt3Si, we find that in Ce1-xLaxPt3Si, x > = 0.8, rho, chi, and C/T show non-Fermi liquid temperature dependences. C/T ~ T with alpha ~ 1 for the temperature range of 0.3-3 K while low-temperature (2-20 K) susceptibility data follow 1/chi-1/chi0 = aT behavior with eta = 0.36. In addition, chi and C/T exhibit single-ion behavior in this composition range (x > = 0.8), i.e. the measured values expressed per Ce-mole are independent of x. Via doping the Si-site with a small excess-2-4-of Si, we present specific heat data for the bulk superconducting transition at Tc ~ 0.8 K showing that this excess sharpens the transition, obviating the need for annealing. Measurements of the X-ray diffraction patterns, rho, chi, and C/T of these CePt3Si1+delta samples, when compared to similar measurements on annealed CePt3Si samples, indicate that the microscopic mechanism for the strengthening and sharpening of DeltaC(Tc) with Si-excess may be similar to that responsible in the annealed material.