Comment on "Spectroscopic Evidence for Multiple Order Parameters in the Heavy Fermion Superconductor CeCoIn5"

This is a comment on recent paper by Rourke et al. titled "Spectroscopic Evidence for Multiple Order Parameters in the Heavy Fermion Superconductor CeCoIn5" (cond-mat/0409562v1 22 Sep 2004). We argue that the features observed by Rourke etal. arise from their contact not being in the ballistic limit.Comment: 4 pages with figures (pdf

Unusual Magnetotransport from two dimensional Dirac Fermions in Pd3_{3}Bi2_{2}Se2_{2}

Pd$_{3}$Bi$_{2}$Se$_{2}$ has been proposed to be topologically non-trivial in nature. However, evidence of its non-trivial behavior is still unexplored. We report the growth and magneto-transport study of Pd$_{3}$Bi$_{2}$Se$_{2}$ thin films, revealing for the first time the contribution of two-dimensional (2D) topological surface states. We observe exceptional non-saturated linear magnetoresistance which results from Dirac fermions inhabiting the lowest Landau level in the quantum limit. The transverse magnetoresistance changes from a semi-classical weak-field $B^{2}$ dependence to a high-field $B$ dependence at a critical field $B^{\star}$. It is found that $B^{\star} \propto T^2$, which is expected from the Landau level splitting of a linear energy dispersion. In addition, the magnetoconductivity shows signatures of 2D weak anti-localization (WAL). These novel magnetotransport signatures evince the presence of 2D Dirac fermions in Pd$_{3}$Bi$_{2}$Se$_{2}$ thin films.Comment: 8 pages, 6 figure

CeMnNi4: A soft ferromagnet with a high degree of transport spin polarization

In this letter we introduce a new soft ferromagnetic compound, i.e. CeMnNi4, which exhibits a large moment (~4.95mu_B/Mn) and high degree of spin polarization. The system has a ferromagnetic transition temperature of 148K. Isothermal magnetization measurements at 5K reveal that the material is a soft ferromagnet with a magnetization saturating at about 500Oe and a coercive field of < 5 Oe. We determine the transport spin polarization of this material from Point Contact Andreev Reflection measurements to be 66% thereby making this material potentially important for spintronic applications.Comment: pdf file with figures Revised Version submitted to AP