Superconductivity in the noncentrosymetric Li2Pd(3-x)AgxB with x=0.0, 0.1 and 0.3

Abstract

We studied the partial substitution of Ag in the noncentrosymetric superconducting compounds Li${}_2$Pd${}_{3-x}$Ag${}_x$B with x=0.0, 0.1 and 0.3. Magnetization, resistivity and specific heat measurements were performed in this system. From electrical measurements we obtained the critical temperature $T_c$. The upper critical field at zero temperature was determined with Werthamer-Helfand equation, ${\mu }_0{H}_{c2}^{WHH}(0)$, and ${\mu }_0{H}_{c2}^{linear}(0)$ and the coherence length, $\xi (0)$. The Value of ${\mu }_0{H}_{c2}^{linear}(0)$ and ${\mu }_0{H}_{c2}^{WHH}(0)$ is lower than the calculated paramagnetic Pauli limit suggesting that the spin-triplet pairing is weak in the system. From specific heat measurements we obtained the parameters of the normal state; the Sommerfeld coefficient, $\gamma$, the electronic density of states at the Fermi level, $N(E_F)$ and the Debye temperature, ${\theta }_D$. In the superconducting state the obtained values were; $\Delta C/\gamma T_c$, the electron phonon coupling, ${\lambda }_{e-ph}$, the superconducting energy gap, $2{\Delta }_0$, and the ratio $2{\Delta }_0/k_B{T}_c$. The electronic specific heat is well described by the BCS theory, suggesting that the energy gap is isotropic and in a strong coupling state.

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