Nuclear spin-lattice relaxation rate in noncentrosymmetric   superconductor Y$_2$C$_3$
  For a noncentrosymmetric superconductor such as Y$_2$C$_3$, we consider a parity-mixing model composed of spin-singlet s-wave and spin-triplet f-wave pairing components.   The $d$-vector in f-wave state is chosen to be parallel to the Dresselhaus asymmetric spin-orbit coupling vector.   It is found that, the quasiparticle excitation spectrum exhibits distinct nodal structure as a consequence of parity-mixing. Our calculation predict anomalous noninteger power laws for low-temperature nuclear spin-lattice relaxation rate $T_{1}^{-1}$.   We demonstrate particularly that such a model can qualitatively account for the existing experimental results of the temperature dependence of $T_{1}^{-1}$ in Y$_2$C$_3$. 
Chongju Chen and Biao Jin
cond-mat.supr-con