Phase transition in the normal state of the non-centrosymmetric superconductor Mo₃Al₂C

We found a phase transition in the normal state of superconducting carbide, Mo₃Al₂C by nuclear magnetic resonance (NMR) measurement. At ~130 K the sharp central NMR line broadens and has additional broad components at the foot. In addition, the Knight shift and the spin-lattice relaxation rate exhibit a significant decrease, suggesting the reduction in the conduction electron density. From these results, Mo₃Al₂C undergoes the phase transition which can be understood as the charge-density wave ordering. The decrease in 1/T₁ confirms the superconductivity appears in the partially quenched Fermi surface.