Effects of La non-magnetic impurities on the spin resonance of CeCoIn${}_5$

Abstract

The influence of La non magnetic impurities on the spin dynamics of CeCoIn${}_5$ was studied by inelastic neutron scattering. In La-substituted systems, the spin resonance peak (observed at ${\Omega }_{res}=0.55meV$ in the pure system) is shifted to lower energies but the ratio ${\Omega }_{res}/k_B{T}_c$ remains unchanged. The excitation broadens till it reaches 0.3 meV equal to the value of the quasi-elastic signal in the normal state. The evolution of La substitution is compared with the evolution of the magnetic resonance in Ni and Zn substituted YBa${}_2$Cu${}_3$O${}_7$.

4 pages, 5 figures