The Effect of Cu Doping in the Nio2 Plane on the Stripe Phase in La1.67sr0.33nio4

The effect of Cu doping on the stripe-ordered state in La1.67Sr0.33NiO4 has been studied by means of electrical resistivity and magnetic measurements and transmission electron microscopy observation. The investigations reveal that Cu doping at Ni sites does not change the modulation pattern of the charge ordering, but clearly reduces the charge-ordered-transition and spin-ordering temperatures. Moreover, Cu on the NiO2 planes tends to melt the stripe lattice and reduce the charge and spin stripe correlation lengths. These effects could arise from the cooperative action of carrier mobility enhancement, strong interplay of Cu spins with the host Ni spin-lattice system, and the disordering effect of Cu dopants.