Effect of A-Site Cation Ordering on the Electrical and Magnetic Properties of Manganite Films

(111)-oriented [(SrMnO3)(1)/(LaMnO3)(2)](n) superlattices with artificial A-site cation ordering with respect to the compositionally equivalent La2/3Sr1/3MnO3 films with a random distribution of the A-site dopants are fabricated. It is found that the ferromagnetism and electrical transport properties of La2/3Sr1/3MnO3 films are primarily independent of the degree of A-site cation ordering, as evidenced by their identical critical temperatures of phase transition. These results may reveal the spontaneous nature of the electronic phase separation, which is key to the colossal magnetoresistance effect in manganites. In contrast, compared to the La2/3Sr1/3MnO3 films, the A-site ordered (111) superlattices have a tendency to preserve oxygen vacancies inside, making them extremely difficult to be compensated by the post-annealing process.