Enhancement of intrinsic magnetoresistance in Zn doped La0.9Sr0.1MnO3 epitaxial films

Mn-site doping is an effective avenue to tune the physical properties of manganites, but the underlying mechanism has rarely been explored in the epitaxial film systems doped with closed shell metal ions. Here, high-quality epitaxial La0.9Sr0.1Mn1-yZnyO3 (LSMZO) thin films have been successfully prepared by magnetron sputtering on LaAlO3 substrate, and the effect of Zn doping on the structural, transport and magnetic properties of the LSMZO films was investigated systematically. As Zn content increases, Curie temperature (T-C), saturation magnetization (Ms) and metal-insulator transition temperature (T-MI) are reduced, and the room-temperature resistivity is raised. Analysis on Mn3+/Mn4+ ratio shows the substitution of Mn3+ ion by Zn2+ ion reduces Mn3+/Mn4+ ratio deviating from the optimal value and thus weakening double exchange interaction. Besides that, the electron-lattice coupling stemming from the lattice distortion and Jahn-Teller QT) effect also has a significant impact. Most significantly, Zn doping induces an enhancement in the intrinsic magnetoresistance (MR) due to the enhanced magnetic disorder, and a fairly large MR of 26.4% is obtained under a low field of 0.3 Tat 210 K in the LSMZO (y = 0.20) film. Our study reveals that Zn doping at Mn site can regulate intrinsic physical properties of manganite films by modifying double exchange and electron-lattice interaction. (C) 2020 Elsevier B.V. All rights reserved.