Tuning the Phase Separation, Charge Ordering, and Electronic Transport in Electron‐Doped Manganite Films by Piezo‐Strain and Magnetic Field

Abstract The macroscopic physical properties and functionalities of strongly correlated complex oxides usually originate from and depend sensitively on microscopic interactions, which can be controlled by an external stimulus. Here, in electron‐doped La_0.85Hf_0.15MnO₃/Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ multiferroic heterostructure, the role of phase separation in manipulating charge ordering and electronic transport by piezo‐strain and magnetic field is determined. The electric‐field‐induced lateral compressive piezo‐strain suppresses the charge‐ordering transition temperature and decreases the film resistance with a giant gauge factor of 27 368, due to the enhancement of the double‐exchange interaction between the Mn³⁺–Mn²⁺ ions and the suppression of the electron‐phonon coupling stemming from the Jahn‐Teller deformation. Moreover, the magnetic field can weaken the piezo‐resistance effect by 342 times. This result, together with elastically controlled magnetoresistance effect, demonstrates intimate correlation between the piezo‐strain‐induced and magnetic‐field‐induced effects by adjusting phase separation tendency. The findings indicate the importance of phase separation in multi‐field quantum control of electron‐doped perovskite manganites.