Charge transport studies on chemically grown manganite based heterostructures

Abstract

In this communication, we have successfully fabricated mixed valent La0.7Ca0.3MnO3 (LCMO) manganite based (i) ZnO/LCMO/LAO and (ii) LMO/LCMO/LAO (LMO: LaMnO3–d thin layer; LAO: LaAlO3 substrate) thin film heterostructures using chemical solution deposition (CSD) method. 100 nm LCMO layer was initially grown on single crystalline (100) LAO substrate followed by the growth of 50 nm ZnO and LMO layers separately on the two different heterostructures. In the present study, upper layers of ZnO and LMO were intentionally prepared at 700 °C for 12 h under air environment, thereby some naturally created oxygen vacancies are expected to be present in their lattices. Presence of oxygen vacancies makes ZnO and LMO layers as n–type oxides in the heterostructures. Temperature dependent current–voltage (I–V) characteristics and interface resistivity (under different applied electric fields across interface only) were carried out to understand their charge transport behavior. A strong effect of electric field on the resistivity behavior has been observed due to a reasonable electrically polarizable (active) nature of ZnO and LMO thin layers. Zener double exchange (ZDE) polynomial law has been employed to understand various scattering processes as source of resistivity across, both, ZnO/LCMO and LMO/LCMO interfaces. Transport properties and charge conduction mechanisms have been discussed and compared for both the interfaces in the context of interface state and barrier between electrically active layer and LCMO film. Also, power consumption criteria have been discussed in detail for the presently studied heterostructures for their practical device applications such as field effect devices, memory devices, read–write head devices or any other spintronic devices.