Influence of La and Mn vacancies on the electronic and magnetic properties ofLaMnO3thin films grown by pulsed laser deposition

Abstract

With pulsed laser deposition we have grown c-axis oriented thin films of the nominal composition LaMnO 3 (LMO) on LSAT(001) substrates. We find that, depending on the oxygen background pressure during growth, the LMO films contain sizeable amounts of La and/or Mn vacancies that strongly influence their electronic and magnetic properties. Specifically, we show that the Mn/La ratio can be systematically varied from 0.92 at 0.11 mbar to 1.09 at 0.30 mbar of oxygen.These cationic vacancies lead to markedly different disorder effects that become most pronounced once the samples are fully oxygenated and thus strongly hole doped. All as-grown and thus slightly oxygen deficient LMO films are ferromagnetic insulators with saturation moments in excess of 2.5  Bper Mn ion, their transport and optical properties can be understood in terms of trapped ferromagnetic polarons. Upon oxygen annealing, the most La-deficient films develop a metallic response with an 39

X-ray absorption study of the ferromagnetic Cu moment at theYBa2Cu3O7/La2/3Ca1Sen1, Perret2, Alberca3 et al. 2016Phys. Rev. B213260View full textAdd to dashboardCite

“…The development below T Curie of such a MIR band is well known from bulk manganites that are in the less hole-doped part of the phase diagram close to the insulating FM (I-FM) phase where the charge carriers start to form FM polarons [39]. The signatures of this MIR band are also seen in a corresponding ML with LaMnO 3+δ (LMO) layers that are known to be in the I-FM state [14,40] [see Fig. 7(b)].…”

Metal Oxide Nanocomposites: A Perspective from Strain, Defect, and Interface

“…For instance, ion liquid gating has been used to tune the functional properties via controlling oxygen ion migration in a variety of oxide thin films . Both the formation of cation vacancies and the change of the valence state have been observed in bulk and thin film LaMnO 3 …”

Engineering Transport in Manganites by Tuning Local Nonstoichiometry in Grain Boundaries

“…To understand the correlation between the superior performance of dense LSM layers and their local structure, we first prepared Mn‐deficient polycrystalline films by means of pulsed laser deposition (PLD) on top of yttria stabilized zirconia (YSZ)‐based substrates (YSZ/Si 3 N 4 /SiO 2 /Si), using a proper selection of deposition parameters . LSM films showed a fully dense polycrystalline structure, with well‐defined nanometric columnar grains of tens of nanometers in diameter ( Figure a,b) and a Mn/(La + Sr) ratio of B / A = 0.85 ± 0.02, as measured by wavelength‐dispersive spectroscopy (WDS).…”