Abstract
We investigated the relative importance of removing the Mn3+ Jahn-Teller distortion in driving ferromagnetism in LaMn1-xScxO3 combining x-ray powder diffraction and x-ray absorption spectroscopy at the Mn and Sc K-edges. By increasing the Sc content, the orthorhombic distortion of the Pbnm cell in LaMnO3 decreases but the unit-cell remains slightly distorted in LaScO3. Besides, the nearly tetragonal-distorted MO6 in LaMnO3 continuously evolves into a nearly regular one in LaScO3. On the other hand, x-ray absorption spectra show that the MnO6 octahedron remains Jahn-Teller distorted and the ScO6 octahedron is nearly regular along the whole series. Moreover, the ordering of the Mn3+ Jahn-Teller distortion is not disrupted in the ab plane for any Sc concentration. This contrasts with the Ga- substituted compounds, where a regular MnO6 is found for x>0.5. However, both LaMn0.5Sc0.5O3 and LaMn0.5Ga0.5O3 show ferromagnetic behavior independently of the presence (or not) of Jahn-Teller distorted Mn3+. Thus, our results point to the Mn-sublattice dilution as the main effect in driving ferromagnetism in these manganites over local structure effects previously proposed by the spin flipping or the vibronic superexchange models.
Highlights
Doped manganites have been extensively studied owing to their colossal magnetoresistance property and its potential applications to magnetic devices
It is known that the A-type AFM orbitally ordered state of LaMnO3 is easy destroyed to give way to ferromagnetism (FM) by introducing various cations on the Mn site [2,3,4,5]
We have studied the crystallographic structure by x-ray powder diffraction (XRD) and the local structure by x-ray absorption spectroscopy (XAS) at the Mn and Sc K-edges in the LaMn1-xScxO3 series in order to clarify the importance of removing the Jahn-Teller distortion in driving the FM behavior
Summary
Doped manganites have been extensively studied owing to their colossal magnetoresistance property and its potential applications to magnetic devices. Both models assume that the change from A-type AFM to FM ordering is originated by the orbital direction adopted by the Mn3+ ion and it is similar for Ga and Sc non-magnetic substitutions, so the atomic eg orbital would be perturbed in the same way for the two series.
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