We have investigated the role of Mn3+ Jahn-Teller distortion in driving ferromagnetism in the LaMn1-xScxO3 series. The replacement of Mn by Sc in LaMnO3 decreases the orthorhombic distortion of the Pbnm cell, but the unit cell remains distorted even in the LaScO3 sample. The analysis of the x-ray diffraction patterns indicates a continuous evolution from the typical Jahn-Teller distorted octahedron in LaMnO3 into a nearly regular one in LaScO3. Surprisingly, x-ray absorption spectroscopy measurements at the Mn and Sc K edges reveal the stability of both Jahn-Teller distorted MnO6 octahedron and nearly regular ScO6 octahedron along the whole Sc-substituted series. Moreover, the structure is described as a random distribution of Jahn-Teller distorted MnO6 octahedra spatially ordered as in LaMnO3 and nearly regular ScO6 octahedra. This result contrasts with the pseudocubic phase and the appearance of regular MnO6 octahedra in LaMn1-xGaxO3 for x>0.5. Thus the occurrence of Jahn-Teller distortion strongly depends on the distorted orthorhombic crystallographic structure of the matrix in which the Mn3+ atom is allocated. Besides, a ferromagnetic ground state is observed for x>0.5 in both series independently of the presence (or not) of Jahn-Teller distortions around Mn3+, which discards either the spin flipping or the vibronic superexchange models proposed for the ferromagnetism in LaMn1-xBxO3 (B=Sc or Ga).
|Titolo:||Stability of Jahn-Teller distortion ordering in LaM n1-x S cx O3|
|Data di pubblicazione:||2015|
|Citazione:||Cuartero, V., Blasco, J., Subías, G., García, J., Meneghini, C., & Aquilanti, G. (2015). Stability of Jahn-Teller distortion ordering in LaM n1-x S cx O3. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 92(12).|
|Appare nelle tipologie:||1.1 Articolo in rivista|