Competing exchanges and spin-phonon coupling in Eu1-xRxMnO3 (R=Y,Lu)

TL;DR

This study investigates how doping EuMnO3 with Y or Lu affects its phase diagrams and physical properties, highlighting the importance of the tolerance factor and spin-phonon coupling in understanding phase stability.

Contribution

It demonstrates that the tolerance factor effectively normalizes phase boundaries across different dopants and reveals the role of spin-phonon coupling in phase stabilization.

Findings

Tolerance factor normalizes phase boundaries for Y and Lu doping.

Spin-phonon coupling stabilizes the AFM4 phase in Lu-doped EuMnO3.

Differences in low-temperature phases are not fully explained by the tolerance factor alone.

Abstract

This work is focused on the phase diagrams and physical properties of Y-doped and Lu-doped EuMnO3. The differences in the corresponding phase boundaries in the (x,T) phase diagram could be overcome by considering a scaling of the Y3+ and Lu3+ concentrations to the tolerance factor. This outcome evidences that the tolerance factor is in fact a more reliable representative of the lattice deformation induced by doping. The normalization of the phase boundaries using the tolerance factor corroborates previous theoretical outcomes regarding the key role of competitive FM and AFM exchanges in determining the phase diagrams of manganite perovskites. Though, significant differences in the nature and number of phases at low temperatures and concentrations could not be explained by just considering the normalization to the tolerance factor. The vertical phase boundary observed just for Lu-doped EuMnO3, close to 10%Lu, is understood considering a low temperature Peierls-type spin-phonon coupling, which stabilizes the AFM4 phase in Lu-doped EuMnO3.