Magnetic properties of pseudomorphic epitaxial films of Pr_{0.7}Ca_{0.3}MnO_3 under different biaxial tensile stresses

TL;DR

This study investigates how biaxial tensile stresses influence the magnetic properties of ultrathin Pr0.7Ca0.3MnO3 films grown on different SrTiO3 substrates, revealing strain-dependent magnetic behaviors and phase coexistence.

Contribution

It demonstrates the impact of epitaxial strain on magnetic phases in ultrathin manganite films, highlighting the role of substrate-induced crystallographic constraints.

Findings

(001) SrTiO3 films show cluster-glass behavior.

(110) SrTiO3 films exhibit robust ferromagnetism.

Strain influences orbital hybridization and magnetic phase stability.

Abstract

In order to analyse the effect of strain on the magnetic properties of narrow-band manganites, the temperature and field dependent susceptibilities of about 8.5 nm thick epitaxial Pr0.7Ca0.3MnO3 films, respectively grown on (001) and (110) SrTiO3 substrates, have been compared. For ultrathin samples grown on (001) SrTiO3, a bulk-like cluster-glass magnetic behaviour is found, indicative of the possible coexistence of antiferromagnetic and ferromagnetic phases. On the contrary, ultrathin films grown on (110) substrates show a robust ferromagnetism, with a strong spontaneous magnetization of about 3.4 mB /Mn atom along the easy axis. On the base of high resolution reciprocal space mapping analyses performed by x-ray diffraction, the different behaviours are discussed in terms of the crystallographic constraints imposed by the epitaxy of Pr0.7Ca0.3MnO3 on SrTiO3. We suggest that for growth on (110) SrTiO3, the tensile strain on the film c-axis, lying within the substrate plane, favours the ferromagnetic phase, possibly by allowing a mixed occupancy and hybridization of both in-plane and out-of-plane eg orbitals. Our data allow to shed some physics of inhomogeneous states in manganites and on the nature of their ferromagnetic insulating state.