Strain effect on the magnetism of CaMnO3

A. LOPEZ PEDROSO; S. CARREIRA; J. BRIATICO; L.B . STEREN

Conferencia; 9th Joint European Magnetic Symposia; 2018

Bulk CaMnO3(CMO) has an orthorhombic crystalline structure and is weak ferromagnetic belowTN ≈120K. This structure can be described, in the pseudocubic approximation, with a ac≈3.73Ålattice parameter. Ab-initio calculations have recently shown that the magnetic behavior ofCMO depends on surface conditions. In fact, Keshavarz et al [1] demonstrated that the Mnatoms at the surface and the sub-surface of the compound are very sensitive to structuralchanges, giving rise to ferromagnetic couplings.With the aim of studying the effect of substrate-induced strains onto the magnetic behavior ofCMO thin films we grew a series of samples by pulse laser deposition onto SrTiO3(001) singlecrystallinesubstrates. In order to examine the effect of strains onto the magnetism of CMO, thefilm?s thickness was varied from 3nm to 30nm.Structural and magnetic measurements were performed to characterize the sample?sproperties. The film?s structure, analyzed by X-ray diffraction measurements, reveals a stronglytextured growth along the (0k0) direction and remarkable substrate-induced strains effects onthe lattice parameters of the compound. The mismatch between bulk CMO ac≈3.73Å andSrTiO3 aSTO≈3.905Å lattice parameters is 4.48%. The magnetic characterization wasperformed with a SQUID magnetometer. Magnetization loops, measured at 10K show that themagnetization of the samples is strongly enhanced for the thinner films.[1]Keshavarz et al, Phys. Rev. B 95, 115120 (2017)