Effect of Ce substitution on the local magnetic ordering and phonon instabilities in antiferromagnetic DyCrO3 perovskites

A detailed crystal structure analysis, temperature and field dependence of magnetic characteristics and phonon instabilities for different compositions (0.1 <= x <= 0.5) of Dy1-xCexCrO3 solid-solutions have been reported. All the investigated compounds exhibit distorted orthorhombic crystal structure with a distortion factor of d(Oct)/d(Cell) similar to 6 x 10(-3)/3.5 ppm (for x similar to 0.2) for Pbnm space group that follows Vegard's law. The bonds between apical oxygen atoms (O-A1) and Cr atoms stand more rigidly in comparison with the basal oxygen atoms (O-B1/O-B2) resulting the octahedral distortion and thereby causing the changes in phonon modes. The CrO6 octahedral tilt angle theta rotates with respect to the Miller pseudocubic axis [101] which varies from 10.36 degrees (x = 0.1) to 12.25 degrees (x = 0.5) and significantly influences the A(g)(5) phonon stability by 3% for a change in A-site mean radius from 1.095 angstrom to 1.141 angstrom for x = 0.1 and 0.5, respectively. From the magnetization measurements we find that these series of compositions exhibit canted antiferromagnetic (AFM) ordering with Neel temperature, TN1 that increases from 151.8 K (x = 0.1) to 162 K (x = 0.5) which also manifests as a significant reduction in the magneto-crystalline anisotropy (HK similar to 2.58 kOe -> 2.07 kOe, K-1 similar to 36.47 J m(-3) -> 18.97 J m(-3)) while maintaining the stable Gamma(4)(G(x), A(y), F-z) AFM configuration. Both Dzyaloshinskii-Moriya interaction method and modified Curie-Weiss law are employed to analyse the inverse paramagnetic susceptibility, chi(-1)(T > TN1). Further, we have evaluated the symmetric (JS) and antisymmetric exchange (DAS) constants, which show progressively increasing trend (J(S) -> 10.08 K to 11.18 K and D-AS -> 1.24 K to 1.73 K) with the incorporation of Ce inside the perovskite lattice. Furthermore, the role of Ce substitution on the low-temperature spin reorientation transition (T-SR similar to 3.5 K -> 16.8 K pertaining to the Gamma(25) phase configuration) and emergence of Gamma 2(F-x,C-y,G(z);F-x(R),C-y(R)) weak-FM phase between 31 K and 45.5 K are discussed in consonance with the phonon spectra.

Automated summary

A study on the crystal structure, magnetic characteristics, and phonon instabilities of Dy1-xCexCrO3 solid-solutions reveals the significant influence of Ce doping on the crystal structure and magnetism.