Magnetic ordering in Ce substituted zirconite-YCrO4 nanostructures: focus on tunable energy bandgap and local-atomic environment

Abstract

Abstract This study presents a comprehensive investigation of the structural, magnetic, electronic, and optical spectroscopic properties of tetragonal Zirconite Y1−x Ce x CrO4 polycrystals that were synthesized at various temperature ranges. The YCrO4 phase in its pristine state demonstrates ferromagnetic (FM) ordering, characterized by a Curie temperature, T C ∼ 9.3 K. Nevertheless, the introduction of magnetic Ce3+ in place of Y3+ ions results in a reduction of the T C and the appearance of a weak antiferromagnetic (AFM) behaviour, as indicated by the presence of a negative Curie–Weiss temperature (−10 K ≲ θ CW ≲ −30 K). It is observed that the introduction of moderate levels of Ce substitution leads to a significant increase in thermal irreversibility in the magnetization difference between field-cooled and zero-field-cooled states ΔM (M FC − M ZFC). This phenomenon indicates the substantial influence of magneto-crystalline anisotropy that exists within the system. Field-dependent magnetization data exhibits higher saturation magnetization values (M S ≳ (2.7 to 4.4) × 103 emu mole−1) and higher magneto-crystalline anisotropy (K 1 ∼ 2.18 to 3.41 J m−3) for the dilute dispersion of Ce (x ≤ 0.05). Local atomic environment probed by the electron spin resonance clearly indicates the presence of hyperfine splitting of Cr5+ spectra having a single d-electron ( t 2 g 1 e g 0 ) with orbital configuration bearing the possible doublet: F = 1 , 2 I = 3 2 J = 1 2 . On the other hand, the rare-earth Ce3+ spectra show hyperfine-doublets as 7 2 and 9 2 . Finally, the energy band-gap (E g = 2.14 to 2.38 eV, for x ∼ 0 to 0.1) determined from the diffuse reflectance spectroscopy reveals the emergence of intermediate localized states upon substitution of Ce3+.