Control of magnetism by crystal chemistry in T '-phase R2Cu1-xPdxO4 (R = Nd, Sm, Eu, Gd; 0 <= x <= 0.2)

Journal article

Polycrystalline samples of the T′-phases R2Cu1-xPdxO4 (R=Nd, Sm, Eu, Gd; 0≤x≤0.2) have been characterized by x-ray powder diffraction (XRPD) and magnetometry. Doping with diamagnetic Pd induces orthorhombic symmetry and hence weak ferromagnetism in the Sm (x≥0.1) and Eu (x≥0.05) phases, which are antiferromagnetic for x=0.0. The structural distortion is too subtle to be observed directly by XRPD, but it is shown that the derivative ∂(c/a)/∂x (positive for orthorhombic, ferromagnetic phases and negative for the tetragonal phases) can be used as a diagnostic. The dopant concentration necessary to induce the transition is determined by the ratio of ionic radii rR/rM, where rM is the mean radius of the four coordinate cation (Pd/Cu). Samples having rR/rM<1.87 are weak ferromagnets; Nd3+ is too large for this condition to be satisfied in the composition range studied, whereas Gd3+ is too small to stabilize tetragonal T′-phases. There is evidence for re-entrant spin-glass behavior in Pd-free Eu2CuO4.

Authors: Vente, J; Battle, P

• Publication status: Published
• Journal: Physical Review B
• Volume: 58
• Issue: 5
• Pages: 2699-2707
• Publication date: 1998-08-01
• DOI: 10.1103/PhysRevB.58.2699
• EISSN: 1095-3795
• ISSN: 1098-0121
• Language: English