Inelastic Neutron Scattering Studies to Understand Magnetism of Ca3CuMnO6

Quasi 1-D spin-chain compounds of the type A3MXO6 are among the low dimensional systems in which quantum mechanical wave function confined in one spatial dimension, have been gaining considerable attention in recent times due to interesting physical phenomena seen among this family members. The stoichiometric Ca3CuMnO6 compound (T$_N1$ = 5.5K; T$_N2$ = 3.6K), is unique among this class since, so far it is the only reported system in a triclinic structure. The structure forms in a triclinic structure, space group P-1. Interestingly, the magnetic measurements and magnetic structure of the off-stoichiometric, isostructural compound, Ca3Cu0.93Mn1.07O6, reveal ferrimagnetism at a significantly enhanced temperature (T$_N1$ = 23 K). In addition, off-stoichiometric composition exhibits another anomaly around T$_N2$ = 100 K, as observed in ac susceptibility and dielectric measurements. The magnetic moment observed from magnetization, μ_eff = 3.54μB per formula unit is close to calculated free ion moment for Cu2+ = 3.55μB (J = 5/2)) and from neutron diffraction measurements) points out that Cu2+ is the only magnetic ion, whereas the contribution from Mn4+ is largely muted here. These studies have thus raised an important question about the role of stoichiometry, bond-lengths in the control over physical properties. In this context, we propose to investigate the role of Cu2+ Jahn-Teller ion in suppressing the magnetism of Mn4+ ion by using the inelastic neutron scattering method.