Magnetic Structure Determination of Exotic Spin-Chain Compound Ca3CuMnO6

The spin-chain systems with general formula A3MM'O6 have attracted much attention in recent years, due to their reduced dimensionality. In the present proposal we would like to understand the magnetic structure of an interesting member Ca3CuMnO6 of the spin-chain quasi-1D oxide system of the type A3MXO6 which are of current interest owing to their interesting physical properties. In our previous publications, we have shown that the stoichiometric Ca3CuMnO6 exhibits two long-range magnetic orders at T$_N1$ = 5.5 K and T$_N2$ = 3.6 K and is unique among the spin-chain quasi-1D oxide family since it is the only reported system crystallizing in a triclinic structure. The compound forms in a triclinic structure, space group P-1. In the preliminary analysis of the µSR spectra the asymmetry is reduced by 1/3rd of the usual asymmetry as soon as the system is cooled below TN1 (~ 5.5 K), indicating the strong bulk magnetic ordering in this system. This is very interesting observation in confirmation of the bulk measurement, as this sample serves as an excellent example of “order in disorder” phenomenon. The field sweep at 0.5 K for this sample shows that the internal field is very high in this system, which indicate larger moment on the Mn ion. We shall carry out neutron diffraction measurements across both magnetic ordering temperatures to unravel the temperature dependence of the magnetic structure as well as the nuclear (crystallographic) structure of this compound.