Crystal and magnetic structure of (La0.70Ca0.30)(CryMn1-y)O3: a neutron powder diffraction study

TL;DR

This study investigates the crystal and magnetic structures of (La0.70Ca0.30)(CryMn1-y)O3 for various y values using neutron powder diffraction, revealing different magnetic orders and impurity effects at low temperatures.

Contribution

The paper provides detailed neutron diffraction analysis of magnetic structures in (La0.70Ca0.30)(CryMn1-y)O3 for y=0.70, 0.50, 0.15, highlighting the evolution of magnetic order with composition.

Findings

Cr-rich sample exhibits G-type antiferromagnetic order.

Mn-rich sample shows ferromagnetic order of Mn spins.

Cr ions act as magnetic impurities in mixed compositions.

Abstract

The crystal and magnetic structure of (La0.70Ca0.30)(CryMn1-y)O3 for y = 0.70, 0.50 and 0.15 has been investigated using neutron powder diffraction. The three samples crystallize in the Pnma space group at both 290 K and 5 K and exhibit different magnetic structures at low temperature. In (La0.70Ca0.30)(Cr0.70Mn0.30)O3, antiferromagnetic order with a propagation vector k = 0 sets in. The magnetic structure is Gx, i.e. of the G-type with spins parallel to the a-axis. On the basis of our Rietveld refinement and the available magnetisation data, we speculate that only Cr3+ spins order, whereas Mn4+ act as a random magnetic impurity. In (La0.70Ca0.30)(Cr0.50Mn0.50)O3 the spin order is still of type Gx, although the net magnetic moment is smaller. No evidence for magnetic order of the Mn ions is observed. Finally, in (La0.70Ca0.30)(Cr0.15Mn0.85)O3 a ferromagnetic ordering of the Mn spins takes place, whereas the Cr3+ ions act as random magnetic impurities with randomly oriented spins.