Destruction of charge ordering phase in La sub(0.4)Ca sub(0.6)MnO sub(3) induced by low Cr doping

Polycrystalline samples of La sub(0.4)Ca sub(o.6)Mn sub(1-x) Cr sub(x) O sub(3) (x = 0.00, 0.02, 0.04, 0.06) were prepared by the solid state reaction method. The influence of Cr super(3+) substitution for Mn super(3+) on the magnetic property and charge ordering phase of La sub(0.4)Ca sub(0.6)MnO sub(3) was studied through the measurements of X-ray diffraction (XRD), magnetization-temperature (M-T) curves and electron spin resonance (ESR) spectra. The experimental results indicate that the mother's body of La sub(0.4)Ca sub(0.6)MnO sub(3) has very complicated magnetic structure, exhibits charge ordering phase at 258 K, and shows long-range strongly correlated charge ordering-antiferromagnetism (CO-AFM) phase from 175 to 50 K. Spin glass state appears when the temperature decreases to about 41 K. When the Cr substitution amount is x = 0.06, the charge ordering phase of the mother's body is destroyed, because the Cr super(3+) substitution for Mn super(3+) destroys the spin order of CE-type antiferromagnetism, and thus leads to the melting of charge ordering. It is verified experimentally that the strong coupling between charge order and spin order exists in the charge order system of CE-type antiferromagnetism.