Atomic structure, magnetism, and transport properties of damaged La0.67Ca0.33MnO3−δ processed via high-energy ball milling

A La0.67Ca0.33MnO3−δ alloy was produced via a low-temperature solid state reaction in a high-energy ball mill. The milled alloy is found to exhibit the paramagnetic-to-ferromagnetic (P–F) transition at 150 K. However, the widely reported insulator-to-metal (I–M) transition that usually accompanies the P–F transition is totally suppressed. Anneals at 500–1000 °C in air (t=8 h) are found to lower the resistivity but not restore the I–M transition. The suppression of the I–M transition is attributed to anion defects in the structure that have not been annihilated during heat treatments. Extended x-ray absorption fine structure is employed to track the evolution of the atomic structure around the Mn cations at various stages of processing.