Insulator-metal phase transition of Pr_0.6Ca _0.4MnO₃ studied by x-ray absorption spectroscopy in pulsed magnetic fields

Evolution of the Mn K-edge x-ray absorption near edge structure (XANES) in Pr_0.6Ca_0.4MnO₃ at pulsed magnetic fields has been investigated. A small enhancement of XANES spectra is detected across the magnetic-field-induced transition from the charge-and orbital-ordered (COO) insulator to ferromagnetic metal at 20K. It is found that the magnetic-field dependence of the enhancement shows clear hysteresis, as seen in the magnetization with metamagnetic transition, suggesting a significant correlation between the change in the XANES and the field-induced collapse of the COO state. The enhancement of the absorption can be explained by an increase of the 4p density of states due to a reduction of hybridization between the 4p state of the central Mn ion with the core hole and the neighboring Mn 3d state. Local structural change around Mn ions is expected to modify the strength of the hybridization.