Zener carriers, Jahn-Teller distortion, and colossal magnetoresistance effect in manganites

La_1-xSr_xMnO₃ (LSMO) is a well-known system with colossal magnetoresistance (CMR) effect. The competition of ferromagnetic (FM) correlation and antiferromagnetic (AFM) correlation associated with the Zener carriers is the key to understand CMR effect. In La_0.875Sr_0.125MnO₃, CMR effect mainly occurs in the paramagnetic state between Curie temperature and Jahn-Teller distortion temperature. Neutron diffuse scattering (NDS) on La_0.875Sr_0.125MnO₃ single crystals has been used to investigate the short-range magnetic ordering in the paramagnetic phase. Magnetic related rod-like shaped and sphere-like shaped NDS features are obsereved in the JT ordered state. Reconstruction of magnetic correlations by 3D delta magnetic pair distribution function (3D-ΔmPDF) indicates that rod-like shaped NDS features are related to type-A AFM correlation and sphere-like shaped NDS features are related to 3D FM correlation, confirming the coexistence of AFM and FM correlations in the JT ordered state. The 3D FM correlation is resulted from orbital mixing due to the local structure, while the type-A AFM correlation occurs from superexchange interaction as a result of JT distortion. The Zener carriers released in the vicinity of T_C under external magnetic field are responsible for the CMR effect.