NMR in local fields at 139La nuclei in ferromagnetic manganites with a metal-semiconductor transition
Gubkin M. K., Zalesskii A. V., Krivenko V. G., Perekalina T. M., Khimich T. A., Chubarenko V. A.
A spin-echo method has been used to measure the temperature dependence of the local magnetic fields at LWLa nuclei in several manganites in the region of ferromagnetism and a metallic conductivity. The observed fields, on the order of 30 kOe, depend only weakly on the temperature. They remain high right up to the Curie point. It is suggested that the local fields at the B4La nuclei stem from spin-polarized current carriers which mediate a double exchange. An explanation is proposed for the unusual temperature dependence of the local field and that of the amplitude of the spin echo. The explanation is based on the argument that the samples are of a magnetically multiphase nature near the Curie point.