THE LINEAR TEMPERATURE-DEPENDENCE OF THE PARAMAGNETIC-RESONANCE LINEWIDTH IN THE MANGANATE PEROVSKITES LA0.67SR0.33MNO3 AND LA0.62BI0.05CA0.33MNO3

The temperature dependence of the static magnetic susceptibility chi(0 ) (5 to 700 K) and that of the electron paramagnetic resonance linewid th Delta H (300 to 700 K) measured at 9.25 GHz is reported for bulk po lycrystalline samples of La0.67Sr0.33MnO3 (T-c = 375 K) and La0.62Bi0. 05Ca0.33MnO3 (T-c = 238 K) with negative giant magnetoresistance. For both systems, Delta H and the product Delta H chi(0)T increase linearl y with temperature above T-c. Following the analysis of Huber and Seeh ra for CrBr3, it is argued that this linear temperature dependence of Delta H chi(0)T is most probably due to contributions from spin-phonon interaction. This result supports the recent suggestions of the impor tance of lattice effects in the magnetism of these oxides.