Electron Spin Resonance Study on the Charge-Ordered State in Pr_<0.65>Ca_<0.35>MnO_3

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The distorted perovskite manganese, Pr_<0.65>Ca_<0.35>MnO_3 was studied on the magnetic behavior of the electron spin of 3d-t_<2g> and 3d-e_g on Mn^<3+> and Mn^<4+> ionic sites. X-band electron spin resonance (ESR) and x-ray powder diffraction were performed at temperature range from 300K down to 10K. We observed the onset of the charge-ordered state at T_<CO>∿215K thanks to temperature dependence of lattice constants, the antiferromagnetic transition at T_<AF>∿180K based on the ESR linewidth ΔH_<p-p>, and the canted antiferromagnetic transition at T_<CAF>∿125K from both the appearance of the spontaneous d. c. magnetization and an abrupt increase of the ΔH_<p-p>. Below 90K, there exists a remarkable decomposition of the unique ESR profile, which suggests the existence of at least a couple of modes as a result of disorder in the antiferromagnetic order below 180K. These observations are responsible for an irreversible hysteresis in d. c. magnetization between the field cooling and zero-field cooling process below T_<CAF>∿125K. They provide a part of evidence on the existence of the spin-glass state as has been proposed by Yoshizawa et al [Phys. Rev. B52,1689-1692 (1996)].
弓削商船高等専門学校の論文
2001-02-28