We investigated the metal-ordered manganite system YBaMn2O6 using electron spin resonance (ESR) in the paramagnetic regime across the charge-ordering and structural phase transition at T_CO = 480 K and T_t = 520 K, respectively. All ESR parameters exhibit jump-like changes at T_t while the charge-ordering at T_CO manifests itself only as a weak and broad anomaly. Above T_t the ESR spin susceptibility is reduced with respect to the dc-susceptibility, indicating that only the t_2g-core spins of Mn ions contribute to the resonance absorption. The contribution of the e_g-spins is suppressed by the time scale of the polaronic hopping process of the e_g-electrons. The linewidth in this regime is reminiscent of a Korringa-type relaxation behavior. In this picture the ESR properties below T_t are dominated by the slowing down of the polaronic hopping process. The charge fluctuations persist down to the temperature T* ~ 410 K, below which the system can be described as a charge-ordered assembly of Mn3+ and Mn4+ spins.
@article{arxiv.0810.1641,
title = {Electron Spin Resonance across the Charge-ordering Transition in YBaMn2O6},
author = {D. Zakharov and J. Deisenhofer and H. -A. Krug von Nidda and T. Nakajima and Y. Ueda and A. Loidl},
journal= {arXiv preprint arXiv:0810.1641},
year = {2009}
}