We study the tunneling magnetoresistance in the ensembles of ferromagnetic granules with random easy axes of magnetic anisotropy taking into account the exchange interaction between granules. It is shown that due to the exchange interaction magnetoresistance is effectively decoupled from magnetization, i.e. the strongest negative magnetoresistance can be observed at the field where magnetization is almost saturated. Under some conditions, the sign of magnetoresistance can be reversed and tunneling magnetoresistance can become positive at certain magnetic fields. Our theory agrees with measurements of magnetoresistance in ensembles of Fe granules in SiCxNy matrix.

中文翻译：

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具有交换相互作用和磁各向异性随机易轴的铁磁颗粒集合中的隧道磁阻。

考虑到颗粒之间的交换相互作用，我们研究了具有随机易磁各向异性轴的铁磁颗粒集合中的隧道磁阻。结果表明，由于交换相互作用，磁阻有效地与磁化解耦，即在磁化几乎饱和的磁场中可以观察到最强的负磁阻。在某些条件下，磁阻的符号可以反转，隧道磁阻在某些磁场下可以变为正。我们的理论与 SiCxNy 基体中铁颗粒集合中的磁阻测量结果一致。