Abstract In BiFeO3-based ferromagnet/anitferromagnet (FM/AFM) bilayers, field cooling is required through the Neel temperature to achieve significant exchange bias (EB) at room temperature (RT). In this work, NiFe2O4/BiFeO3 (NFO/BFO) all-oxide bilayer films were selected and deposited on SrTiO3 substrates by pulsed laser deposition to avoid the possible interfacial oxidization during the field cooling process. In combination with X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM) characterizations, the NFO/BFO bilayers are shown to have good crystalline layered structure. After field cooling at various temperatures, the samples show sizable EB effect at low temperature region, which is attributed to spin-glass-pinned effect. More importantly, significant EB can be obtained at RT after the sample was field cooled from temperatures higher than 400 K. The maximal values of the exchange bias field (HE) and the ratio between HE and coercivity (i.e. HE/HC) are 48 Oe and 0.6 at RT, respectively. The EB effect at RT is considered to result from the pinned and uncompensated spins near the NFO-BFO interface.

中文翻译：

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NiFe2O4/BiFeO3双层中交换偏压的温度依赖性

摘要 在基于 BiFeO3 的铁磁体/反铁磁体 (FM/AFM) 双层中，需要通过尼尔温度进行场冷却，以在室温 (RT) 下实现显着的交换偏置 (EB)。在这项工作中，选择 NiFe2O4/BiFeO3 (NFO/BFO) 全氧化物双层薄膜并通过脉冲激光沉积将其沉积在 SrTiO3 衬底上，以避免在场冷却过程中可能出现的界面氧化。结合 X 射线衍射 (XRD)、X 射线光电子能谱 (XPS) 和透射电子显微镜 (TEM) 表征，NFO/BFO 双层显示具有良好的结晶层状结构。在不同温度下场冷却后，样品在低温区表现出相当大的 EB 效应，这归因于自旋玻璃钉扎效应。更重要的是，在将样品从高于 400 K 的温度场冷却后，可以在室温下获得显着的 EB。交换偏置场 (HE) 的最大值以及 HE 与矫顽力之间的比率（即 HE/HC）分别为 48 Oe 和 0.6 RT，分别。RT 处的 EB 效应被认为是由 NFO-BFO 界面附近的固定和未补偿自旋引起的。