Abstract Polycrystalline ceramics of Co(Cr 1- x Fe x ) 2 O 4 (0 ≤ x ≤ 0.12) were experimentally studied based on a series of temperature and time-dependent dc magnetic measurements using different magnetic field histories. Magnetization in field cooling process was continuously decreased for doping content x in the range of 0 ≤ x ≤ 0.04. Remarkable negative magnetization is observed when x reaches to 0.06 and persists up to x = 0.1. Two-sublattice model is established and competition of the two magnetic sublattices is responsible for the phenomenon. The magnetic switching effect is realized just by changing the magnitude of the applied magnetic field and double magnetocaloric effects are obtained. These unique features under low magnetic fields show attractive for application in spintronic devices due to that the magnetic state can effectively be tuned through magnetic field or temperature. Besides, the system exhibits both positive and negative exchange bias fields which are considered to be originating from the unidirectional anisotropy of exchange coupling of antiferromagnetic/ferromagnetic phases and spin reorientation of the two sublattices magnetic moments, respectively.

中文翻译：

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Fe掺杂的CoCr 2 O 4 中的负磁化和交换偏置效应

摘要 基于一系列温度和时间相关的直流磁测量，使用不同的磁场历史，对 Co(Cr 1- x Fe x ) 2 O 4 (0 ≤ x ≤ 0.12) 多晶陶瓷进行了实验研究。掺杂量x在0≤x≤0.04范围内，场冷过程中的磁化强度不断降低。当 x 达到 0.06 并持续到 x = 0.1 时，观察到显着的负磁化。建立了两个亚晶格模型，两个磁性亚晶格的竞争是造成这种现象的原因。只需改变外加磁场的大小即可实现磁开关效应，获得双重磁热效应。由于可以通过磁场或温度有效地调节磁态，因此这些在低磁场下的独特特征对自旋电子器件的应用具有吸引力。此外，该系统同时表现出正负交换偏置场，这被认为分别源于反铁磁/铁磁相交换耦合的单向各向异性和两个亚晶格磁矩的自旋重定向。