具有交换各向异性的Fe_(3)O_(4)/α-Fe_(2)O_(3)核壳结构诱导的偏置现象  

Exchange bias induced by anisotropy on Fe_(3)O_(4)/α-Fe_(2)O_(3) core-shell structure

作　　者：赵云 蔡伟强 孙梓健 马锡英[1] 张晓渝 ZHAO Yun;CAI Weiqiang;SUN Zijian;MA Xiying;ZHANG Xiaoyu(School of Physical Science and Technology,SUST,Suzhou 215009,China)

机构地区：[1]苏州科技大学物理科学与技术学院,江苏苏州215009

出　　处：《苏州科技大学学报（自然科学版）》2024年第1期43-47,共5页Journal of Suzhou University of Science and Technology（Natural Science Edition）

基　　金：国家自然科学基金项目(61107093);江苏省高等学校自然科学研究项目(19KJA140001)。

摘　　要：采用Fe_(3)O_(4)颗粒的固相氧化反应制备出Fe_(3)O_(4)/α-Fe_(2)O_(3)核壳结构颗粒,并在低于反铁磁奈尔温度(955 K)高磁场(1 T)下进行场冷却,对亚铁磁/反铁磁Fe_(3)O_(4)/α-Fe_(2)O_(3)核壳结构的晶体结构、微观形貌以及磁学性能进行了测试和分析。实验发现,随着亚铁磁Fe_(3)O_(4)表面反铁磁层α-Fe_(2)O_(3)厚度的增加,颗粒矫顽力从约57 Oe增大到4525 Oe,磁滞回线呈现出蜂腰状。当反铁磁层厚度约为533 nm时,核壳结构磁滞回线出现增强的交换偏置场~601 Oe。理论计算表明,由于亚铁磁性的Fe_(3)O_(4)和反铁磁性的α-Fe_(2)O_(3)界面处存在相互交换作用,当反铁磁厚度大于510 nm时,核壳结构各向异性能和塞曼能都高于界面交换能时,亚铁磁/反铁磁核壳体系会出现交换偏置的增强现象。In this paper,Fe_(3)O_(4)/α-Fe_(2)O_(3) core-shell structures were prepared by solid phase oxidation reaction from Fe_(3)O_(4) particles,and field cooling was carried out at a high magnetic field(1 T)lower than antiferromagnetic Neel temperature(955 K).The crystal structure,microstructure and magnetic properties of Fe_(3)O_(4)/α-Fe_(2)O_(3) core-shell structures were measured and analyzed.It is found that the coercivity of the particles increases from about 57 Oe to 4525 Oe and that the hysteresis loop exhibits a wasp-waisted shape with the increase of the antiferromagnetic layerα-Fe_(2)O_(3) thickness on the surface of ferrimagnetic Fe_(3)O_(4).When the thickness of the antiferromagnetic layer is about 533 nm,the hysteresis loop shows the enhanced exchange bias field of~601 Oe.The theoretical calculation shows that the exchange bias of the ferrimagnetic/antiferromagnetic core-shell microstructures is enhanced due to the ferromagnetic interaction at the interfaces.The anisotropy energy and Zeeman energy of the core-shell structures higher than the interfacial exchange energy,respectively,dominates the exchange bias when the antiferromagnetic thickness is higher than 510 nm.

关 键 词：Fe_(3)O_(4)/α-Fe_(2)O_(3)核壳结构 亚铁磁/反铁磁体系 交换偏置 蜂腰磁滞回线 

分 类 号：O469[理学—凝聚态物理]