BiFeO3/Ni81Fe19磁性双层膜中的交换偏置及其热稳定性研究

研究了磁场诱导生长的BiFeO₃/Ni₁₈Fe₁₉磁性双层膜中 的交换偏置及其热稳定性. 结果表明: BiFeO₃/Ni₁₈Fe₁₉双层膜中的交换偏置场H_ex未表现出明显的磁练习效应. 在负饱和磁场等待过程中, BiFeO₃/Ni₁₈Fe₁₉双层膜磁滞回线的前支和后支曲 线都随着在负饱和磁场中等待时间t_sat的增加向正场方向偏移. 交换偏置场H_ex的大小随着等待时间t_sat的增加而减小, 矫顽力H_c基本不变. 交换偏置场H_ex的大小随测量温度T_m的升高变化不明显, 表现出良好的热稳定性; 但矫顽力H_c随T_m的升高而显著减小. 良好的热稳定性应该来源于铁电性和反铁磁性间的共同耦合作用.关键词：多铁性磁性薄膜交换偏置热稳定性

Exchange bias in BiFeO3/Ni81Fe19 magnetic films and its thermal stability

This paper deals with the exchange bias and its thermal stability in magnetic BiFeO₃/Ni₈₁Fe₁₉ bilayer sputtered under an electromagnetic field. The results show that the BiFeO₃/Ni₁₈Fe₁₉ bilayer presents an in-plane uniaxial magnetic anisotropy and a significant exchange bias effect, however the exchange bias field H_ex in the BiFeO₃/Ni₁₈Fe₁₉ bilayer does not show a visible training effect. The forward and recoil loop shifts towards positive fields, while holding the film in a negative saturation field. H_ex decreases monotonously with the increase in the holding time (t_sat), whereas H_c is almost the same. With increasing temperature T_m, H_ex will not alter significantly, which means that H_ex is not sensitive to the temperature, showing a good thermal stability. However, H_c may reduce rapidly with the increase in temperature. We believe that the good thermal stability may result from the coupling between ferroelectric and antiferromagnetic moments in BiFeO₃.
Keywords：multiferroicmagnetic filmsexchange biasthermal stability