Blocking Temperature Engineering in Exchange-Biased CoFeB/IrMn Bilayer

Abstract

In this paper we report on the magnetic and chemical characterization of the exchange-biased CoFeB/IrMn bilayers, grown by magnetron sputtering on a Si-based platform and capped by either a Ru or MgO/Ru overlayer. For Ru capping, the blocking temperature monotonously increases with the IrMn thickness within the investigated range (3.5-8 nm). On the contrary, for MgO/Ru capping, the exchange bias is inhibited below 6 nm, whereas above 6 nm the magnetic behavior is the same of Ru-capped films. The chemical analysis reveals a significant dependence of the Mn content from the capping layer for thin IrMn films (2.5 nm), whereas the difference disappears when IrMn becomes thick (7 nm). Our work suggests that a non-uniform composition of the IrMn films directly affects the exchange coupling at the IrMn/CoFeB interface.

Topological magnetotransport and electrical switching of sputtered antiferromagnetic Ir20Mn80

“…[48] As compared with other collinear or non-collinear metallic AFMs such as FeMn, PtMn, Mn 3 Sn, and Mn 3 Ge, the IrMn has the thinnest thickness to retain the AFM phase, [49][50][51] and maintains the antiferromagnetic phase for a considerable stoichiometric range. [52] And compared with other different Ir and Mn atomic ratios, the Ir 20 Mn 80 exhibits the maximum exchange coupling strength, [53] the highest blocking temperature, [53] together with strongest (111) texture, [54] and thus is of technological importance. [55] In this work, we experimentally show remarkable AHE in the magnetron-sputtered antiferromagnetic Ir 20 Mn 80 thin film.…”

Significant role of thermal effects in current-induced exchange bias field switching at antiferromagnet/ferromagnet interface

“…在非磁/铁磁异质结中, 热效应虽然能辅助 SOT降低磁矩翻转的电流密度 [18,19] , 但并不是磁 矩翻转的必要因素. 然而在非磁/反铁磁/铁磁多层 膜结构中, 阻塞温度T b 对反铁磁的厚度敏感, 例 如IrMn的厚度为几纳米时, 其T b 小于500 K [20][21][22] , 远小于CoFeB, Fe, Co等常见铁磁薄膜的居里温 度 [23,24] . 所以, 在SOT翻转过程中, 非磁/反铁磁/ 铁磁体系比非磁/铁磁体系更容易受到热效应的影 响, 尽管一些研究 [25][26][27] 异质结的阻塞温度T b [31] , 由图2(e)可知t IrMn = 3 nm和t IrMn = 4 nm时, T b 分别为360和400 K.…”