Hysteresis-free magnetization reversal of exchange-coupled bilayers with finite magnetic anisotropy
Hysteresis-free magnetization reversal of exchange-coupled bilayers with finite magnetic anisotropy
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DOI：
10.1103/physrevb.102.014429
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发表时间：
2020-04
影响因子：
3.7
通讯作者：
C. Vogler;M. Heigl;A. Mandru;B. Hebler;M. Marioni;H. Hug;M. Albrecht;D. Suess
中科院分区：
文献类型：
--
作者：
C. Vogler;M. Heigl;A. Mandru;B. Hebler;M. Marioni;H. Hug;M. Albrecht;D. Suess
由铁磁层和铁磁层组成的交换耦合结构在技术上变得越来越重要。我们通过实验证明了${\ mathm {Co}(0.2\phantom{\rule{0.16em}{0ex}}\ mathm {nm})/\ mathm {Ni}(0.4\phantom{\rule{0.16em}{0ex}}\ mathm {nm})/\ mathm {Pt}(0.6\phantom{\rule{0.16em}{0ex}}\ mathm {nm})}_{N}$多层交换耦合到20纳米厚的铁磁${\ mathm {Tb}}_{28}{\ mathm {Co}}_{14}{\ mathm {Fe}}_{58}$层，作为硬磁钉接层。此外，我们提出了详细的理论研究，通过微磁模拟，最重要的是，一个纯解析推导的条件下发生完全可逆性的磁化反转。如果在铁磁层反转过程中形成畴壁，产生克服铁磁层磁各向异性的本征硬轴偏置场，则会产生无磁滞回线。导出的条件进一步揭示了两层的磁各向异性和体积交换，以及交换耦合强度和铁磁层厚度对其可逆性起着重要作用。
Exchange-coupled structures consisting of ferromagnetic and ferrimagnetic layers become technologically more and more important. We show experimentally the occurrence of completely reversible, hysteresis-free minor loops of ${[\mathrm{Co}(0.2\phantom{\rule{0.16em}{0ex}}\mathrm{nm})/\mathrm{Ni}(0.4\phantom{\rule{0.16em}{0ex}}\mathrm{nm})/\mathrm{Pt}(0.6\phantom{\rule{0.16em}{0ex}}\mathrm{nm})]}_{N}$ multilayers exchange-coupled to a 20-nm-thick ferrimagnetic ${\mathrm{Tb}}_{28}{\mathrm{Co}}_{14}{\mathrm{Fe}}_{58}$ layer, acting as a hard magnetic pinning layer. Furthermore, we present detailed theoretical investigations by means of micromagnetic simulations and, most importantly, a purely analytical derivation for the condition of the occurrence of full reversibility in magnetization reversal. Hysteresis-free loops always occur if a domain wall is formed during the reversal of the ferromagnetic layer and generates an intrinsic hard-axis bias field that overcomes the magnetic anisotropy field of the ferromagnetic layer. The derived condition further reveals that the magnetic anisotropy and the bulk exchange of both layers, as well as the exchange coupling strength and the thickness of the ferromagnetic layer, play an important role for its reversibility.