Activation of antiferromagnetic domain switching in exchange-coupled Fe/CoO/MgO(001) systems

Li, Q.; Chen, G.; P., T.; Zhu, Jianming; N'Diaye, A. T.; Sun, Li; Gu, Tianyu; Yan, Huirong; Liang, Jianhui; Li, R. W.; Won, C.; Ding, Haifeng; Qiu, Z. Q.; Wu, Y. Z.

doi:10.1103/physrevb.91.134428

Cited by 23 publications

(31 citation statements)

References 33 publications

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“…Antiferromagnetic domains play an essential role in this context which makes their detailed understanding an important challenge. 95 Research in antiferromagnetic domain walls and other textures falls also naturally into this category of future studies.…”

Section: Discussionmentioning

confidence: 99%

Antiferromagnetic spintronics

et al. 2016

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Antiferromagnetic materials are magnetic inside, however, the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets invisible on the outside. It also implies that if information was stored in antiferromagnetic moments it would be insensitive to disturbing external magnetic fields, and the antiferromagnetic element would not affect magnetically its neighbors no matter how densely the elements were arranged in a device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. The outstanding question is how to efficiently manipulate and detect the magnetic state of an antiferromagnet. In this article we give an overview of recent works addressing this question. We also review studies looking at merits of antiferromagnetic spintronics from a more general perspective of spin-ransport, magnetization dynamics, and materials research, and give a brief outlook of future research and applications of antiferromagnetic spintronics.Interesting and useless -this was the common perception of antiferromagnets expressed quite explicitly, for example, in the 1970 Nobel lecture of Louis Néel.1 Connecting to this traditional notion we can define antiferromagnetic spintronics as a field that makes antiferromagnets useful and spintronics more interesting. Below we give an overview of this emerging field whose aim is to complement or replace ferromagnets in active components of spintronic devices.We recall some key physics roots of the field and first concepts of spintronic devices based on antiferromagnetic counterparts of the non-relativistic giantmagnetoresistance and spin-transfer-torque phenomena. 2We then focus on electrical reading and writing of information, combined with robust storage, that can be realized in antiferromagnetic memories via relativistic magnetoresistance and spin torque effects.3,4 Related to these topics is the research of spintronic devices in which antiferromagnets act as efficient generators, detectors, and transmitters of spin currents. This will lead us to studies exploring fast dynamics in antiferromagnets 5 and different types of antiferromagnetic materials. They range from insulators to superconductors. Here we comment also on the relation between crystal antiferromagents and synthetic antiferromagnets, with the latter ones playing an important role in spintronic sensor and memory devices.6 In concluding remarks we outline some of the envisaged future directions of research and potential applications of antiferromagnetic spintronics. Equilibrium properties and magnetic storage in antiferromagnetsThe understanding of equilibrium properties of ferromagnets has been guided by the notion of a global molecular field, introduced by Pierre Weiss.1 The theory starts from the Curie law for paramagnets with the inverse susceptibility proportional to temperature, χ −1 ∼ T . It further assumes that the externally ap...

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Section: Discussionmentioning

confidence: 99%

Antiferromagnetic spintronics

et al. 2016

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“…A 10 nm MgO seed layer was deposited at 500 o C before the Fe/CoO growth. The 5 nm CoO film was grown by reactive deposition of Co at an oxygen pressure of 1.0×10 -6 Torr at room temperature [25,26] [23,25,26]. Finally, this sample was capped with 4 nm MgO as a protective layer.…”

Section: ⅱ Experimentsmentioning

confidence: 99%

“…However, the random spin orientations of AFM polycrystalline grains, which are usually employed for such studies, complicate the spin switching, prohibiting an explicit exploration of the AFM spin switching process. Using single-crystalline Fe/CoO bilayers, it was recently demonstrated that the CoO AFM domain switching process can be revealed by the evolution of the Fe remanent state [23]. It was found that the AFM CoO spin switching in the Fe/CoO system is characterized by an energy barrier dominated thermal excitations.…”

Section: ⅰ Introductionmentioning

confidence: 99%

Field dependence of antiferromagnetic domain switching in epitaxial Fe/CoO/MgO(001) systems

Yang

et al. 2017

Phys. Rev. B

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Utilizing the magneto-optic Kerr effect and Kerr microscopy measurements, we investigated the antiferromagnetic (AFM) domain switching process at different magnetic fields in a single crystalline Fe/CoO bilayer grown on MgO(001) substrate. In spite of the zero-net magnetic moment in CoO layer, we find that the activation energy barrier of CoO AFM domain switching decreased at larger magnetic field. To separate the different behaviors of domain nucleation and domain wall motion during the CoO spin switching process, a new analytical method was developed. Using this method, we found that the CoO domain nucleation energy barrier exhibited a jump at a critical magnetic field while the CoO domain wall motion experienced only a tiny energy barrier variation. The field-dependent behaviors of the energy barriers were attributed to the formation of a spiral domain wall in the Fe layer during its magnetization reversal and this was supported by micromagnetic simulations.

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“…This mystery was resolved by XMLD measurement which shows that exchange bias is associated only with a small amount of pinned uncompensated AFM spins [17] which could have a wide distribution from the FM/AFM interface to the bulk AFM layer [18]. In contrast, the majority compensated AFM spins, depending on their rotatable or frozen nature [19], are responsible for different types of the magnetic anisotropies in the FM layer [20,21]. Regarding the key question of how the AFM spins respond to the FM magnetization reversal, the most mysterious issue concerns the so-called Mauri's model in which FM/AFM interfacial coupling is presumed to twist the AFM spins into a 180°spiral wall during the FM magnetization reversal and subsequently creates an exchange bias [22].…”

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confidence: 99%

“…The different Néel temperatures (T N ) of CoO (T N ∼ 290) and NiO (T N ∼ 520 K) are expected to lead to an AFM Co 0.5 Ni 0.5 O film on vicinal Ag(001) with T N > 300 K [31][32][33] and with an in-plane spin axis perpendicular to the atomic steps [27]. By taking XAS [19][20][21][26][27][28] We then studied the NiO spiral wall in Fe(1.5 nm)/ NiO(d NiO )/Co 0.5 Ni 0.5 O(8 nm)/vicinal Ag(001) by applying a 4000 Oe magnetic field ( H ) to align the Fe magnetization to the x and y axis, respectively. In the thin limit of NiO thickness at d NiO = 3 nm, we observe the same XAS spectra at Co Next, we measured the NiO XMLD in Fe(1.5 nm)/ NiO(wedge)/Co 0.5 Ni 0.5 O(8 nm)/vicinal Ag(001) where the NiO wedge ensures the same Fe/NiO interface so that the XMLD result should reveal systematically the dependence of the NiO spiral wall on d NiO .…”

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confidence: 99%

Chirality switching of an antiferromagnetic spiral wall and its effect on magnetic anisotropy

Yang

N’Diaye

et al. 2019

Phys. Rev. Materials

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An antiferromagnetic NiO spiral wall in Fe/NiO/Co 0.5 Ni 0.5 O/vicinal Ag(001) was created by rotating Fe magnetization and investigated using x-ray magnetic linear dichroism (XMLD). Different from the Mauri's 180°s piral wall, we find that the NiO spiral wall always switches its chirality at ∼90 • rotation of the Fe magnetization, and unwinds the spiral wall back to a single domain with a further rotation of the Fe magnetization from 90°to 180°. The effect of this chirality switching on the magnetic anisotropy was studied using rotational magneto-optic Kerr effect (ROTMOKE) on Py/NiO/Co 0.5 Ni 0.5 O/vicinal Ag(001). We find that the original Mauri's model has to be corrected by an energy folding due to the chirality switching, which consequently converts the exchange bias from the Mauri's 180°spiral wall into a uniaxial anisotropy and a negative fourfold anisotropy.

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Activation of antiferromagnetic domain switching in exchange-coupled Fe/CoO/MgO(001) systems

Cited by 23 publications

References 33 publications

Antiferromagnetic spintronics

Antiferromagnetic spintronics

Field dependence of antiferromagnetic domain switching in epitaxial Fe/CoO/MgO(001) systems

Chirality switching of an antiferromagnetic spiral wall and its effect on magnetic anisotropy

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