scholarly journals Strong Interfacial Perpendicular Magnetic Anisotropy in Exchange-Biased NiO/Co/Au and NiO/Co/NiO Layered Systems

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1237
Author(s):  
Mateusz Kowacz ◽  
Błażej Anastaziak ◽  
Marek Schmidt ◽  
Feliks Stobiecki ◽  
Piotr Kuświk
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Bias ◽  
Direct Contact ◽  
Domain Walls ◽  
Perpendicular Magnetic Anisotropy ◽  
Bias Field ◽  
Layered Systems ◽  
Ferromagnetic Layers ◽  
Out Of Plane ◽  
And Control

The ability to induce and control the perpendicular magnetic anisotropy (PMA) of ferromagnetic layers has been widely investigated, especially those that offer additional functionalities (e.g., skyrmion stabilization, voltage-based magnetization switching, rapid propagation of domain walls). Out-of-plane magnetized ferromagnetic layers in direct contact with an oxide belong to this class. Nowadays, investigation of this type of system includes antiferromagnetic oxides (AFOs) because of their potential for new approaches to applied spintronics that exploit the exchange bias (EB) coupling between the ferromagnetic and the AFO layer. Here, we investigate PMA and EB effect in NiO/Co/Au and NiO/Co/NiO layered systems. We show that the coercive and EB fields increase significantly when the Co layer is coupled with two NiO layers, instead of one. Surrounding the Co layer only with NiO layers induces a strong PMA resulting in an out-of-plane magnetized system can be obtained without a heavy metal/ferromagnetic interface. The PMA arises from a significant surface contribution (0.74 mJ/m2) that can be enhanced up to 0.99 mJ/m2 by annealing at moderate temperatures (~450 K). Using field cooling processes for both systems, we demonstrate a wide-ranging control of the exchange bias field without perturbing other magnetic properties of importance.

scholarly journals Tailoring Perpendicular Exchange Bias Coupling in Au/Co/NiO Systems by Ion Bombardment

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 813 ◽  
Author(s):  
Piotr Kuświk ◽  
Alexander Gaul ◽  
Maciej Urbaniak ◽  
Marek Schmidt ◽  
Jacek Aleksiejew ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Exchange Bias ◽  
Perpendicular Magnetic Anisotropy ◽  
Ion Bombardment ◽  
Film Deposition ◽  
Layered System ◽  
Plane Anisotropy ◽  
Ferromagnetic Layers ◽  
Level Model

Here, we systematically investigated the influence of ion bombardment with different fluences on the strength and direction of the exchange bias coupling in Au/Co/NiO systems with perpendicular magnetic anisotropy of the Co layer. We found that the direction of the exchange bias coupling can be reversed as a result of ion bombardment performed in an external magnetic field which is in the opposite direction to the magnetic field applied during film deposition. Moreover, the strength of the exchange bias coupling can be tailored by varying the ion fluence. These results show behaviors similar to the results found for systems of ferromagnetic layers with in-plane anisotropy. Our experimental work, supported by a two-energy-level model, demonstrates that exchange bias coupling can be tuned in a layered system with perpendicular magnetic anisotropy using ion bombardment.

Chirally coupled nanomagnets

Science ◽  
2019 ◽  
Vol 363 (6434) ◽  
pp. 1435-1439 ◽  
Author(s):  
Zhaochu Luo ◽  
Trong Phuong Dao ◽  
Aleš Hrabec ◽  
Jaianth Vijayakumar ◽  
Armin Kleibert ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Domain Walls ◽  
Logic Gates ◽  
Bias Field ◽  
Electric Control ◽  
Nonvolatile Memories ◽  
Magnetic Layers ◽  
Out Of Plane ◽  
Free Current ◽  
Moriya Interaction

Magnetically coupled nanomagnets have multiple applications in nonvolatile memories, logic gates, and sensors. The most effective couplings have been found to occur between the magnetic layers in a vertical stack. We achieved strong coupling of laterally adjacent nanomagnets using the interfacial Dzyaloshinskii-Moriya interaction. This coupling is mediated by chiral domain walls between out-of-plane and in-plane magnetic regions and dominates the behavior of nanomagnets below a critical size. We used this concept to realize lateral exchange bias, field-free current-induced switching between multistate magnetic configurations as well as synthetic antiferromagnets, skyrmions, and artificial spin ices covering a broad range of length scales and topologies. Our work provides a platform to design arrays of correlated nanomagnets and to achieve all-electric control of planar logic gates and memory devices.

scholarly journals Origin of perpendicular magnetic anisotropy in amorphous thin films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel Lordan ◽  
Guannan Wei ◽  
Paul McCloskey ◽  
Cian O’Mathuna ◽  
Ansar Masood
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Perpendicular Magnetic Anisotropy ◽  
Functional Materials ◽  
Spin Reorientation ◽  
Amorphous Films ◽  
Amorphous Thin Films ◽  
Magnetic Performance ◽  
Out Of Plane ◽  
Sputtering Pressure

AbstractThe emergence of perpendicular magnetic anisotropy (PMA) in amorphous thin films, which eventually transforms the magnetic spins form an in-plane to the out-of-plane configuration, also known as a spin-reorientation transition (SRT), is a fundamental roadblock to attain the high flux concentration advantage of these functional materials for broadband applications. The present work is focused on unfolding the origin of PMA in amorphous thin films deposited by magnetron sputtering. The amorphous films were deposited under a broad range of sputtering pressure (1.6–6.2 mTorr), and its effect on the thin film growth mechanisms was correlated to the static global magnetic behaviours, magnetic domain structure, and dynamic magnetic performance. The films deposited under low-pressure revealed a dominant in-plane uniaxial anisotropy along with an emerging, however feeble, perpendicular component, which eventually evolved as a dominant PMA when deposited under high-pressure sputtering. This change in the nature of anisotropy redefined the orientation of spins from in-plane to out-of-plane. The SRT in amorphous films was attributed to the dramatic change in the growth mechanism of disorder atomic structure from a homogeneously dispersed to a porous columnar microstructure. We suggest the origin of PMA is associated with the columnar growth of the amorphous films, which can be eluded by a careful selection of a deposition pressure regime to avoid its detrimental effect on the soft magnetic performance. To the author’s best knowledge, no such report links the sputtering pressure as a governing mechanism of perpendicular magnetisation in technologically important amorphous thin films.

scholarly journals Strain-induced perpendicular magnetic anisotropy and Gilbert damping of Tm3Fe5O12 thin films

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Oana Ciubotariu ◽  
Anna Semisalova ◽  
Kilian Lenz ◽  
Manfred Albrecht
Keyword(s):  
Film Thickness ◽  
Magnetic Anisotropy ◽  
Tensile Strain ◽  
Easy Axis ◽  
Perpendicular Magnetic Anisotropy ◽  
Gilbert Damping ◽  
Sample Plane ◽  
Iron Garnets ◽  
Out Of Plane ◽  
Magnetic Easy Axis

AbstractIn the attempt of implementing iron garnets with perpendicular magnetic anisotropy (PMA) in spintronics, the attention turned towards strain-grown iron garnets. One candidate is Tm3Fe5O12 (TmIG) which possesses an out-of-plane magnetic easy axis when grown under tensile strain. In this study, the effect of film thickness on the structural and magnetic properties of TmIG films including magnetic anisotropy, saturation magnetization, and Gilbert damping is investigated. TmIG films with thicknesses between 20 and 300 nm are epitaxially grown by pulsed laser deposition on substituted-Gd3Ga5O12(111) substrates. Structural characterization shows that films thinner than 200 nm show in-plane tensile strain, thus exhibiting PMA due to strain-induced magnetoelastic anisotropy. However, with increasing film thickness a relaxation of the unit cell is observed resulting in the rotation of the magnetic easy axis towards the sample plane due to the dominant shape anisotropy. Furthermore, the Gilbert damping parameter is found to be in the range of 0.02 ± 0.005.

Magnetoresistance of Nanoscale Domain Walls Formed in Arrays of Parallel Nanowires

SPIN ◽  
2019 ◽  
Vol 09 (01) ◽  
pp. 1950004
Author(s):  
Jingchun Wang ◽  
Floriano Cuccureddu ◽  
Rafael Ramos ◽  
Cormac Ó. Coileáin ◽  
Igor V. Shvets ◽  
...  
Keyword(s):  
Thin Films ◽  
Domain Wall ◽  
Exchange Interaction ◽  
Exchange Bias ◽  
Room Temperature ◽  
Domain Walls ◽  
Nanowire Array ◽  
Bias Field ◽  
Nanowire Arrays ◽  
Exchange Bias Field

We present the possibility of enhancing magnetoresistance (MR) by controlling nanoscale domain wall (DW) width in a planar nanowire array. Results based on micromagnetic calculations show that DW width decreases with increasing exchange bias field and decreases with reducing exchange interaction between neighboring nanowires. Fe/Fe3O4 nanowire arrays were grown on [Formula: see text]-plane sapphire to demonstrate the feasibility of this concept, and an enhanced MR ratio of 3.7% was observed at room temperature. compared with flat and stepped Fe3O4 thin films.

Sign in / Sign up

Export Citation Format

Share Document