Crossover from Spin-Flop Coupling to Collinear Spin Alignment in Antiferromagnetic/Ferromagnetic Nanostructures

Folven, Erik; Schöll, A.; Young, A. T.; Retterer, Scott T.; Boschker, Jos E.; Tybell, Thomas; Takamura, Yayoi; Grepstad, J. K.

doi:10.1021/nl300361e

Cited by 35 publications

(35 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, this spin-flop coupling was experimentally reported for extended LFO/LSMO thin films [15] and micrometer sized magnets [16]. However, we have recently demonstrated that shape-induced domain stabilization may override this interface exchange coupling and force a collinear spin alignment in embedded LFO/LSMO nanomagnets below a certain critical width of approximately 500 nm [9]. In the rectangular nanomagnets (500nm×2µm) investigated in this study, edge-stabilized domains prevail ( Fig.…”

supporting

confidence: 61%

See 1 more Smart Citation

Controlling the switching field in nanomagnets by means of domain-engineered antiferromagnets

et al. 2015

View full text Add to dashboard Cite

Using soft x-ray spectromicroscopy, we investigate the magnetic domain structure in embedded nanomagnets defined in La0.7Sr0.3MnO3 thin films and LaFeO3/La0.7Sr0.3MnO3 bilayers. We find that shape-controlled antiferromagnetic domain states give rise to a significant reduction of the switching field of the rectangular nanomagnets. This is discussed in the framework of competition between an intrinsic spin-flop coupling and shape anisotropy. The data demonstrates that shape effects in antiferromagnets may be used to control the magnetic properties in nanomagnets. Main text:The coupling of an antiferromagnet to an adjacent ferromagnet may induce a unidirectional anisotropy, known as exchange bias [1], which is commonly exploited in spintronic devices [2,3]. This effect is utilized to achieve independent control of the magnetization in the different layers of magnetic tunnel junctions and spin valves used, e.g., in hard drive read heads and magnetic random access memory. More recently, the discovery of electric control of exchange bias has gained considerable attention [4,5]. This finding adds a degree of freedom to spintronic engineering. Furthermore, the increased coercivity typically arising from antiferromagnetic/ferromagnetic (AF/FM) coupling may help overcome superparamagnetism [6]

show abstract

supporting

confidence: 61%

“…4(c)). While the interface exchange coupling ℱ favors a perpendicular alignment of the spins in the LFO and LSMO layers, as observed experimentally for blanket films and larger micromagnets [9], shape anisotropy predominates and gives rise to a collinear alignment of and for the magnets displayed in Fig. 2.…”

supporting

confidence: 59%

Controlling the switching field in nanomagnets by means of domain-engineered antiferromagnets

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The first effect occurs when the shape-imposed easy axis is perpendicular to the "proper" easy magnetic axis of the crystal (e.g., induced by an external magnetic field) 10 . The constants of intrinsic and shape-induced magnetic anisotropy are of opposite signs; so, there is a critical aspect ratio a/b, at which spin-flop transition of the AFM vector takes place.…”

Section: Discussionmentioning

confidence: 99%

Shape-induced anisotropy in antiferromagnetic nanoparticles

Gomonay¹,

Kondovych²,

Локтев³

2014

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

High fraction of the surface atoms considerably enhances the influence of size and shape on the magnetic and electronic properties of nanoparticles. Shape effects in ferromagnetic nanoparticles are well understood and allow to set and control the parameters of a sample that affect its magnetic anisotropy during production. In the present paper we study the shape effects in the other widely used magnetic materials -antiferromagnets, -which possess vanishingly small or zero macroscopic magnetization. We take into account the difference between the surface and bulk magnetic anisotropy of a nanoparticle and show that the effective magnetic anisotropy depends on the particle shape and crystallographic orientation of its faces. Corresponding shape-induced contribution to the magnetic anisotropy energy is proportional to the particle volume, depends on magnetostriction, and can cause formation of equilibrium domain structure. Crystallographic orientation of the nanoparticle surface determines the type of domain structure. The proposed model allows to predict the magnetic properties of antiferromagnetic nanoparticles depending on their shape and treatment.

show abstract

“…PhotoEmission Electron Microscopy (PEEM), with contrast enabled by X-ray Magnetic Linear Dichroism (XMLD), provides direct imaging of AF domains with better than 100 nm resolution [16]. Based on differences in absorption of x-rays with linear polarization, XMLD-PEEM has offered valuable insights into the microscopic magnetic properties of AF films [17] and ferromagnet / AF interfaces [18,19]. The measured intensity varies as I 0 + I 2 cos 2 α, where α is the angle between the x-ray polarization and the spin axis [20], so is equally present for AF and FM materials, similar to AMR.…”

mentioning

confidence: 99%

Imaging Current-Induced Switching of Antiferromagnetic Domains in CuMnAs

et al. 2017

View full text Add to dashboard Cite

The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using X-ray Magnetic Linear Dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the antiferromagnetic domain structure in microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between the average domain orientation and the anisotropy of the electrical resistance is demonstrated, with both showing reproducible switching in response to orthogonally applied current pulses. However, the behavior is inhomogeneous at the submicron level, highlighting the complex nature of the switching process in multi-domain antiferromagnetic films.Antiferromagnetic (AF) materials are of increasing interest both for fundamental physics and applications. Recent advances in detecting and manipulating AF order electrically have opened up new prospects for these materials in basic and applied spintronics research [1][2][3][4][5][6][7]. Of particular interest is the Néel order spin-orbit torque (NSOT) [6], recently demonstrated in the collinear AF CuMnAs [7], where a current-induced local spin polarization can exert a rotation of the magnetic sublattices. NSOT is closely analogous to the spin-orbit torque in ferromagnets with broken inversion symmetry, in which electrical currents induce effective magnetic fields that can be used to switch the magnetization direction [8,9]. The tetragonal CuMnAs lattice [10] is inversion symmetric, so that zero net spin polarization is generated by a uniform electric current. However, its Mn spin sublattices form inversion partners, resulting in local effective fields of opposite sign on the AF-coupled Mn sites [6,11]. These staggered current-induced fields can be large enough to cause a non-volatile rotation of the AF spin axis [7].Current-induced rotations of AF moments can be detected electrically using anisotropic magnetoresistance (AMR), a dependence on the relative orientation of the current and spin axes which is present in both ferromagnetic and AF materials [12][13][14][15]. This provides only spatially averaged information over the probed area of the device, which may be several microns or larger. PhotoEmission Electron Microscopy (PEEM), with contrast enabled by X-ray Magnetic Linear Dichroism (XMLD), provides direct imaging of AF domains with better than 100 nm resolution [16]. Based on differences in absorption of x-rays with linear polarization, XMLD-PEEM has offered valuable insights into the microscopic magnetic properties of AF films [17] and ferromagnet / AF interfaces [18,19]. The measured intensity varies as I 0 + I 2 cos 2 α, where α is the angle between the x-ray polarization and the spin axis [20], so is equally present for AF and FM materials, similar to AMR. The XMLD amplitude given by I 2 also depends on the orientation of the x-ray polarization with respect to the crystalline axes [21,22], and the signal is sensitive to domains within the top few nanometers of the surface.Here, we combin...

show abstract

Crossover from Spin-Flop Coupling to Collinear Spin Alignment in Antiferromagnetic/Ferromagnetic Nanostructures

Cited by 35 publications

References 23 publications

Controlling the switching field in nanomagnets by means of domain-engineered antiferromagnets

Controlling the switching field in nanomagnets by means of domain-engineered antiferromagnets

Shape-induced anisotropy in antiferromagnetic nanoparticles

Imaging Current-Induced Switching of Antiferromagnetic Domains in CuMnAs

Contact Info

Product

Resources

About