Improvement of the interfacial Dzyaloshinskii-Moriya interaction by introducing a Ta buffer layer

Kim, Nam-Hui; Han, Dong‐Soo; Jung, Jinyong; Cho, Jaehun; Kim, June-Seo; Swagten, H.J.M.; You, Chun‐Yeol

doi:10.1063/1.4932550

Cited by 62 publications

(81 citation statements)

References 37 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A high signal-to-noise ratio of the measured BLS spectra is critical for accurately determining the measured spin wave frequency. The high quality of CoFeB with Ta seed layer may have contributed to the strong magnon signal 35 .The spin waves probed here are Damon-Eshback (DE) modes with propagation directions perpendicular to ( ). The spin wave dispersion is described by 30, 31…”

mentioning

confidence: 99%

Dzyaloshinskii-Moriya Interaction across an Antiferromagnet-Ferromagnet Interface

Sasaki

et al. 2017

Phys. Rev. Lett.

View full text Add to dashboard Cite

The antiferromagnet (AFM) / ferromagnet (FM) interfaces are of central importance in recently developed pure electric or ultrafast control of FM spins, where the underlying mechanisms remain unresolved. Here we report the direct observation of Dzyaloshinskii-Moriya interaction (DMI) across the AFM/FM interface of IrMn/CoFeB thin films. The interfacial DMI is quantitatively measured from the asymmetric spin-wave dispersion in the FM layer using Brillouin light scattering. The DMI strength is enhanced by a factor of 7 with increasing IrMn layer thickness in the range of 1-7.5 nm. Our findings provide deeper insight into the coupling at AFM/FM interface and may stimulate new device concepts utilizing chiral spin textures such as magnetic skyrmions in AFM/FM heterostructures.Control of spins in ferromagnets (FMs) utilizing antiferromagnets (AFMs) is an emerging branch of spintronics [1][2][3][4][5] . By placing an AFM layer adjacent to the FM layer, the unique electric, magnetic and transport properties of the AFM may be used to control the FM layer via interfacial coupling. Conventionally, the AFM layer has mostly played a passive role in device operations by either improving the hardness of FM via exchange bias [6][7][8] or increasing the magnetic damping of FM through spin pumping [9][10][11][12][13] . More recently, the AFMs have been used as active control elements, leading to promising breakthroughs in the electric and ultrafast control of FM spins. For instance, electric current-induced magnetization switching of FM without an external magnetic field has been realized in the AFM/FM systems [1][2][3][4] . These pioneering experiments have been shown to generate the pure spin current in the AFM or at the AFM/FM interface 1,2,[14][15][16] and to utilize the exchange bias to break the switching symmetry [1][2][3][4] . Moreover, coherent spin precession in the FM layer can be effectively excited by an ultrafast spin-exchange-coupling torque across the AFM/FM interface 5 . The laser pulse perturbs the AFM spin arrangement, which in turn generates an intense and non-thermal transient torque acting on the FM spins. Despite these promising achievements, certain limitations such as the incomplete magnetization switching by current remain in the AFM/FM system. Thus, elucidating interaction mechanisms across the AFM/FM interface is not only important from a scientific point of view, but also of great technologic relevance.In heterostructures with broken spatial inversion symmetry, the interfacial Dzyaloshinskii-Moriya interaction (DMI) has been identified as an important mechanism leading to a host of interesting phenomena. DMI promotes non-collinear spin alignments and determines the chirality and dynamics of chiral spin textures [17][18][19] . For instance, DMI stabilizes the magnetic skrymions and domain walls in the Né el configuration with certain chirality and lends a mechanism for driving skrymion and domain wall motion via spin torques [20][21][22][23][24][25] . Similarly, DMI likely contributes to the current-in...

show abstract

mentioning

confidence: 99%

Dzyaloshinskii-Moriya Interaction across an Antiferromagnet-Ferromagnet Interface

Sasaki

et al. 2017

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the DM interaction induces an asymmetry in the spin wave spectrum of thin ferromagnetic films [25,26]. Based on this asymmetry, recently extensive experimental efforts have been directed towards the measurement of the interfacial DM interaction by using inelastic light scattering [27][28][29], highly resolved spinpolarized electron energy loss [30] or propagating spin wave spectroscopy [31].The current-driven motion of domain walls is mainly investigated in ultrathin films and multilayers, paving the way for future applications in spintronic and logic devices [32,33]. In these systems, heavy nonmagnetic elements provide the strong spin-orbit coupling necessary for the appearance of the DM interaction in the adjacent magnetic layers.…”

mentioning

confidence: 99%

Domain-wall profiles in Co/Irn /Pt(111) ultrathin films: Influence of the Dzyaloshinskii-Moriya interaction

et al. 2016

View full text Add to dashboard Cite

We perform a study of domain walls in Co/Irn/Pt(111) (n = 0, . . . , 6) films by a combined approach of first-principles calculations and spin dynamics simulations. We determine the tensorial exchange interactions and the magnetic anisotropies for the Co overlayer in both FCC and HCP geometries, depending on the number of Ir buffer layers. We find strong ferromagnetic nearest-neighbor isotropic exchange interactions between the Co atoms and an out-of-plane magnetic anisotropy for the films in FCC geometry. Our simulations show that the magnetic domain walls are of Néel type, and their rotational sense (chirality) is changed upon the insertion of an Ir buffer layer as compared to the pristine Co/Pt(111) system. Our spin dynamics simulations indicate a twisting of the spins with respect to the planar domain wall profile on the triangular lattice. We discuss this domain wall twisting using symmetry arguments and in terms of an appropriate micromagnetic continuum model considering extra energy terms compared to the available literature. I. INTRODUCTIONEffective spin models are widely used to investigate the magnetic properties of solids. The breaking of inversion symmetry in noncentrosymmetric crystals, at surfaces or interfaces and the presence of the spin-orbit coupling lead to the appearance of an anisotropic exchange term beyond the isotropic Heisenberg interaction, which is known as the Dzyaloshinskii-Moriya (DM) interaction [1,2]. In collinear ferromagnetic systems, this type of interaction provides domain walls (DWs) with a chiral character [3][4][5][6][7][8], plays a key role in DW dynamics [9][10][11][12], and leads to the stabilization of isolated chiral skyrmions [13][14][15][16]. It may also cause the formation of noncollinear magnetic states [7,17] such as spin spirals [18,19] and condensated skyrmionic phases [16,[20][21][22][23][24]. Furthermore, the DM interaction induces an asymmetry in the spin wave spectrum of thin ferromagnetic films [25,26]. Based on this asymmetry, recently extensive experimental efforts have been directed towards the measurement of the interfacial DM interaction by using inelastic light scattering [27][28][29], highly resolved spinpolarized electron energy loss [30] or propagating spin wave spectroscopy [31].The current-driven motion of domain walls is mainly investigated in ultrathin films and multilayers, paving the way for future applications in spintronic and logic devices [32,33]. In these systems, heavy nonmagnetic elements provide the strong spin-orbit coupling necessary for the appearance of the DM interaction in the adjacent magnetic layers. Using the micromagnetic energy functional determined by Dzyaloshinskii[34], it has been demonstrated [3,35,36] that the DM interaction prefers a cycloidal or Néel-type rotation of spins within a domain wall in the C nv symmetry class to which the majority of these systems belong. The rotational plane of domain walls is determined by the competition between the DM interaction and the magnetostatic dipolar interaction preferring a h...

show abstract

“…The material parameters used are the same as for the LLG calculations including DMI as well. The strength of the DMI has been measured frequently in Pt/Co/Oxide systems; DMI constants range from D · d Co ∼ 0.3 pJ/m [9,31] to ∼ 2 pJ/m [32][33][34]. In our simulations, a DMI constant of -300 mT to model the data shown in Fig.…”

mentioning

confidence: 99%

Time Resolved Measurements of the Switching Trajectory of Pt/Co Elements Induced by Spin-Orbit Torques

et al. 2017

View full text Add to dashboard Cite

We report the experimental observation of spin-orbit torque induced switching of perpendicularly magnetized Pt/Co elements in a time resolved stroboscopic experiment based on high resolution Kerr microscopy. Magnetization dynamics is induced by injecting sub-nanosecond current pulses into the bilayer while simultaneously applying static in-plane magnetic bias fields. Highly reproducible homogeneous switching on time scales of several tens of nanoseconds is observed. Our findings can be corroborated using micromagnetic modelling only when including a field-like torque term as well as the Dzyaloshinskii-Moriya interaction mediated by finite temperature.Magnetization switching induced by spin-orbit torques (SOTs) generated by in plane (ip) current pulses in ferromagnet (FM)/heavy metal (HM) bilayers has attracted great attention in recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. A typical structure comprises a FM element with perpendicular magnetization structured on top of a HM conductor carrying the current. Technologically such a device has the advantage that the write current causing magnetization switching does not have to pass through a potential memory element itself thus avoiding its degradation [18]. Studying magnetization dynamics in such elements is of interest since the exact mechanisms enabling deterministic magnetization reversal remain to be disentangled. SOT driven magnetization reversal in HM/FM bilayers originates from a combination of effects which manifest themselves as field and damping like torques. These torques arise from bulk and interface effects such as the bulk spin Hall effect (SHE) or the interfacial inverse spin Galvanic effect (iSGE). Recent efforts have been dedicated to the understanding of the switching process induced by static or quasi-static currents [1,2,4,5,10,15,19]. However, the nature of the switching process itself is still under debate. Two possible scenarios exist: coherent rotation [4] or domain nucleation and propagation [2]. The critical current densities required for these distinct processes differ by orders of magnitude since for domain driven reversal a much smaller energy barrier needs to be overcome. It is believed that for devices much larger than one domain wall width, the quasi-static switching process is domain driven [2,5,9,15]. However, when reducing the size, it has been demonstrated recently that the switching process can be described by uniform motion [14]. By studying switching probabilities using short current pulses of variable width [3,6,7,14] reliable switching for applied pulse widths as short as 180 ps [6] has been demonstrated. In these experiments, switching dynamics is investigated indirectly by examining the final state long after the current pulse has been applied. To understand the speed and type of the SOT induced switching process in detail, temporal and spatial resolution is required which is met in this Letter using time resolved scanning magneto-optical Kerr micoscopy (TRMOKE).Here we measure the trajectory of...

show abstract

Improvement of the interfacial Dzyaloshinskii-Moriya interaction by introducing a Ta buffer layer

Cited by 62 publications

References 37 publications

Dzyaloshinskii-Moriya Interaction across an Antiferromagnet-Ferromagnet Interface

Dzyaloshinskii-Moriya Interaction across an Antiferromagnet-Ferromagnet Interface

Domain-wall profiles in Co/Irn /Pt(111) ultrathin films: Influence of the Dzyaloshinskii-Moriya interaction

Time Resolved Measurements of the Switching Trajectory of Pt/Co Elements Induced by Spin-Orbit Torques

Contact Info

Product

Resources

About