Influence of the magnetic proximity effect on spin-orbit torque efficiencies in ferromagnet/platinum bilayers

Peterson, T. A.; McFadden, Anthony; Palmstrøm, C. J.; Crowell, P. A.

doi:10.1103/physrevb.97.020403

Cited by 30 publications

(18 citation statements)

References 53 publications

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“…For this study, the Co layers were wedges with thickness varying between 0.75 and 1.4 nm for x = 1 and between 0.64 and 0.94 nm for x ≤ 0.75 across the wafer to enable the study of both PMA and IMA Pd 1− x Pt x /Co devices. For Pd 1− x Pt x /Co bilayers, the saturation magnetization ( M s ) varies between 1450 and 1700 emu cm −3 for different x , indicative of an enhancement due to a magnetic proximity effect at the interface, which, however, should not degrade ξ DL as is discussed previously . M s for the Pd 1− x Pt x /Fe 0.6 Co 0.2 B 0.2 bilayers remains almost constant with x , ≈1200 emu cm −3 .…”

Section: Resultssupporting

confidence: 78%

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys

Zhu

Sobotkiewich

et al. 2019

Adv Funct Materials

133

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Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization, spin-orbit torque (SOT) operations are currently energy inefficient due to a low damping-like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials. This work reports an advantageous spin Hall material, Pd 1−x Pt x , which combines a low resistivity with a giant spin Hall effect as evidenced with three independent SOT ferromagnetic detectors. The optimal Pd 0.25 Pt 0.75 alloy has a giant internal spin Hall ratio of >0.60 (damping-like SOT efficiency of ≈0.26 for all three ferromagnets) and a low resistivity of ≈57.5 µΩ cm at a 4 nm thickness. Moreover, it is found that the Dzyaloshinskii-Moriya interaction (DMI), the key ingredient for the manipulation of chiral spin arrangements (e.g., magnetic skyrmions and chiral domain walls), is considerably strong at the Pd 1−x Pt x /Fe 0.6 Co 0.2 B 0.2 interface when compared to that at Ta/Fe 0.6 Co 0.2 B 0.2 or W/Fe 0.6 Co 0.2 B 0.2 interfaces and can be tuned by a factor of 5 through control of the interfacial spin-orbital coupling via the heavy metal composition. This work establishes a very effective spin current generator that combines a notably high energy efficiency with a very strong and tunable DMI for advanced chiral spintronics and spin torque applications.

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Section: Resultssupporting

confidence: 78%

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys

Zhu

Sobotkiewich

et al. 2019

Adv Funct Materials

133

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“…Experimental works, however, seem to confirm the possible Rashba-Edelstein origin of the field. 31,32 Note, that an interfacial contribution might be also attributed to magnetic proximity effect from ferromagnet, 33,34 which was recently discussed by Zhu et al 35 The authors showed that proximity effect in Co/Pt and Au 25 Pt 75 /Co interfaces has minimal correlation on either the dampinglike or the fieldlike spin-orbit torques compared to other interfacial effects like interfacial spin-orbit scattering. The relevant parameters used to modelled of the effective fields are summarized in Table I.…”

Section: Resultsmentioning

confidence: 93%

Field-Free Spin-Orbit-Torque Switching in Co / Pt / Co Multilayer with Mixed Magnetic Anisotropies

et al. 2019

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Spin-orbit-torque (SOT) induced magnetization switching in Co/Pt/Co trilayer, with two Co layers exhibiting magnetization easy axes orthogonal to each other is investigated. Pt layer is used as a source of spin-polarized current as it is characterized by relatively high spin-orbit coupling. The spin Hall angle of Pt, θ = 0.08 is quantitatively determined using spin-orbit torque ferromagnetic resonance technique. In addition, Pt serves as a spacer between two Co layers and depending on it's thickness, different interlayer exchange coupling (IEC) energy between ferromagnets is induced. Intermediate IEC energies, resulting in a top Co magnetization tilted from the perpendicular direction, allows for SOT-induced field-free switching of the top Co layer. The switching process is discussed in more detail, showing the potential of the system for neuromorphic applications.

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“…Earlier studies have shown that the structural properties of the atoms near the FM/NM interface determine the spin-transport properties [17,18]. Furthermore, broken spatial inversion symmetry at the FM-NM interface can be attributed to nonequivalent spin-transport properties (e.g., SOT, iDMI) [19][20][21][22] between NM/FM (FM on top of NM) and FM/NM (NM on top of FM). Earlier studies showed that in symmetric * anil@iisc.ac.in NM/FM/NM systems, SOT and iDMI can prevail due to different structural and/or magnetic properties at the NM/FM and FM/NM interfaces.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric modification of the magnetic proximity effect in Pt/Co/Pt trilayers by the insertion of a Ta buffer layer

et al. 2020

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The magnetic proximity effect in top and bottom Pt layers induced by Co in Ta/Pt/Co/Pt multilayers has been studied by interface-sensitive, element-specific x-ray resonant magnetic reflectivity. The asymmetry ratio for circularly polarized x-rays of left and right helicity has been measured at the Pt L 3 absorption edge (11 567 eV) with an in-plane magnetic field (±158 mT) to verify its magnetic origin. The proximity-induced magnetic moment in the bottom Pt layer decreases with the thickness of the Ta buffer layer. Grazing incidence x-ray diffraction has been carried out to show that the Ta buffer layer induces the growth of Pt(011) rather than Pt(111), which in turn reduces the induced moment. A detailed density functional theory study shows that an adjacent Co layer induces more magnetic moments in Pt(111) than in Pt(011). The manipulation of the magnetism in Pt by the insertion of a Ta buffer layer provides a way to control the magnetic proximity effect, which is of huge importance in spin-transport experiments across similar kinds of interfaces.

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Influence of the magnetic proximity effect on spin-orbit torque efficiencies in ferromagnet/platinum bilayers

Cited by 30 publications

References 53 publications

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys

Field-Free Spin-Orbit-Torque Switching in Co / Pt / Co Multilayer with Mixed Magnetic Anisotropies

Asymmetric modification of the magnetic proximity effect in Pt/Co/Pt trilayers by the insertion of a Ta buffer layer

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Influence of the magnetic proximity effect on spin-orbit torque efficiencies in ferromagnet/platinum bilayers

Cited by 30 publications

References 53 publications

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd1−xPtx Alloys

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd1−xPtx Alloys

Field-Free Spin-Orbit-Torque Switching in Co / Pt / Co Multilayer with Mixed Magnetic Anisotropies

Asymmetric modification of the magnetic proximity effect in Pt/Co/Pt trilayers by the insertion of a Ta buffer layer

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Product

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Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys

Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd₁₋_xPt_x Alloys