Characterization and Manipulation of Spin Orbit Torque in Magnetic Heterostructures

Qiu, Xuepeng; Shi, Zhong; Wang, Fan; Zhou, Shiming; Yang, Hyunsoo

doi:10.1002/adma.201705699

Cited by 105 publications

(55 citation statements)

References 111 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The parameters of a model included layer thickness, interface (or surface) roughness and ESLD. Errors reported for parameters obtained from XRR measurements represent the perturbation of a parameter that increased goodness of fit parameter corresponds to a 2σ error (95% confidence) [15]. (d-f) Electron scattering length density depth profiles for corresponding single layer and bilayer, which best fitted XRR data.…”

Section: X-ray and Polarized Neutron Reflectivitymentioning

confidence: 99%

“…The Dzyaloshinskii-Moriya interaction [6], and the spin Hall effect via heavy-metal layers [7-9] were the major phenomena that attributed for large chiral spin torques. Exchange coupling torque (ECT) recently showed a significant enhancement of the spin-torque efficiency in artificial antiferromagnetic (AF) structures [10,11], which allows moving nanoscale magnetic domain walls (DW) with current at large velocities [10].The compensated rare earth (RE)-transition metal (TM) alloys and heterostructures,where the RE and TM moments are aligned antiparallel due to the strong AF interaction and the total net moment tends to zero, are potential candidate materials for realizing devices with higher speed and density [12][13][14][15][16]. A class of ferrimagnets consisting of RE-TM alloys and heterostructures also have the potential to exhibit DW motion via an ECT [17,18].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Antisymmetric magnetoresistance and helical magnetic structure in a compensated Gd/Co multilayer

et al. 2019

View full text Add to dashboard Cite

Using spin dependent specular and off-specular polarized neutron reflectivity (PNR), we report the observation of a twisted helical magnetic structure with planar 2π domain wall (DW) and highly correlated magnetic domains in a Gd/Co multilayer. Specular PNR with polarization analysis reveals the formation of planar 2πDWs below a compensation temperature (T Comp ), resulting to positive exchange bias in this system. Off-specular PNR with spin polarization showed development of magnetic inhomogenities (increase in magnetic roughness) for central part (thickness ~ 25-30 Å) of each Gd layer, where magnetization is aligned perpendicular (in-plane) to an applied field. These magnetic roughness are vertically correlated and results into Bragg sheet in spin flip channel of Offspecular PNR data, which is contributing towards an antisymmetric magnetoresistance at T Comp in the system. The growth and tunability of highly correlated magnetic inhomogeneities (roughness) and domain structure around T Comp in combination of twisted helical magnetic structure with planar 2πDWs will be key for application in all-spin-based technology.The current-induced manipulation of magnetic order through spin-orbit torque (SOT) has recently attracted great interest for the realization of magnetic memory and logic application devices with fast switching [1][2][3][4][5]. The Dzyaloshinskii-Moriya interaction [6], and the spin Hall effect via heavy-metal layers [7-9] were the major phenomena that attributed for large chiral spin torques. Exchange coupling torque (ECT) recently showed a significant enhancement of the spin-torque efficiency in artificial antiferromagnetic (AF) structures [10,11], which allows moving nanoscale magnetic domain walls (DW) with current at large velocities [10].The compensated rare earth (RE)-transition metal (TM) alloys and heterostructures,where the RE and TM moments are aligned antiparallel due to the strong AF interaction and the total net moment tends to zero, are potential candidate materials for realizing devices with higher speed and density [12][13][14][15][16]. A class of ferrimagnets consisting of RE-TM alloys and heterostructures also have the potential to exhibit DW motion via an ECT [17,18]. Fast switching in compensated systems can further be influenced by magnetic [16,19] and optical [20] fields. Recently Vedmedenko et al. [21], have pointed out theoretically that nano-sized stable magnetic helices can be used for magnetic energy storage. Realization of magnetic helices with stable magnetic properties have also been studied theoretically [22] and experimentally [23] in exchange-coupled thin films and RE/TM multilayers, respectively. It is recognized that magnetization reversal and a magnetic helical configuration (planar 2πDWs) in RE-TM multilayer with no external magnetic field around the compensation temperature (T Comp , the temperature at which total moments of RE-TM multilayer tend to zero) is the key to manipulating magnetic devices [20,23]. However the response of interface DWs in RE-TM heterostr...

show abstract

Section: X-ray and Polarized Neutron Reflectivitymentioning

confidence: 99%

mentioning

confidence: 99%

Antisymmetric magnetoresistance and helical magnetic structure in a compensated Gd/Co multilayer

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Controlling the spin of electrons effectively and precisely is the core of spintronics which can realize fast-response-speed, low-energy-loss, non-volatile spintronic devices. Subsequently, the discovery of tunnel magnetoresistance, spin transfer torque and spin orbit torque further motivated the rapid development of spintronics [3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Noncollinear spintronics and electric-field control: a review

et al. 2019

View full text Add to dashboard Cite

Our world is composed of various materials with different structures, where spin structures have been playing a pivotal role in spintronic devices of the contemporary information technology. Apart from conventional collinear spin materials such as collinear ferromagnets and collinear antiferromagnetically coupled materials, noncollinear spintronic materials have emerged as hot spots of research attention owing to exotic physical phenomena.In this Review, we firstly introduce two types noncollinear spin structures, i.e., the chiral spin structure that yields real-space Berry phases and the coplanar noncollinear spin structure that could generate momentum-space Berry phases, and then move to relevant novel physical phenomena including topological Hall effect, anomalous Hall effect, multiferroic, Weyl fermions, spin-polarized current, and spin Hall effect without spin-orbit coupling in these noncollinear spin systems. Afterwards, we summarize and elaborate the electric-field control of the noncollinear spin structure and related physical effects, which could enable ultralow power spintronic devices in future. In the final outlook part, we emphasize the importance and possible routes for experimentally detecting the intriguing theoretically predicted spin-polarized current, verifying the spin Hall effect in the absence of spin-orbit coupling and exploring the anisotropic magnetoresistance and domain-wall-related magnetoresistance effects for noncollinear antiferromagnetic materials.

show abstract

“…[3,[24][25][26][27] Figure 2 shows the first (V 1ω ) and second (V 2ω ) harmonic Hall voltages as a function of the in-plane magnetic fields (B x or B y ) for the CoFeB and NiFe samples with various Ta thicknesses. [3,[24][25][26][27] Figure 2 shows the first (V 1ω ) and second (V 2ω ) harmonic Hall voltages as a function of the in-plane magnetic fields (B x or B y ) for the CoFeB and NiFe samples with various Ta thicknesses.…”

Section: Introductionmentioning

confidence: 99%

Material and Thickness Investigation in Ferromagnet/Ta/CoFeB Trilayers for Enhancement of Spin–Orbit Torque and Field‐Free Switching

Ryu

Kang

et al. 2019

Adv Elect Materials

View full text Add to dashboard Cite

in-plane (perpendicular) magnetic anisotropy. The spin current generated from the FM/Ti interface has a spin polarization along the m × y direction, where m is the magnetization direction of the bottom FM. For an FM with m aligned in the x-direction, a spin current with zspin polarization is generated. [22,23] This enables field-free SOT switching of the perpendicular magnetization of the top CoFeB layer.In this work, we investigate the SOTs in FM/Ta/CoFeB trilayers, in which the spin current generated by SHE in Ta can be combined with the interface-generated spin currents. Using various Ta thickness, we perform measurements of SOTinduced effective fields and of magnetization switching with various Ta thicknesses. We observe two interesting points for a sample with a thin Ta layer; first, the sign of the SOT is determined by the bottom FM layer, and is positive for NiFe and negative for CoFeB. Second, SOT-induced switching is achieved without an in-plane magnetic field. These results demonstrate that the interface-generated spin current of the FM/Ta bilayer governs the SOT of a sample with a thin Ta layer. On the other hand, as Ta thickness increases, the sign of the SOT becomes negative irrespective of the bottom FM and which is determined by the Ta, which has a negative spin Hall angle. This demonstrates that the SOT in the trilayer structure is composed of two contributions: SHE in HM and interface-generated spin current of the FM/HM bilayer, suggesting that the proper selection of an FM/HM combination and of the material thickness can enhance the SOT efficiency and induce field-free SOT switching. Results and Discussion Spin-Orbit Torques in FM/Ta/CoFeB TrilayersIn order to investigate SOT in FM/Ta/CoFeB trilayer structures, we employ Ta (5 nm)/FM (4 nm)/Ta (t Ta )/CoFeB (1.0 nm)/ MgO (3.2 nm) structures, where Ta thickness (t Ta ) ranges from 1.0 to 6.0 nm (Figure 1a). The bottom FM is in-plane magnetized CoFeB or NiFe. As the samples share identical material structures, except for the bottom FM, we refer to the trilayer CoFeB or NiFe samples according to the bottom FM layers. We first check the magnetic anisotropy of each layer by Spin-orbit torques (SOTs) in ferromagnet (FM)/Ta/CoFeB trilayers are investigated as a function of Ta thickness. When the Ta is thinner than 1.5 nm, the sign of the SOT exerting on the top perpendicularly magnetized CoFeB depends on the bottom FM layer; it is positive for NiFe and negative for CoFeB. As the Ta thickness increases, the sign becomes negative irrespective of the bottom FM, indicating that SOTs are dominated by Ta, which has a negative spin Hall angle. SOT-induced switching without an in-plane magnetic field is observed in the thickness ranges where the bottom FM or FM/Ta interface-generated SOT is dominant. The results herein demonstrate that proper design of an FM/heavy metal combination and the material thickness can lead to an enhancement of the SOT efficiency and allow for field-free SOT switching.

show abstract

Characterization and Manipulation of Spin Orbit Torque in Magnetic Heterostructures

Cited by 105 publications

References 111 publications

Antisymmetric magnetoresistance and helical magnetic structure in a compensated Gd/Co multilayer

Antisymmetric magnetoresistance and helical magnetic structure in a compensated Gd/Co multilayer

Noncollinear spintronics and electric-field control: a review

Material and Thickness Investigation in Ferromagnet/Ta/CoFeB Trilayers for Enhancement of Spin–Orbit Torque and Field‐Free Switching

Contact Info

Product

Resources

About