Variation of the giant intrinsic spin Hall conductivity of Pt with carrier lifetime

Zhu, Lijun; Zhu, Lujun; Sui, Manling; Ralph, Daniel; Buhrman, R. A.

doi:10.1126/sciadv.aav8025

Cited by 90 publications

(114 citation statements)

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“…Sample series A1-A6, B1-B3, and C1 (Table 1) were patterned into magnetic strips (10×20 μm 2 ) via photolithography and ion milling to measure α and the effective demagnetization field (4πM eff ) and the SOT efficiencies using spin-torque ferromagnetic resonance (ST-FMR) [24,25] and also into Hall bars (5 × 65 μm 2 ) for determination of SOT efficiencies using "in-plane" harmonic Hall response technique [26][27][28]. α and 4πM eff of sample series B4 and C2-C6 (Table 1) were obtained from unpatterned pieces using a flip-chip FMR with the magnetic pieces face-side down on a co-plane waveguide.…”

Section: Sample Configurationsmentioning

confidence: 99%

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Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Zhu

Ralph

et al. 2020

Phys. Rev. Applied

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We experimentally investigate the origin of the two-magnon scattering (TMS) in heavy-metal (HM)/ferromagnet (FM)/oxide heterostructures (FM = Co, Ni 81 Fe 19 , or Fe 60 Co 20 B 20 ) by varying the materials located above and below the FM layers. We show that strong TMS in HM/FM/oxide systems arises primarily at the HM/FM interface and increases with the strength of interfacial spin-orbit coupling and magnetic roughness at this interface. TMS at the FM/oxide interface is relatively weak, even in systems where spin-orbit coupling at this interface generates strong interfacial magnetic anisotropy. We also suggest that the spin-current-induced excitation of non-uniform short-wavelength magnon at the HM/FM interface may function as a mechanism of spin memory loss for the spin-orbit torque exerted on the uniform mode.

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Section: Sample Configurationsmentioning

confidence: 99%

“…6(b), DL E was estimated from the ST-FMR measurement to be (0.98 ± 0.03)×10 5 Ω -1 m -1 for Co/Pt (A1), to (1.62 ± 0.04)×10 5 As described in more detail in Refs. [27,28], the cosφ…”

Section: Influence Of Short-wavelength Magnons On Spin Torquementioning

confidence: 99%

Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Zhu

Ralph

et al. 2020

Phys. Rev. Applied

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“…Meanwhile, the shared read/write path can lead to write upon read errors. In a SOT-MRAM, the spin current generated by the spin Hall effect (SHE) [10][11][12][13] of a heavy metal layer switches the magnetic free layer of a MTJ (see Figure 1a). In a SOT-MRAM, the spin current generated by the spin Hall effect (SHE) [10][11][12][13] of a heavy metal layer switches the magnetic free layer of a MTJ (see Figure 1a).…”

Section: Energy-efficient Ultrafast Sot-mrams Based Onmentioning

confidence: 99%

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75

Zhu

Shi

et al. 2020

Adv Elect Materials

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As shown in Figure 1b-d, the SOT-MTJ devices were lithographically patterned from sputter-deposited multilayer stacks consisting of Si/SiO 2 /Ta 1/Au 0.25 Pt 0.75 5/Hf 0.5/ Fe 0.6 Co 0.2 B 0.2Many key electronic technologies (e.g., large-scale computing, machine learning, and superconducting electronics) require new memories that are at the same time fast, reliable, energy-efficient, and of low-impedance, which has remained a challenge. Nonvolatile magnetoresistive random access memories (MRAMs) driven by spin-orbit torques (SOTs) have promise to be faster and more energy-efficient than conventional semiconductor and spin-transfer-torque magnetic memories. It is reported that the spin Hall effect of low-resistivity Au 0.25 Pt 0.75 thin films enables ultrafast antidamping-torque switching of SOT-MRAM devices for current pulse widths as short as 200 ps. If combined with industrial-quality lithography and already-demonstrated interfacial engineering, an optimized MRAM cell based on Au 0.25 Pt 0.75 can have energy-efficient, ultrafast, and reliable switching, for example, a write energy of <1 fJ (<50 fJ) for write error rate of 50% (<10 −5 ) for 1 ns pulses. The antidamping torque switching of the Au 0.25 Pt 0.75 devices is ten times faster than expected from a rigid macrospin model, most likely because of the fast micromagnetics due to the enhanced nonuniformity within the free layer. The feasibility of Au 0.25 Pt 0.75 -based SOT-MRAMs as a candidate for ultrafast, reliable, energy-efficient, low-impedance, and unlimited-endurance memory is demonstrated.

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“…Since and are fixed, the nonmonotonic x dependence of SOT efficiency inFig. 2(b)can be interpreted by the change in and apparent spin Hall conductivity ( * = ) 16,34. Fig.…”

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confidence: 97%

Spin Hall magnetoresistance sensor using AuxPt1−x as the spin-orbit torque biasing layer

Yang

Xie

et al. 2019

Applied Physics Letters

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We report on investigation of spin Hall magnetoresistance sensor based on NiFe/ AuxPt1-x bilayers. Compared to NiFe/Pt, the NiFe/AuxPt1-x sensor exhibits a much lower power consumption (reduced by about 57%), due to 80% enhancement of spin-orbit torque efficiency of AuxPt1-x at an optimum composition of x = 0.19 as compared to pure Pt. The enhanced spin-orbit torque efficiency allows to increase the thickness of NiFe from 1.8 nm to 2.5 nm without significantly increasing the power consumption.We show that, by increasing the NiFe thickness, we were able to improve the working field range (± 0.86 Oe), operation temperature range (150 o C) and detectivity (0.71 nT/√Hz at 1 Hz) of the sensor, which is important for practical applications.In the past few decades, a variety of magnetoresistance (MR) sensors have been developed and commercialized for diverse industrial and consumer applications, 1-6 including in the rapidly developing internet-of-things (IoT) paradigm and related technologies. 7 These include the anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR) and tunnel magnetoresistance (TMR) sensors. 1,8-10 All these sensors require sophisticated transverse biasing scheme for achieving linear response to an external field. 11 Recently we have demonstrated a spin Hall magnetoresistance (SMR) sensor using spin orbit torque (SOT) induced field-like effective field as the built-in linearization mechanism. 12,13 The use of SOT biasing greatly simplifies the sensor design, which consists of only a NiFe/Pt bilayer. 11 Furthermore, since the SMR is a second order effect, it allows to drive the sensor by an ac current and detect the response using the rectification technique. The combination of all these features has led to a SMR sensor with nearly zero dc offset and negligible hysteresis, and a detectivity around 1 nT/ √Hz at 1 Hz. 14 The performance is remarkable considering its extremely simple structure. However, in order to obtain a large field-like SOT effective field, in the previous studies, the NiFe layer thickness has been optimized to be around 1.8 nm. Such a small thickness of NiFe limits both the sensor's working field (±0.35 Oe) and operation temperature range (80 ⁰C), which may hinder practical application of the SMR sensor. Both issues, however, could be readily resolved if we can have a spin current and SOT generator which is more efficient than Pt and at the same time has a relatively low resistivity.Recently, several works have reported that alloying Pt with Au is an effective way to increase the SOT efficiency through enhancing the intrinsic spin Hall effect, 15,16 while the resistivity of AuxPt1-x alloy is still much lower than that of β-W, 17 β-Ta, 18 Pt-Hf alloy, 19 Pt/Hf multilayers 20 and topological insulators; 21,22 the latter is important for low-power operation of the sensor. In this work, we examine the possibility of using AuxPt1-x alloy to improve the working field and operation temperature range of the SMR sensors. Specifically, we fabricated

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Variation of the giant intrinsic spin Hall conductivity of Pt with carrier lifetime

Cited by 90 publications

References 50 publications

Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75

Spin Hall magnetoresistance sensor using AuxPt1−x as the spin-orbit torque biasing layer

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Variation of the giant intrinsic spin Hall conductivity of Pt with carrier lifetime

Cited by 90 publications

References 50 publications

Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Origin of Strong Two-Magnon Scattering in Heavy-Metal/Ferromagnet/Oxide Heterostructures

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au0.25Pt0.75

Spin Hall magnetoresistance sensor using AuxPt1−x as the spin-orbit torque biasing layer

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Product

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Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75