Zero-Field Spin Torque Oscillator Based on Magnetic Tunnel Junctions with a Tilted CoFeB Free Layer

Skowroński, Witold; Stobiecki, T.; Wrona, Jerzy; Reiss, Günter; Dijken, Sebastiaan van

doi:10.1143/apex.5.063005

Cited by 38 publications

(41 citation statements)

References 24 publications

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“…11 However, thicker MTJs with interfacial perpendicular anisotropy may exhibit largeamplitude oscillations as well. 12 A similar effect has been observed in single asymmetric (two electrodes are made of different materials) in-plane magnetized 13,14 and double in-plane but noncollinearly magnetized metallic spin valves. 15 Out-of-plane oscillations occur also in specially designed symmetric spin valves with two strongly coupled free layers, 16 asymmetric single spin valves with interfacial perpendicular anisotropy, 17 or standard symmetric and in-plane magnetized valves, although then magnetic fields have to be applied.…”

Section: Introductionsupporting

confidence: 57%

Thermally induced dynamics in ultrathin magnetic tunnel junctions

2013

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We consider the magnetization dynamics induced by thermally induced spin transfer torques in thin Fe|MgO|Fe tunnel junctions. The magnetization dynamics is described by the Landau-Lifshitz-Gilbert equation, including the thermal torques as computed from first principles. We show that the angular skewness of the torques importantly modifies the dynamics, e.g., leading to different instability criteria.

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Section: Introductionsupporting

confidence: 57%

Thermally induced dynamics in ultrathin magnetic tunnel junctions

2013

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“…For microwave generation in the absence of external magnetic fields, various other solutions have been recently proposed. For example, the idea based on a wave-like angular dependence of the spin torque16, the incorporation of a perpendicular polarizer into spin-valve structures17, magnetic vortex oscillations618 or a tilted free layer19, but the resulting microwave power in those STNOs is smaller (<1 nW) and the excitation current is higher (>106 A/cm 2 )11161718. When compared with the best results obtained from previous field-free STNOs, the data in this work show microwave emission with output power at least one order of magnitude larger and critical current densities one order of magnitude smaller.…”

Section: Discussionmentioning

confidence: 99%

Ultralow-current-density and bias-field-free spin-transfer nano-oscillator

Zeng

Finocchio

Zhang

et al. 2013

Sci Rep

178

160

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The spin-transfer nano-oscillator (STNO) offers the possibility of using the transfer of spin angular momentum via spin-polarized currents to generate microwave signals. However, at present STNO microwave emission mainly relies on both large drive currents and external magnetic fields. These issues hinder the implementation of STNOs for practical applications in terms of power dissipation and size. Here, we report microwave measurements on STNOs built with MgO-based magnetic tunnel junctions having a planar polarizer and a perpendicular free layer, where microwave emission with large output power, excited at ultralow current densities, and in the absence of any bias magnetic fields is observed. The measured critical current density is over one order of magnitude smaller than previously reported. These results suggest the possibility of improved integration of STNOs with complementary metal-oxide-semiconductor technology, and could represent a new route for the development of the next-generation of on-chip oscillators.

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“…2,3 Moreover, STT is utilized in MTJ nano-oscillators that generate signals in the GHz frequency range. [4][5][6] In order to optimize MTJ parameters, so that they can compete with existing memory and microwave technologies, it is necessary to fully understand STT. The spin-torque diode effect enables quantitative measurements of STT parameters.…”

Section: Introductionmentioning

confidence: 99%

Influence of MgO tunnel barrier thickness on spin-transfer ferromagnetic resonance and torque in magnetic tunnel junctions

et al. 2013

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Spin-transfer ferromagnetic resonance (ST-FMR) in symmetric magnetic tunnel junctions (MTJs) with a varied thickness of the MgO tunnel barrier (0.75 nm < tMgO < 1.05 nm) is studied using the spin-torque diode effect. The application of an RF current into nanosized MTJs generates a DC mixing voltage across the device when the frequency is in resonance with the resistance oscillations arising from the spin transfer torque. Magnetization precession in the free and reference layers of the MTJs is analyzed by comparing ST-FMR signals with macrospin and micromagnetic simulations. From ST-FMR spectra at different DC bias voltage, the in-plane and perpendicular torkances are derived. The experiments and free-electron model calculations show that the absolute torque values are independent of tunnel barrier thickness. The influence of coupling between the free and reference layer of the MTJs on the ST-FMR signals and the derived torkances are discussed.

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Zero-Field Spin Torque Oscillator Based on Magnetic Tunnel Junctions with a Tilted CoFeB Free Layer

Cited by 38 publications

References 24 publications

Thermally induced dynamics in ultrathin magnetic tunnel junctions

Thermally induced dynamics in ultrathin magnetic tunnel junctions

Ultralow-current-density and bias-field-free spin-transfer nano-oscillator

Influence of MgO tunnel barrier thickness on spin-transfer ferromagnetic resonance and torque in magnetic tunnel junctions

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