Jimmy J. Kan

Qualcomm (United States)

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Eric E. Fullerton

University of California, San Diego

Seung H. Kang

Market Matters

M. Gottwald

IBM (United States)

Chando Park

Market Matters

Dylan Lu

University of California, Berkeley

Zhaowei Liu

University of California, San Diego

Kangho Lee

Universität der Bundeswehr München

Chi Ching

Applied Materials (United States)

Mahendra Pakala

Applied Materials (United States)

Keith Chan

Vantage View (United States)

Cooperative Institutions

University of California, San Diego

Digital Research Alliance of Canada

Qualcomm (United States)

IBM (United States)

Beihang University

Lawrence Berkeley National Laboratory

Applied Materials (United States)

Chinese Academy of Sciences

Centre National de la Recherche Scientifique

IBM Research - Thomas J. Watson Research Center

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Ferromagnetic resonance studies of CoFeB-MgO

Bulletin of the American Physical Society (2011)

Erik Shipton Ken Lee Jonathon Sapan Jimmy J. Kan Keith Chan

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Systematic validation of 2x nm diameter perpendicular MTJ arrays and MgO barrier for sub-10 nm embedded STT-MRAM with practically unlimited endurance

2021 IEEE International Electron Devices Meeting (IEDM) (2016)

Jimmy J. Kan Chando Park Chi Ching Jin-Hyun Ahn Xue Lin

We present a comprehensive device and scalability validation of STT-MRAM for high performance applications in sub-10 nm CMOS by providing the first statistical account of barrier reliability in perpendicular magnetic tunnel junctions (pMTJs) from 70 to 25 nm diameter in 1 Gbit arrays. We have experimentally investigated the time-dependent dielectric breakdown (TDDB) properties and the dependence of the pMTJ lifetime on voltage, polarity, duty-cycle, and temperature. A large write-to-breakdown voltage window of > 1 V (> 20 σavg) was measured and a long time-to-breakdown was projected (> 10 ¹⁵ cycles) for 45 nm pMTJs, guaranteeing practically unlimited write cycles. We also reveal a dramatic enhancement of barrier reliability in conjunction with pMTJ size scaling down to 25 nm diameter, further widening the operating window at deeply scaled nodes.

Magnetoresistive random-access memory

Duty cycle

Tunnel magnetoresistance

Dielectric strength

10.1109/iedm.2016.7838493

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Citations (54)

Tunable surface plasmon polaritons in Ag composite films by adding dielectrics or semiconductors

Applied Physics Letters (2011)

Dylan Lu Jimmy J. Kan Eric E. Fullerton Zhaowei Liu

We demonstrate that the surface plasmon polariton (SPP) properties of the silver composite films can be tuned by modest additions of silicon oxide or silicon. The dispersion relations deviate from that of pure silver films, and exhibit the capability to shift the surface plasmon frequency and provide larger SPP wave vectors at longer wavelengths. The effective permittivities are modeled phenomenologically by taking into account both filling ratios and size effects. These types of tunable composite films have various useful applications in areas, such as superlens imaging, SPP based sensing, enhanced photoluminescence, and SPP based photovoltatics.

Nanophotonics

10.1063/1.3600661

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Citations (29)

Geometric Structure of Magnetic Domains in CoPd/IrMn Multilayer Films

Bulletin of the American Physical Society (2011)

Run Su Sujoy Roy Keoki Seu Daniel Parks Jimmy J. Kan

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A statistical study of magnetic tunnel junctions for high-density spin torque transfer-MRAM (STT-MRAM)

R. S. Beach Tai Min C. Horng Q. Chen Phillip Sherman

We have demonstrated a robust magnetic tunnel junction (MTJ) with a resistance-area product RA=8 Ω—μm ² that simultaneously satisfies the statistical requirements of high tunneling magnetoresistance TMR ≫ 15σ(R p ), write threshold spread σ(Vw)/≪Vw≫ ≪7.1%, breakdown-to-write voltage margin over 0.5V, read-induced disturbance rate below 10 ⁻⁹ , and sufficient write endurance, and is free of unwanted write-induced magnetic reversal. The statistics suggest that a 64Mb chip at the 90-nm node is feasible.

Tunnel magnetoresistance

Magnetoresistive random-access memory

Spin-transfer torque

10.1109/iedm.2008.4796679

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Citations (48)

Dynamic switching of the spin circulation in tapered magnetic nanodisks

Nature Nanotechnology (2013)

Vojtěch Uhlíř Michal Urbánek L. Hladík J. Spousta M-Y. Im

Precession

Nanosecond

Polarity (international relations)

Circulation (fluid dynamics)

Geomagnetic reversal

10.1038/nnano.2013.66

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Citations (114)

Paramagnetic Fe_xTa_{1-x} alloys for engineering of perpendicularly magnetized tunnel junctions

arXiv (Cornell University) (2013)

M. Gottwald Jimmy J. Kan Kangho Lee Seung H. Kang Eric E. Fullerton

Exchange coupling between two magnetic layers through an interlayer is of broad interest for numerous recent applications of nano-magnetic systems. In this Letter we study ferromagnetic exchange coupling through amorphous paramagnetic Fe-Ta alloys. We show that the exchange coupling depends exponentially on spacer thickness and scales with the Fe-Ta susceptibility, which can be tuned via the alloy composition and/or temperature. Such materials are of high interest for the engineering of perpendicularly magnetized CoFeB-MgO based tunnel junctions as it enables ferromagnetic coupling of magnetic layers with differing crystalline lattices, suppresses dead layers and can act as an inter-diffusion barrier during annealing.

Tunnel magnetoresistance

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Oriented Growth of Single-Crystal Ni Nanowires onto Amorphous SiO₂

Nano Letters (2010)

Keith Chan Jimmy J. Kan Christopher Doran Lu Ouyang David J. Smith

Highly oriented, single-crystal Ni nanowire arrays have been synthesized atop amorphous SiO2∥Si substrates using a single-step chemical vapor deposition method in the absence of any foreign catalyst. Electron and X-ray diffraction confirm the crystalline quality of the Ni nanowires while magnetoresistance measurements probe the magnetic response and the behavior is explained using simulation results for nanoscale, single-crystal Ni. A growth mechanism involving competing chemical, energetic, and kinetic influences is presented.

Crystal (programming language)

10.1021/nl103301x

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Citations (38)

Ultra-thin Co/Pd multilayers with enhanced high-temperature annealing stability

Applied Physics Letters (2013)

M. Gottwald K. Lee Jimmy J. Kan B. Ocker J. Wrona

Understanding the thermal budget of perpendicular materials is crucial for the potential application perpendicular magnetic tunnel junctions. In this paper, we study the effects of high-temperature rapid thermal annealing on the structural and magnetic properties of ultra-thin Co/Pd multilayers deposited at room temperature. It is shown that perpendicular magnetic anisotropy of ultra-thin Co/Pd multilayers improves with increasing annealing temperature up to 425 °C. This property of ultra-thin Co/Pd multilayers provides increased thermal budgets for CMOS-integrated magnetic devices.

Thermal Stability

10.1063/1.4791577

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Citations (41)

Emergent Rotational Symmetries in Disordered Magnetic Domain Patterns

Physical Review Letters (2011)

Run Su Keoki Seu Daniel Parks Jimmy J. Kan Eric E. Fullerton

Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in CoPd/IrMn heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition.

Metastability

Domain wall (magnetism)

10.1103/physrevlett.107.257204

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Citations (12)