San Jose Research Center

San Jose, CA, United States

San Jose Research Center

San Jose, CA, United States
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Marchon B.,San Jose Research Center | Saito Y.,Hitachi Ltd.
IEEE Transactions on Magnetics | Year: 2012

Molecular dynamics modeling of lubricant displacement on a disk during transient heating in a heat assisted recording interface is presented. It is found that in the time and dimension scales expected for high density recording (nanosecond, tens of nanometers), a significant lubricant removal from the heat spot center can occur, leading to the formation of a rim around it. Continuum fluid dynamics calculations were also performed using a temperature dependent Hamaker constant for lubricant-lubricant interactions. These results were in good agreement with the molecular dynamics predictions. © 2012 IEEE.

Wurmehl S.,Leibniz Institute for Solid State and Materials Research | Jacobs P.J.,TU Eindhoven | Kohlhepp J.T.,TU Eindhoven | Swagten H.J.M.,TU Eindhoven | And 4 more authors.
Applied Physics Letters | Year: 2011

We systematically study the changes in the local atomic environments of Co in CoFe-Al alloys as a function of Al content by means of nuclear magnetic resonance. We find that a Co2 FeAl Heusler type structure is formed on a local scale. The observed formation of a highly spin-polarized Heusler compound may explain the improved magnetotransport properties in CoFe-Al based current-perpendicular-to-the-plane spin-valves. © 2011 American Institute of Physics.

Pfau B.,TU Berlin | Pfau B.,Helmholtz Center Berlin | Gunther C.M.,TU Berlin | Gunther C.M.,Helmholtz Center Berlin | And 7 more authors.
Optics Express | Year: 2010

We present a method for high-resolution magnetic imaging at linearly polarized partially coherent x-ray sources. The magnetic imaging was realized via Fourier transform holography. In order to achieve elliptical x-ray polarization, three different filters were designed based on the x-ray magnetic circular dichroism effect. We present proof-of-principle images of magnetic nanostructures and discuss the application of the method for future experiments at free-electron laser sources. © 2010 Optical Society of America.

Marchon B.,San Jose Research Center | Saito K.,San Jose Research Center | Wilson B.,San Jose Research Center | Wood R.,San Jose Research Center
IEEE Transactions on Magnetics | Year: 2011

This paper discusses the validity of the Triple Harmonic method and the Wallace readback model for the determination of head-disk spacing variations in today's perpendicular recording (PMR) systems at >500 Gb/in2 areal density. For the recording system investigated here, and in the limit of high frequency, approximately beyond the frequency corresponding to the 2 T (0011) pattern, this method fails, as head and electronic noise start to interfere. In the low-frequency range of PMR systems, the Wallace equation does not apply any longer. Accurate magnetic spacing variations can be obtained by using the FFT of the intensity ratio of the readback signals, and fitting with the appropriate algebraic expression. Using this method, a repeatability of less than 0.1 nm was obtained, by using a random data pattern of only four 512 bytes data sector long. © 2011 IEEE.

Liu H.,New York University | Bedau D.,New York University | Sun J.Z.,IBM | Mangin S.,CNRS Jean Lamour Institute | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We present a two-current-pulse temporal correlation experiment to study the intrinsic subnanosecond nonequilibrium magnetic dynamics of a nanomagnet during and following a pulse excitation. This method is applied to a model spin-transfer system, a spin-valve nanopillar with perpendicular magnetic anisotropy. Two pulses separated by a short delay (<500 ps) are shown to lead to the same switching probability as a single pulse with a duration that depends on the delay. This demonstrates a remarkable symmetry between magnetic excitation and relaxation and provides a direct measurement of the magnetic relaxation time. The results are consistent with a simple finite-temperature Fokker-Planck macrospin model of the dynamics, suggesting more coherent magnetization dynamics in this short-time nonequilibrium limit than near equilibrium. © 2012 American Physical Society.

Liu H.,New York University | Bedau D.,New York University | Backes D.,New York University | Katine J.A.,San Jose Research Center | And 2 more authors.
Applied Physics Letters | Year: 2010

Orthogonal spin-transfer magnetic random access memory (OST-MRAM) uses a spin-polarizing layer magnetized perpendicularly to a free layer to achieve large spin-transfer torques and ultrafast energy efficient switching. We have fabricated and studied OST-MRAM devices that incorporate a perpendicularly magnetized spin-polarizing layer and a magnetic tunnel junction, which consists of an in-plane magnetized free layer and synthetic antiferromagnetic reference layer. Reliable switching is observed at room temperature with 0.7 V amplitude pulses of 500 ps duration. The switching is bipolar, occurring for positive and negative polarity pulses, consistent with a precessional reversal mechanism, and requires an energy of less than 450 fJ. © 2010 American Institute of Physics.

Gopman D.B.,New York University | Bedau D.,New York University | Mangin S.,CNRS Jean Lamour Institute | Lambert C.H.,CNRS Jean Lamour Institute | And 3 more authors.
Applied Physics Letters | Year: 2012

We report the free layer switching field distributions of spin-valve nanopillars with perpendicular magnetization. While the distributions are consistent with a thermal activation model, they show a strong asymmetry between the parallel to antiparallel and the reverse transition, with energy barriers more than 50 higher for the parallel to antiparallel transitions. The inhomogeneous dipolar field from the polarizer is demonstrated to be at the origin of this symmetry breaking. Interestingly, the symmetry is restored for devices with a lithographically defined notch pair removed from the midpoint of the pillar cross-section along the ellipse long axis. These results have important implications for the thermal stability of perpendicular magnetized magnetic random access memory bit cells. © 2012 American Institute of Physics.

Bedau D.,New York University | Liu H.,New York University | Sun J.Z.,IBM | Katine J.A.,San Jose Research Center | And 3 more authors.
Applied Physics Letters | Year: 2010

The effect of thermal fluctuations on spin-transfer switching has been studied for a broad range of time scales (subnanoseconds to seconds) in a model system, a uniaxial thin film nanomagnet. The nanomagnet is incorporated into a spin-valve nanopillar, which is subject to spin-polarized current pulses of variable amplitude and duration. Two physical regimes are clearly distinguished: a long pulse duration regime, in which reversal occurs by spin-transfer assisted thermal activation over an energy barrier, and a short-time large pulse amplitude regime, in which the switching probability is determined by the spin-angular momentum in the current pulse. © 2010 American Institute of Physics.

Bedau D.,New York University | Liu H.,New York University | Bouzaglou J.-J.,New York University | Bouzaglou J.-J.,CNRS Jean Lamour Institute | And 5 more authors.
Applied Physics Letters | Year: 2010

Spin-transfer switching with short current pulses has been studied in spin-valve nanopillars with perpendicularly magnetized free and reference layers. Magnetization switching with current pulses as short as 300 ps is demonstrated. The pulse amplitude needed to reverse the magnetization is shown to be inversely proportional to the pulse duration, consistent with a macrospin spin-transfer model. However, the pulse amplitude duration switching boundary depends on the applied field much more strongly than predicted by the zero temperature macrospin model. The results also demonstrate that there is an optimal pulse length that minimizes the energy required to reverse the magnetization. © 2010 American Institute of Physics.

Home > Press > Leti IEDM 2016 Paper Clarifies Correlation between Endurance, Window Margin and Retention in RRAM for First Time: Paper Presented at IEDM 2016 Offers Ways to Reconcile High-cycling Requirements and Instability at High Temperatures in Resistive RAM Abstract: A Leti research project presented at IEDM 2016 today clarified for the first time the correlation between endurance, window margin and retention of resistive RAM (RRAM), a non-volatile random-access memory. RRAM devices are strong candidates to replace Flash for both stand-alone storage applications and embedded products, because of their high density, high speed, good endurance and integration in the BEOL. But combining key features such as sufficient cycling and stable retention at high temperature has proven to be a major challenge for memory makers. Current RRAM thinking holds that a high number of write-and-erase sequences (cycles) leads to poor temperature stability. The paper presented at IEDM, “Understanding the Trade-off in Terms of Endurance, Retention and Window Margin of RRAM Using Experimental Results and Simulations”, explains how these three memory characteristics are linked and how to modulate them depending on the material and the programming conditions used. “In this work, we demonstrated how physics rule memory features and performances,” said Luca Perniola, head of Leti’s memory component lab. “Universal behaviors and tradeoffs are clearly identified, putting boundaries on the best memories tailored for various specific applications.” Investigating various classes of RRAM, such as OXRAM and CBRAM, the project determined that best performance in each category was achieved with different RRAM, resulting in stability in temperature up to 300°C, as well as a window margin up to 1,000 and endurance up to 109 cycles. Exploring the different materials’ ability to allow many cycles with strong temperature stability, the team identified three correlated parameters that influence performance: the number of cycles RRAM can reach, the stability in temperature and the ratio between the two states of the memory. Thus, by playing with the material stack, researchers were able to address various non-volatile memory applications, targeting high speed, high endurance or high stability. The team simulated four different RRAM active materials at the atomic level to extract parameters that could explain the link between material and performance and identify the species responsible for the switching mechanism between the two memory states. It also proposed an analytical model to link the memory characteristics and the material parameters extracted from atomistic simulation. The biggest step was the fabrication on a 1T1R base wafer of one of the four RRAM, showing high endurance and high window margin, which was rare in the research literature. Leti, which offers the significant advantage of combining device fabrication, electrical characterization and modeling, from ab initio calculations to device modeling, and design, led the research. Its partners included MEP LAHC CNRS and LTM CNRS of Grenoble, and the WD San Jose Research Center. About Leti As one of three advanced-research institutes within the CEA Technological Research Division, Leti serves as a bridge between basic research and production of micro- and nanotechnologies that improve the lives of people around the world. It is committed to creating innovation and transferring it to industry. Backed by its portfolio of 2,800 patents, Leti partners with large industrials, SMEs and startups to tailor advanced solutions that strengthen their competitive positions. It has launched 59 startups. Its 8,500m² of new-generation cleanroom space feature 200mm and 300mm wafer processing of micro and nano solutions for applications ranging from space to smart devices. With a staff of more than 1,900, Leti is based in Grenoble, France, and has offices in Silicon Valley, Calif., and Tokyo. Follow us on and @CEA_Leti. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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