Magnetic Recording Heads

Heidmann, J.; Taratorin, Alexander M.

doi:10.1016/b978-0-444-53780-5.00001-6

Cited by 3 publications

(2 citation statements)

References 156 publications

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“…The change in the relative orientation between the FL and PL magnetizations translates into variations in the sensor's tunnel magnetoresistance (TMR), which indicate the difference between the "up" and "down" bits representing the recorded information [1,2]. MTJs are nonlinear dynamic systems.…”

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confidence: 99%

Injection Locking at Fractional Frequencies of Magnetic-Tunnel-Junction-Based Read Sensors’ Ferromagnetic Resonance Modes

et al. 2019

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Being nonlinear dynamic systems, magnetic read sensors should respond to an excitation signal of a frequency considerably different from their natural ferromagnetic resonance (FMR) frequencies.Because of the magnetization dynamics' inherent nonlinear nature, the sensors' response should be measured at the DC, excitation frequency, and its multiples (harmonics). In this paper, we present results of such measurements, accomplished using a one-port nonlinear vector network analyzer (NVNA), which show distinct resonances at fractional frequencies of the free layer (FL) FMR mode.Identification of these resonances, resulting from the nonlinear nature of the spin-torque (ST)induced magnetization dynamics, was performed using micromagnetic modeling. In particular, we show that the measured DC response at the above-mentioned fractional frequencies can be explained by a low-order nonlinearity and strong magnetodipolar feedback between magnetic layers adjacent to an MgO barrier. Additionally, we determined that the simulated harmonic response is strongly enhanced by the mutual ST effect between these layers. Finally, we demonstrate that the read sensors' nonlinear magnetization dynamics and, by extension, their harmonic response are highly sensitive to various magnetic and ST parameters. Thus, this study shows that using NVNA measurements in conjunction with micromagnetic modeling can clarify the uncertainty in the definition of these parameters.

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confidence: 99%

Injection Locking at Fractional Frequencies of Magnetic-Tunnel-Junction-Based Read Sensors’ Ferromagnetic Resonance Modes

et al. 2019

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“…Magnetic nanoparticles (MP) exhibit enhanced magnetic, optical, and electrical properties when compared with their bulk counterparts rendering nanoparticles of interest for a variety of applications information storage [1,2], color imaging [3], magnetic refrigeration [4], ferro-fluids [5], cell sorting [6], medical diagnosis [7], and controlled drug delivery [8]. Most of these applications require chemically stable, well-dispersed and uniform size particles.…”

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confidence: 99%

Fabrication and characterization of dendrimer-encapsulated monometallic Co nanoparticles

Kavas

Durmuș

Tanriverdi

et al. 2011

Journal of Alloys and Compounds

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Magnetic energy flow imaging of magnetic recording head with enhanced resolution and sensitivity by A-MFM using high magnetic moment superparamagnetic tip

Kumar

Cao

Suzuki

et al. 2018

Journal of Applied Physics

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In this report, the magnetic energy flow of AC magnetic field is imaged from a perpendicular magnetic recording head by alternating magnetic force microscopy (A-MFM) with high magnetic moment Co0.43(GdOx)0.57 superparamagnetic (SP) tip. The present magnetic energy flow imaging phenomenon is able to detect the flow direction of AC magnetic field energy from the recording head. A simple model for the flow direction of the AC magnetic energy is given and revealed that when the AC magnetic field energy from the surface of main pole increases, the energy from the side cross section decreases due to the periodical change of magnetization direction at the main pole area. The A-MFM magnetic energy imaging performance by 100 nm Co0.43(GdOx)0.57 SP tip is compared with the magnetic field imaging with the 25 nm Co0.80Zr0.05Nb0.15 soft magnetic (SM) tip. The spatial resolution measured by Fourier analysis for Co0.43(GdOx)0.57 SP tip is enhanced dramatically to ∼10 nm with low thermal noise, as compared to ∼13 nm by Co0.80Zr0.05Nb0.15 SM tip as well as the previously reported MFM tip. Moreover, the sensitivity and resolution are investigated for a range of head current to confirm the suitability of the magnetic energy flow imaging by Co0.43(GdOx)0.57 SP tip to low as well as high magnetic field source. Further, the A-MFM measurements are performed with the 100 nm Au coated conducting tip to investigate the possibility of electrostatic contribution in magnetic energy imaging by Co0.43(GdOx)0.57 SP tip and revealed that the present A-MFM measurement is free from any electrostatic artifacts. The present magnetic energy flow imaging phenomena with the high magnetic moment Co0.43(GdOx)0.57 SP tip provides an avenue for the analysis of the magnetic field energy component from the head field profile.

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Magnetic Recording Heads

Cited by 3 publications

References 156 publications

Injection Locking at Fractional Frequencies of Magnetic-Tunnel-Junction-Based Read Sensors’ Ferromagnetic Resonance Modes

Injection Locking at Fractional Frequencies of Magnetic-Tunnel-Junction-Based Read Sensors’ Ferromagnetic Resonance Modes

Fabrication and characterization of dendrimer-encapsulated monometallic Co nanoparticles

Magnetic energy flow imaging of magnetic recording head with enhanced resolution and sensitivity by A-MFM using high magnetic moment superparamagnetic tip

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