Head challenges for perpendicular recording at high areal density

Tsang, C.; Bonhote, C.; Dai, Qing; Do, Hoa; Knigge, Bernhard; Ikeda, Yoshihiro; Le, Quang Tuan; Lengsfield, Byron H.; Lillé, J.; Li, J.; Macdonald, Scott; Möser, Andreas; Nayak, V.; Payne, R.; Robertson, Neil; Schabes, M.E.; Smith, Neil; Takano, K.; Heijden, Paul van der; Weresin, W.; Williams, M. L.; Xiao, Min

doi:10.1109/tmag.2005.861775

Cited by 40 publications

(19 citation statements)

References 5 publications

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“…With further progress in resolution and sample preparation, force-detected MRI techniques could have significant impact on the imaging of nanoscale biological structures, even down to the scale of individual molecules. Achieving resolution Ͻ1 nm seems realistic because the current apparatus operates almost a factor of 10 away from the best demonstrated force sensitivities (37) and field gradients (38).…”

Section: Discussionmentioning

confidence: 99%

Nanoscale magnetic resonance imaging

Degen

Poggio²,

Mamin³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

488

588

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We have combined ultrasensitive magnetic resonance force microscopy (MRFM) with 3D image reconstruction to achieve magnetic resonance imaging (MRI) with resolution <10 nm. The image reconstruction converts measured magnetic force data into a 3D map of nuclear spin density, taking advantage of the unique characteristics of the "resonant slice" that is projected outward from a nanoscale magnetic tip. The basic principles are demonstrated by imaging the 1 H spin density within individual tobacco mosaic virus particles sitting on a nanometer-thick layer of adsorbed hydrocarbons. This result, which represents a 100 millionfold improvement in volume resolution over conventional MRI, demonstrates the potential of MRFM as a tool for 3D, elementally selective imaging on the nanometer scale.MRFM ͉ MRI ͉ nuclear magnetic resonance ͉ molecular structure imaging M agnetic resonance imaging (MRI) is well-known in medicine and in the neurosciences as a powerful tool for acquiring 3D morphological and functional information with resolution in the millimeter-to-submillimeter range (1, 2). Unfortunately, despite considerable effort, attempts to push the spatial resolution of conventional MRI into the realm of highresolution microscopy have been stymied by fundamental limitations, especially detection sensitivity (3, 4). Consequently, the highest resolution MRI microscopes today remain limited to voxel volumes Ͼ40 m 3 (5-8). The central issue is that MRI is based on the manipulation and detection of nuclear magnetism, and nuclear magnetism is a relatively weak physical effect. It appears that conventional coil-based inductive detection techniques simply cannot provide adequate signal-to-noise ratio for detecting voxel volumes below the micrometer size. This sensitivity constraint is unfortunate because MRI has much to offer the world of microscopy with its unique contrast modalities, its elemental selectivity, and its avoidance of radiation damage.Despite the many challenges, there is strong motivation to extend MRI to finer resolution, especially if the nanometer scale can be reached. At the nanometer scale, one might hope to directly and nondestructively image the 3D structure of individual macromolecules and molecular complexes (9). Such a powerful molecular imaging capability could be of particular interest to structural biologists trying to unravel the structure and interactions of proteins, especially for those proteins that cannot be crystallized for X-ray analysis, or are too large for conventional NMR spectroscopy. Nanoscale MRI, with its capacity for true 3D, subsurface imaging, its potential for generating contrast by selective isotopic labeling and its nondestructive nature, would be a welcome complement to the characteristics of electron microscopy. The key to pushing MRI to the nanoscale is detection sensitivity.Recently, a significant breakthrough in magnetic resonance detection sensitivity has been achieved by using magnetic resonance force microscopy (MRFM) (9-13), resulting in single spin detection for electrons ...

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Section: Discussionmentioning

confidence: 99%

Nanoscale magnetic resonance imaging

Degen

Poggio²,

Mamin³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

488

588

View full text Add to dashboard Cite

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“…This further improves write field gradient and recording performance. 4 As Kapoor and Victora 5 pointed, higher write field gradients at the transition center lead to sharper transitions ͑smaller transition jitter͒ over conventional unshielded SPT heads.…”

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confidence: 99%

A comparative study of write field distribution of trailing-edge shielded and unshielded perpendicular write heads by quantitative magnetic force microscopy

Chen

Leong

Huang

et al. 2008

Applied Physics Letters

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Three-dimensional write field distributions of trailing-edge shielded and unshielded perpendicular write heads with applied direct current write currents were studied by magnetic force microscopy (MFM) measurements. A quantitative MFM approach of two times integrating measured frequency shift at a series of tip scan heights over the perpendicular direction was proposed to measure the magnetic field strength and field gradient. Results indicate shielded heads in addition to smaller saturation write currents, exhibited more than two to three times higher write field gradients over a wide range of moderate field strength over unshielded heads, thus, producing sharper bit transition and improved signal to noise ratio as theoretically predicted.

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“…The writer was a single-pole head with a trailing shield [3], and reader was a GMR sensor with a gap length of 46 nm. A medium was a granular perpendicular double-layered media.…”

Section: Methodsmentioning

confidence: 99%