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Nuclear magnetic resonance imaging with 90-nm resolution

Nature Nanotechnology volume 2, pages 301306 (2007) | Download Citation

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Abstract

Magnetic resonance imaging (MRI) is a powerful imaging technique that typically operates on the scale of millimetres to micrometres. Conventional MRI is based on the manipulation of nuclear spins with radio-frequency fields, and the subsequent detection of spins with induction-based techniques. An alternative approach, magnetic resonance force microscopy (MRFM), uses force detection to overcome the sensitivity limitations of conventional MRI. Here, we show that the two-dimensional imaging of nuclear spins can be extended to a spatial resolution better than 100 nm using MRFM. The imaging of 19F nuclei in a patterned CaF2 test object was enabled by a detection sensitivity of roughly 1,200 nuclear spins at a temperature of 600 mK. To achieve this sensitivity, we developed high-moment magnetic tips that produced field gradients up to 1.4 × 106 T m−1, and implemented a measurement protocol based on force-gradient detection of naturally occurring spin fluctuations. The resulting detection volume was less than 650 zeptolitres. This is 60,000 times smaller than the previous smallest volume for nuclear magnetic resonance microscopy, and demonstrates the feasibility of pushing MRI into the nanoscale regime.

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Acknowledgements

We thank J. Marohn for discussions on the CERMIT technique, B. Hughes for assistance with magnetic tip preparation, B. W. Chui for cantilever fabrication, and D. Pearson and B. Melior for technical support. We acknowledge support from the DARPA QUIST program administered through the US Army Research Office, the Swiss National Science Foundation, and the Stanford-IBM Center for Probing the Nanoscale, a NSF Nanoscale Science and Engineering Center.

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Affiliations

  1. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA

    • H. J. Mamin
    • , M. Poggio
    • , C. L. Degen
    •  & D. Rugar
  2. Center for Probing the Nanoscale, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA

    • M. Poggio

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Contributions

H.J.M., D. R. and M.P. conceived, designed and performed the experiment. M.P. and D.R. implemented the RF sweep method. D.R., M.P. and H.J.M. performed tip-field modelling. C.L.D. modelled the cyclic-CERMIT protocol and performed the image simulation. H.J.M. and D.R. co-wrote the paper. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to H. J. Mamin.

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DOI

https://doi.org/10.1038/nnano.2007.105

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