Measurement of the charge and current of magnetic monopoles in spin ice (original) (raw)
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- Published: 15 October 2009
Nature volume 461, pages 956–959 (2009)Cite this article
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Abstract
The transport of electrically charged quasiparticles (based on electrons or ions) plays a pivotal role in modern technology as well as in determining the essential functions of biological organisms. In contrast, the transport of magnetic charges has barely been explored experimentally, mainly because magnetic charges, in contrast to electric ones, are generally considered at best to be convenient macroscopic parameters1,2, rather than well-defined quasiparticles. However, it was recently proposed that magnetic charges can exist in certain materials in the form of emergent excitations that manifest like point charges, or magnetic monopoles3. Here we address the question of whether such magnetic charges and their associated currents—‘magnetricity’—can be measured directly in experiment, without recourse to any material-specific theory. By mapping the problem onto Onsager's theory of electrolytes4, we show that this is indeed possible, and devise an appropriate method for the measurement of magnetic charges and their dynamics. Using muon spin rotation as a suitable local probe, we apply the method to a real material, the ‘spin ice’ Dy2Ti2O7 (refs 5–8). Our experimental measurements prove that magnetic charges exist in this material, interact via a Coulomb potential, and have measurable currents. We further characterize deviations from Ohm's law, and determine the elementary unit of magnetic charge to be 5 _μ_B Å-1, which is equal to that recently predicted using the microscopic theory of spin ice3. Our measurement of magnetic charge and magnetic current establishes an instance of a perfect symmetry between electricity and magnetism.
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References
- Morrish, A. H. The Physical Principles of Magnetism (Wiley and Sons, 1965)
Google Scholar - Jackson, J. D. Classical Electrodynamics (Wiley and Sons, 1998)
MATH Google Scholar - Castelnovo, C., Moessner, R. & Sondhi, S. L. Magnetic monopoles in spin ice. Nature 451, 42–45 (2007)
Article ADS Google Scholar - Onsager, L. Deviations from Ohm's law in weak electrolytes. J. Chem. Phys. 2, 599–615 (1934)
Article ADS CAS Google Scholar - Harris, M. J., Bramwell, S. T., McMorrow, D. F., Zeiske, T. & Godfrey, K. W. Geometrical frustration in the ferromagnetic pyrochlore Ho2Ti2O7 . Phys. Rev. Lett. 79, 2554–2557 (1997)
Article ADS CAS Google Scholar - Ramirez, A. P., Hayashi, A., Cava, R. J., Siddharthan, R. B. & Shastry, S. Zero-point entropy in spin ice. Nature 399, 333–336 (1999)
Article ADS CAS Google Scholar - Bramwell, S. T. & Gingras, M. J. P. Spin ice state in frustrated magnetic pyrochlore materials. Science 294, 1495–1501 (2001)
Article ADS CAS Google Scholar - Snyder, J. et al. Low-temperature spin freezing in the Dy2Ti2O7 spin ice. Phys. Rev. B 69, 064414 (2004)
Article ADS Google Scholar - Lee, S.-H. et al. Emergent excitations in a geometrically frustrated magnet. Nature 418, 856–858 (2002)
Article ADS CAS Google Scholar - Keren, A. et al. Dynamic properties of a diluted pyrochlore cooperative paramagnet (Tb p Y1-p )2Ti2O7 . Phys. Rev. Lett. 92, 107204 (2004)
Article ADS CAS Google Scholar - Moessner, R. & Chalker, J. T. Properties of a classical spin liquid: the Heisenberg pyrochlore antiferromagnet. Phys. Rev. Lett. 80, 2929–2932 (1998)
Article ADS CAS Google Scholar - Hermele, M., Fisher, M. P. A. & Balents, L. Pyrochlore photons: the U(1) spin liquid in a S = 1/2 three-dimensional frustrated magnet. Phys. Rev. B 69, 064404 (2004)
Article ADS Google Scholar - Burnell, F. J., Chakravarty, S. & Sondhi, S. L. Monopole flux state on the pyrochlore lattice. Phys. Rev. B 79, 144432 (2009)
Article ADS Google Scholar - Jaubert, L. D. C. & Holdsworth, P. C. W. Signature of magnetic monopole and Dirac string dynamics in spin ice. Nature Phys. 5, 258–261 (2009)
Article ADS CAS Google Scholar - Fennell, T. et al. Magnetic coulomb phase in the spin ice Ho2Ti2O7 . Science 10.1126/science.1177582 (26 August 2009)
- Morris, D. J. P. et al. Dirac strings and magnetic monopoles in spin ice Dy2Ti2O7 . Science 10.1126/science.1178868 (26 August 2009)
- Kadowaki, H. et al. Observation of magnetic monopoles in spin ice. Preprint at 〈http://arXiv.org/abs/0908.3568v2〉 (2009)
- Moore, W. J. Physical Chemistry (Longman, 1978)
Google Scholar - Bass, L. Wien dissociation as a rate process. Trans. Faraday Soc. 64, 2153–2159 (1968)
Article CAS Google Scholar - Mason, D. P. & McIlroy, D. K. A perturbation solution to the problem of Wien dissociation in weak electrolytes. Proc. R. Soc. Lond. A 359, 303–317 (1978)
Article ADS CAS Google Scholar - Uemura, Y. J. in Muon Science: Muons in Physics, Chemistry and Materials (eds Lee, S., Kilcoyne, S. & Cywinski, R.) 85–113 (SUSSP and Institute of Physics, 1998)
Google Scholar - Orendácˇ, M., Hanko, Cˇ. E. & Orendácˇová, A. Magnetocaloric study of spin relaxation in dipolar spin ice Dy2Ti2O7 . Phys. Rev. B 75, 104425 (2007)
Article ADS Google Scholar - den Hertog, B. C. & Gingras, M. J. P. Dipolar interactions and origin of spin ice in Ising pyrochlore magnets. Phys. Rev. Lett. 84, 3430–3433 (2000)
Article ADS CAS Google Scholar - Bramwell, S. T. & Harris, M. J. Frustration in Ising-type spin models on the pyrochlore lattice. J. Phys. Condens. Matter 10, L215–L220 (1998)
Article ADS CAS Google Scholar - Ryzhkin, I. A. Magnetic relaxation in rare-earth oxide pyrochlores. J. Exp. Theor. Phys. 101, 481–486 (2005)
Article ADS CAS Google Scholar - Eigen, M. & de Maeyer, L. Self-dissociation and protonic charge transport in water and ice. Proc. R. Soc. Lond. A 247, 505–533 (1958)
Article ADS CAS Google Scholar - Lago, J., Blundell, S. J. & Baines, C. _µ_SR investigation of spin dynamics in the spin-ice material Dy2Ti2O7 . J. Phys. Condens. Matter 19, 326210 (2007)
Article Google Scholar - Bertin, E. et al. Effective hyperfine temperature in frustrated Gd2Sn2O7: two level model and 155Gd Mössbauer measurements. Eur. Phys. J. B 27, 347–354 (2002)
Article ADS CAS Google Scholar - Preskill, J. Magnetic monopoles. Annu. Rev. Nucl. Part. Sci. 34, 461–530 (1984)
Article ADS CAS Google Scholar - Wang, R. F. et al. Artificial ‘spin ice’ in a geometrically frustrated lattice of nanoscale ferromagnetic islands. Nature 439, 303–306 (2006)
Article ADS CAS Google Scholar
Acknowledgements
We thank C. Castelnovo, M. J. P. Gingras, P. C. W. Holdsworth, L. Jaubert, D. F. McMorrow, R. Moessner and I. Terry for discussions.
Author Contributions S.T.B., S.R.G. and T.F. conceived the method; S.T.B. derived the theory; all authors planned the experiment; D.P. prepared the samples; S.R.G., S.T.B., R.A. and S.C. performed the experiment and analysed the data; S.T.B. and S.R.G. wrote the paper; and all authors contributed to the manuscript.
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Author notes
- S. T. Bramwell and S. R. Giblin: These authors contributed equally to this work.
Authors and Affiliations
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17–19 Gordon Street, London WC1H 0AH, UK,
S. T. Bramwell, S. Calder & R. Aldus - ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, UK ,
S. R. Giblin - Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK,
D. Prabhakaran - Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France ,
T. Fennell
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- S. T. Bramwell
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Corresponding author
Correspondence toS. T. Bramwell.
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Bramwell, S., Giblin, S., Calder, S. et al. Measurement of the charge and current of magnetic monopoles in spin ice.Nature 461, 956–959 (2009). https://doi.org/10.1038/nature08500
- Received: 18 June 2009
- Accepted: 14 September 2009
- Issue Date: 15 October 2009
- DOI: https://doi.org/10.1038/nature08500
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Editorial Summary
'Magnetricity' demonstrated in spin ice
Electric charges and currents are ubiquitous, but their magnetic counterparts are elusive. With the recent prediction, then demonstration, of the existence of magnetic 'monopoles' — particles with a net magnetic charge resembling a magnet with only one pole — in magnetically frustrated materials called 'spin ice', a system in which 'magnetricity' might be found has become available. Using the spin ice dysprosium titanate pyrochlore (Dy2Ti2O7), Bramwell et al. show that magnetic charges and their dynamics can be understood in terms of a magnetic analogue of the theory of electrolytes (substances that become ions in solution and are capable of conducting electricity). They observe real magnetic currents and determine the elementary unit of magnetic charge. The findings establish an instance of a perfect symmetry between electricity and magnetism.