DOI: 10.1038/nphys707. Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin copper oxide films

Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin copper oxide films

10.1038/nphys707

Crossref journal-article

Springer Science and Business Media LLC

Nature Physics (297)

Bibliography

Hetel, I., Lemberger, T. R., & Randeria, M. (2007). Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin copper oxide films. Nature Physics, 3(10), 700â702.

Authors 3

Iulian Hetel (first)
Thomas R. Lemberger (additional)
Mohit Randeria (additional)

References 25 Referenced 120

Uemura, Y. J. et al. Universal correlations between Tc and ns/m* (carrier density over effective mass) in high-Tc cuprate superconductors. Phys. Rev. Lett. 62, 2317–2320 (1989). (10.1103/PhysRevLett.62.2317) / Phys. Rev. Lett. by YJ Uemura (1989)
Liang, R., Bonn, D. A., Hardy, W. N. & Broun, D. Lower critical field and the superfluid density of highly underdoped YBa2Cu3O6+x single crystals. Phys. Rev. Lett. 94, 117001 (2005). (10.1103/PhysRevLett.94.117001) / Phys. Rev. Lett. by R Liang (2005)
Broun, D. M. et al. Superfluid density reveals a quantum critical point between d-wave superconductivity and a Mott insulator. Preprint at <http://xxx.lanl.gov/pdf/cond-mat/0509223v2> (2006).
Zuev, Y. L., Kim, M.-S. & Lemberger, T. R. Correlation between superfluid density and Tc of underdoped YBa2Cu3O6+x near the superconductor-insulator transition. Phys. Rev. Lett. 95, 137002 (2005). (10.1103/PhysRevLett.95.137002) / Phys. Rev. Lett. by YL Zuev (2005)
Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transition in two-dimensional systems. J. Phys. C 6, 1181–1203 (1973). (10.1088/0022-3719/6/7/010) / J. Phys. C by JM Kosterlitz (1973)
Nelson, D. R. & Kosterlitz, J. M. Universal jump in the superfluid density of two-dimensional superfluids. Phys. Rev. Lett. 39, 1201–1204 (1977). (10.1103/PhysRevLett.39.1201) / Phys. Rev. Lett. by DR Nelson (1977)
Emery, V. J. & Kivelson, S. A. Importance of phase fluctuations in superconductors with small superfluid density. Nature 374, 434–437 (1995). (10.1038/374434a0) / Nature by VJ Emery (1995)
Kamal, S. et al. Penetration depth measurements of 3D XY critical behaviour in YBa2Cu3O6.95 crystals. Phys. Rev. Lett. 73, 1845–1848 (1994). (10.1103/PhysRevLett.73.1845) / Phys. Rev. Lett. by S Kamal (1994)
Zuev, Y. et al. The role of thermal phase fluctuations in underdoped YBCO films. Preprint at <http://xxx.lanl.gov/pdf/cond-mat/0407113> (2004).
Kopp, A. & Chakravarty, S. Criticality in correlated quantum matter. Nature Phys. 1, 53–56 (2005). (10.1038/nphys105) / Nature Phys. by A Kopp (2005)
Franz, M. & Iyengar, P. Superfluid density of underdoped cuprate superconductors from a four-dimensional XY model. Phys. Rev. Lett. 96, 047007 (2006). (10.1103/PhysRevLett.96.047007) / Phys. Rev. Lett. by M Franz (2006)
Turneaure, S. J., Ulm, E. R. & Lemberger, T. R. Numerical modeling of a two-coil apparatus for measuring the magnetic penetration depth in superconducting films and arrays. J. Appl. Phys. 79, 4221–4227 (1996). (10.1063/1.362657) / J. Appl. Phys. by SJ Turneaure (1996)
Turneaure, S. J., Pesetski, A. A. & Lemberger, T. R. Numerical modeling and experimental consideration for a two-coil apparatus to measure the complex conductivity of superconducting films. J. Appl. Phys. 83, 4334–4343 (1998). (10.1063/1.367193) / J. Appl. Phys. by SJ Turneaure (1998)
Li, Q. et al. Interlayer coupling effect in high-Tc superconductors probed by YBa2Cu3O7−x/PrBa2Cu3O7−x superlattices. Phys. Rev. Lett. 64, 3086–3089 (1990). (10.1103/PhysRevLett.64.3086) / Phys. Rev. Lett. by Q Li (1990)
Lowndes, D. H., Norton, D. P. & Budai, J. D. Superconductivity in nonsymmetric epitaxial YBa2Cu3O7−x/PrBa2Cu3O7−x superlattices: the superconducting behaviour of Cu–O bilayers. Phys. Rev. Lett. 65, 1160–1163 (1990). (10.1103/PhysRevLett.65.1160) / Phys. Rev. Lett. by DH Lowndes (1990)
Terashima, T. et al. Superconductivity of one-unit-cell thick YBa2Cu3O7 thin film. Phys. Rev. Lett. 67, 1362–1365 (1991). (10.1103/PhysRevLett.67.1362) / Phys. Rev. Lett. by T Terashima (1991)
Bishop, D. & Reppy, J. D. Study of superfluid transition in two-dimensional 4He films. Phys. Rev. Lett. 40, 1727–1730 (1978). (10.1103/PhysRevLett.40.1727) / Phys. Rev. Lett. by D Bishop (1978)
McQueeney, D., Agnolet, G. & Reppy, J. D. Surface superfluidity in dilute 4He-3He mixtures. Phys. Rev. Lett. 52, 1325–1329 (1984). (10.1103/PhysRevLett.52.1325) / Phys. Rev. Lett. by D McQueeney (1984)
Benfatto, L., Castellani, C. & Giamarchi, T. Kosterlitz–Thouless behaviour in layered superconductors: the role of the vortex core energy. Phys. Rev. Lett. 98, 117008 (2006). (10.1103/PhysRevLett.98.117008) / Phys. Rev. Lett. by L Benfatto (2006)
Sachdev, S. Quantum Phase Transitions (Cambridge Univ. Press, Cambridge, 1999). / Quantum Phase Transitions by S Sachdev (1999)
Fisher, M. P. A., Weichman, P. B., Grinstein, G. & Fisher, D. S. Boson localization in the superfluid-insulator transition. Phys. Rev. B 40, 546–570 (1989). (10.1103/PhysRevB.40.546) / Phys. Rev. B by MPA Fisher (1989)
Homes, C. C., Dordevic, S. V., Valla, T. & Strongin, M. Scaling of the superfluid density in high-temperature superconductors. Phys. Rev. B 72, 134517 (2005). (10.1103/PhysRevB.72.134517) / Phys. Rev. B by CC Homes (2005)
Homes, C. C. et al. A universal scaling relation in high-temperature superconductors. Nature 430, 539–541 (2004). (10.1038/nature02673) / Nature by CC Homes (2004)
Kawasaky, M. et al. Atomic control of SrTiO3 crystal surface. Science 266, 1540–1542 (1994). (10.1126/science.266.5190.1540) / Science by M Kawasaky (1994)
Koster, G., Kropman, B. L., Rijnders, G. L. H. M., Blank, D. H. A. & Rogalla, H. Quasi-ideal strontium titanate crystal surfaces through formation of strontium hydroxide. Appl. Phys. Lett. 73, 2920–2922 (1998). (10.1063/1.122630) / Appl. Phys. Lett. by G Koster (1998)

Dates

Type	When
Created	18 years ago (Aug. 26, 2007, 2:29 p.m.)
Deposited	4 months, 2 weeks ago (April 11, 2025, 3:49 a.m.)
Indexed	2 weeks, 6 days ago (Aug. 6, 2025, 8:03 a.m.)
Issued	18 years ago (Aug. 26, 2007)
Published	18 years ago (Aug. 26, 2007)
Published Online	18 years ago (Aug. 26, 2007)
Published Print	17 years, 10 months ago (Oct. 1, 2007)

Funders 0

None

BibTeX

@article{Hetel_2007, title={Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin copper oxide films}, volume={3}, ISSN={1745-2481}, url={http://dx.doi.org/10.1038/nphys707}, DOI={10.1038/nphys707}, number={10}, journal={Nature Physics}, publisher={Springer Science and Business Media LLC}, author={Hetel, Iulian and Lemberger, Thomas R. and Randeria, Mohit}, year={2007}, month=aug, pages={700–702} }

JSON

{
  "indexed": {
    "date-parts": [
      [
        2025,
        8,
        6
      ]
    ],
    "date-time": "2025-08-06T12:03:08Z",
    "timestamp": 1754481788505,
    "version": "3.40.4"
  },
  "reference-count": 25,
  "publisher": "Springer Science and Business Media LLC",
  "issue": "10",
  "license": [
    {
      "start": {
        "date-parts": [
          [
            2007,
            8,
            26
          ]
        ],
        "date-time": "2007-08-26T00:00:00Z",
        "timestamp": 1188086400000
      },
      "content-version": "tdm",
      "delay-in-days": 0,
      "URL": "https://www.springernature.com/gp/researchers/text-and-data-mining"
    },
    {
      "start": {
        "date-parts": [
          [
            2007,
            8,
            26
          ]
        ],
        "date-time": "2007-08-26T00:00:00Z",
        "timestamp": 1188086400000
      },
      "content-version": "vor",
      "delay-in-days": 0,
      "URL": "https://www.springernature.com/gp/researchers/text-and-data-mining"
    }
  ],
  "content-domain": {
    "domain": [
      "link.springer.com"
    ],
    "crossmark-restriction": false
  },
  "published-print": {
    "date-parts": [
      [
        2007,
        10
      ]
    ]
  },
  "DOI": "10.1038/nphys707",
  "type": "journal-article",
  "created": {
    "date-parts": [
      [
        2007,
        8,
        26
      ]
    ],
    "date-time": "2007-08-26T18:29:46Z",
    "timestamp": 1188152986000
  },
  "page": "700-702",
  "update-policy": "https://doi.org/10.1007/springer_crossmark_policy",
  "source": "Crossref",
  "is-referenced-by-count": 120,
  "title": "Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin copper oxide films",
  "prefix": "10.1038",
  "volume": "3",
  "author": [
    {
      "given": "Iulian",
      "family": "Hetel",
      "sequence": "first",
      "affiliation": []
    },
    {
      "given": "Thomas R.",
      "family": "Lemberger",
      "sequence": "additional",
      "affiliation": []
    },
    {
      "given": "Mohit",
      "family": "Randeria",
      "sequence": "additional",
      "affiliation": []
    }
  ],
  "member": "297",
  "published-online": {
    "date-parts": [
      [
        2007,
        8,
        26
      ]
    ]
  },
  "reference": [
    {
      "key": "BFnphys707_CR1",
      "doi-asserted-by": "publisher",
      "first-page": "2317",
      "DOI": "10.1103/PhysRevLett.62.2317",
      "volume": "62",
      "author": "YJ Uemura",
      "year": "1989",
      "unstructured": "Uemura, Y. J. et al. Universal correlations between Tc and ns/m* (carrier density over effective mass) in high-Tc cuprate superconductors. Phys. Rev. Lett. 62, 2317\u20132320 (1989).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR2",
      "doi-asserted-by": "publisher",
      "first-page": "117001",
      "DOI": "10.1103/PhysRevLett.94.117001",
      "volume": "94",
      "author": "R Liang",
      "year": "2005",
      "unstructured": "Liang, R., Bonn, D. A., Hardy, W. N. & Broun, D. Lower critical field and the superfluid density of highly underdoped YBa2Cu3O6+x single crystals. Phys. Rev. Lett. 94, 117001 (2005).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR3",
      "unstructured": "Broun, D. M. et al. Superfluid density reveals a quantum critical point between d-wave superconductivity and a Mott insulator. Preprint at &lt;http://xxx.lanl.gov/pdf/cond-mat/0509223v2&gt; (2006)."
    },
    {
      "key": "BFnphys707_CR4",
      "doi-asserted-by": "publisher",
      "first-page": "137002",
      "DOI": "10.1103/PhysRevLett.95.137002",
      "volume": "95",
      "author": "YL Zuev",
      "year": "2005",
      "unstructured": "Zuev, Y. L., Kim, M.-S. & Lemberger, T. R. Correlation between superfluid density and Tc of underdoped YBa2Cu3O6+x near the superconductor-insulator transition. Phys. Rev. Lett. 95, 137002 (2005).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR5",
      "doi-asserted-by": "publisher",
      "first-page": "1181",
      "DOI": "10.1088/0022-3719/6/7/010",
      "volume": "6",
      "author": "JM Kosterlitz",
      "year": "1973",
      "unstructured": "Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transition in two-dimensional systems. J. Phys. C 6, 1181\u20131203 (1973).",
      "journal-title": "J. Phys. C"
    },
    {
      "key": "BFnphys707_CR6",
      "doi-asserted-by": "publisher",
      "first-page": "1201",
      "DOI": "10.1103/PhysRevLett.39.1201",
      "volume": "39",
      "author": "DR Nelson",
      "year": "1977",
      "unstructured": "Nelson, D. R. & Kosterlitz, J. M. Universal jump in the superfluid density of two-dimensional superfluids. Phys. Rev. Lett. 39, 1201\u20131204 (1977).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR7",
      "doi-asserted-by": "publisher",
      "first-page": "434",
      "DOI": "10.1038/374434a0",
      "volume": "374",
      "author": "VJ Emery",
      "year": "1995",
      "unstructured": "Emery, V. J. & Kivelson, S. A. Importance of phase fluctuations in superconductors with small superfluid density. Nature 374, 434\u2013437 (1995).",
      "journal-title": "Nature"
    },
    {
      "key": "BFnphys707_CR8",
      "doi-asserted-by": "publisher",
      "first-page": "1845",
      "DOI": "10.1103/PhysRevLett.73.1845",
      "volume": "73",
      "author": "S Kamal",
      "year": "1994",
      "unstructured": "Kamal, S. et al. Penetration depth measurements of 3D XY critical behaviour in YBa2Cu3O6.95 crystals. Phys. Rev. Lett. 73, 1845\u20131848 (1994).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR9",
      "unstructured": "Zuev, Y. et al. The role of thermal phase fluctuations in underdoped YBCO films. Preprint at &lt;http://xxx.lanl.gov/pdf/cond-mat/0407113&gt; (2004)."
    },
    {
      "key": "BFnphys707_CR10",
      "doi-asserted-by": "publisher",
      "first-page": "53",
      "DOI": "10.1038/nphys105",
      "volume": "1",
      "author": "A Kopp",
      "year": "2005",
      "unstructured": "Kopp, A. & Chakravarty, S. Criticality in correlated quantum matter. Nature Phys. 1, 53\u201356 (2005).",
      "journal-title": "Nature Phys."
    },
    {
      "key": "BFnphys707_CR11",
      "doi-asserted-by": "publisher",
      "first-page": "047007",
      "DOI": "10.1103/PhysRevLett.96.047007",
      "volume": "96",
      "author": "M Franz",
      "year": "2006",
      "unstructured": "Franz, M. & Iyengar, P. Superfluid density of underdoped cuprate superconductors from a four-dimensional XY model. Phys. Rev. Lett. 96, 047007 (2006).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR12",
      "doi-asserted-by": "publisher",
      "first-page": "4221",
      "DOI": "10.1063/1.362657",
      "volume": "79",
      "author": "SJ Turneaure",
      "year": "1996",
      "unstructured": "Turneaure, S. J., Ulm, E. R. & Lemberger, T. R. Numerical modeling of a two-coil apparatus for measuring the magnetic penetration depth in superconducting films and arrays. J. Appl. Phys. 79, 4221\u20134227 (1996).",
      "journal-title": "J. Appl. Phys."
    },
    {
      "key": "BFnphys707_CR13",
      "doi-asserted-by": "publisher",
      "first-page": "4334",
      "DOI": "10.1063/1.367193",
      "volume": "83",
      "author": "SJ Turneaure",
      "year": "1998",
      "unstructured": "Turneaure, S. J., Pesetski, A. A. & Lemberger, T. R. Numerical modeling and experimental consideration for a two-coil apparatus to measure the complex conductivity of superconducting films. J. Appl. Phys. 83, 4334\u20134343 (1998).",
      "journal-title": "J. Appl. Phys."
    },
    {
      "key": "BFnphys707_CR14",
      "doi-asserted-by": "publisher",
      "first-page": "3086",
      "DOI": "10.1103/PhysRevLett.64.3086",
      "volume": "64",
      "author": "Q Li",
      "year": "1990",
      "unstructured": "Li, Q. et al. Interlayer coupling effect in high-Tc superconductors probed by YBa2Cu3O7\u2212x/PrBa2Cu3O7\u2212x superlattices. Phys. Rev. Lett. 64, 3086\u20133089 (1990).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR15",
      "doi-asserted-by": "publisher",
      "first-page": "1160",
      "DOI": "10.1103/PhysRevLett.65.1160",
      "volume": "65",
      "author": "DH Lowndes",
      "year": "1990",
      "unstructured": "Lowndes, D. H., Norton, D. P. & Budai, J. D. Superconductivity in nonsymmetric epitaxial YBa2Cu3O7\u2212x/PrBa2Cu3O7\u2212x superlattices: the superconducting behaviour of Cu\u2013O bilayers. Phys. Rev. Lett. 65, 1160\u20131163 (1990).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR16",
      "doi-asserted-by": "publisher",
      "first-page": "1362",
      "DOI": "10.1103/PhysRevLett.67.1362",
      "volume": "67",
      "author": "T Terashima",
      "year": "1991",
      "unstructured": "Terashima, T. et al. Superconductivity of one-unit-cell thick YBa2Cu3O7 thin film. Phys. Rev. Lett. 67, 1362\u20131365 (1991).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR17",
      "doi-asserted-by": "publisher",
      "first-page": "1727",
      "DOI": "10.1103/PhysRevLett.40.1727",
      "volume": "40",
      "author": "D Bishop",
      "year": "1978",
      "unstructured": "Bishop, D. & Reppy, J. D. Study of superfluid transition in two-dimensional 4He films. Phys. Rev. Lett. 40, 1727\u20131730 (1978).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR18",
      "doi-asserted-by": "publisher",
      "first-page": "1325",
      "DOI": "10.1103/PhysRevLett.52.1325",
      "volume": "52",
      "author": "D McQueeney",
      "year": "1984",
      "unstructured": "McQueeney, D., Agnolet, G. & Reppy, J. D. Surface superfluidity in dilute 4He-3He mixtures. Phys. Rev. Lett. 52, 1325\u20131329 (1984).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR19",
      "doi-asserted-by": "publisher",
      "first-page": "117008",
      "DOI": "10.1103/PhysRevLett.98.117008",
      "volume": "98",
      "author": "L Benfatto",
      "year": "2006",
      "unstructured": "Benfatto, L., Castellani, C. & Giamarchi, T. Kosterlitz\u2013Thouless behaviour in layered superconductors: the role of the vortex core energy. Phys. Rev. Lett. 98, 117008 (2006).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFnphys707_CR20",
      "volume-title": "Quantum Phase Transitions",
      "author": "S Sachdev",
      "year": "1999",
      "unstructured": "Sachdev, S. Quantum Phase Transitions (Cambridge Univ. Press, Cambridge, 1999)."
    },
    {
      "key": "BFnphys707_CR21",
      "doi-asserted-by": "publisher",
      "first-page": "546",
      "DOI": "10.1103/PhysRevB.40.546",
      "volume": "40",
      "author": "MPA Fisher",
      "year": "1989",
      "unstructured": "Fisher, M. P. A., Weichman, P. B., Grinstein, G. & Fisher, D. S. Boson localization in the superfluid-insulator transition. Phys. Rev. B 40, 546\u2013570 (1989).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFnphys707_CR22",
      "doi-asserted-by": "publisher",
      "first-page": "134517",
      "DOI": "10.1103/PhysRevB.72.134517",
      "volume": "72",
      "author": "CC Homes",
      "year": "2005",
      "unstructured": "Homes, C. C., Dordevic, S. V., Valla, T. & Strongin, M. Scaling of the superfluid density in high-temperature superconductors. Phys. Rev. B 72, 134517 (2005).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFnphys707_CR23",
      "doi-asserted-by": "publisher",
      "first-page": "539",
      "DOI": "10.1038/nature02673",
      "volume": "430",
      "author": "CC Homes",
      "year": "2004",
      "unstructured": "Homes, C. C. et al. A universal scaling relation in high-temperature superconductors. Nature 430, 539\u2013541 (2004).",
      "journal-title": "Nature"
    },
    {
      "key": "BFnphys707_CR24",
      "doi-asserted-by": "publisher",
      "first-page": "1540",
      "DOI": "10.1126/science.266.5190.1540",
      "volume": "266",
      "author": "M Kawasaky",
      "year": "1994",
      "unstructured": "Kawasaky, M. et al. Atomic control of SrTiO3 crystal surface. Science 266, 1540\u20131542 (1994).",
      "journal-title": "Science"
    },
    {
      "key": "BFnphys707_CR25",
      "doi-asserted-by": "publisher",
      "first-page": "2920",
      "DOI": "10.1063/1.122630",
      "volume": "73",
      "author": "G Koster",
      "year": "1998",
      "unstructured": "Koster, G., Kropman, B. L., Rijnders, G. L. H. M., Blank, D. H. A. & Rogalla, H. Quasi-ideal strontium titanate crystal surfaces through formation of strontium hydroxide. Appl. Phys. Lett. 73, 2920\u20132922 (1998).",
      "journal-title": "Appl. Phys. Lett."
    }
  ],
  "container-title": "Nature Physics",
  "original-title": [],
  "language": "en",
  "link": [
    {
      "URL": "https://www.nature.com/articles/nphys707.pdf",
      "content-type": "application/pdf",
      "content-version": "vor",
      "intended-application": "text-mining"
    },
    {
      "URL": "https://www.nature.com/articles/nphys707",
      "content-type": "text/html",
      "content-version": "vor",
      "intended-application": "text-mining"
    },
    {
      "URL": "https://www.nature.com/articles/nphys707.pdf",
      "content-type": "application/pdf",
      "content-version": "vor",
      "intended-application": "similarity-checking"
    }
  ],
  "deposited": {
    "date-parts": [
      [
        2025,
        4,
        11
      ]
    ],
    "date-time": "2025-04-11T07:49:07Z",
    "timestamp": 1744357747000
  },
  "score": 1,
  "resource": {
    "primary": {
      "URL": "https://www.nature.com/articles/nphys707"
    }
  },
  "subtitle": [],
  "short-title": [],
  "issued": {
    "date-parts": [
      [
        2007,
        8,
        26
      ]
    ]
  },
  "references-count": 25,
  "journal-issue": {
    "issue": "10",
    "published-print": {
      "date-parts": [
        [
          2007,
          10
        ]
      ]
    }
  },
  "alternative-id": [
    "BFnphys707"
  ],
  "URL": "http://dx.doi.org/10.1038/nphys707",
  "relation": {},
  "ISSN": [
    "1745-2473",
    "1745-2481"
  ],
  "subject": [],
  "container-title-short": "Nature Phys",
  "published": {
    "date-parts": [
      [
        2007,
        8,
        26
      ]
    ]
  },
  "assertion": [
    {
      "value": "30 April 2007",
      "order": 1,
      "name": "received",
      "label": "Received",
      "group": {
        "name": "ArticleHistory",
        "label": "Article History"
      }
    },
    {
      "value": "20 July 2007",
      "order": 2,
      "name": "accepted",
      "label": "Accepted",
      "group": {
        "name": "ArticleHistory",
        "label": "Article History"
      }
    },
    {
      "value": "26 August 2007",
      "order": 3,
      "name": "first_online",
      "label": "First Online",
      "group": {
        "name": "ArticleHistory",
        "label": "Article History"
      }
    },
    {
      "value": "The authors declare no competing financial interests.",
      "order": 1,
      "name": "Ethics",
      "group": {
        "name": "EthicsHeading",
        "label": "Competing interests"
      }
    }
  ]
}