Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Doping a semiconductor to create an unconventional metal

Abstract

Landau–Fermi liquid theory, with its pivotal assertion that electrons in metals can be simply understood as independent particles with effective masses replacing the free electron mass, has been astonishingly successful. This is true despite the Coulomb interactions an electron experiences from the host crystal lattice, lattice defects and the other 1022 cm-3 electrons. An important extension to the theory accounts for the behaviour of doped semiconductors1,2. Because little in the vast literature on materials contradicts Fermi liquid theory and its extensions, exceptions have attracted great attention, and they include the high-temperature superconductors3, silicon-based field-effect transistors that host two-dimensional metals4, and certain rare-earth compounds at the threshold of magnetism5,6,7,8. The origin of the non-Fermi liquid behaviour in all of these systems remains controversial. Here we report that an entirely different and exceedingly simple class of materials—doped small-bandgap semiconductors near a metal–insulator transition—can also display a non-Fermi liquid state. Remarkably, a modest magnetic field functions as a switch which restores the ordinary disordered Fermi liquid. Our data suggest that we have found a physical realization of the only mathematically rigorous route to a non-Fermi liquid, namely the ‘undercompensated Kondo effect’, where there are too few mobile electrons to compensate for the spins of unpaired electrons localized on impurity atoms9,10,11,12.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Magnetic susceptibility and phase diagram.
Figure 2: Magnetotransport.
Figure 3: Specific heat.
Figure 4: Underscreened Kondo effect.

References

  1. 1

    Al’tshuler, B. L., Aronov, A. G., Gershenson, M. E. & Sharvin, Yu. V. Quantum effects in disordered metal films. Sov. Sci. Rev. Phys. 9, 223–354 (1987)

    Google Scholar 

  2. 2

    Lee, P. A. & Ramakrishnan, T. V. Disordered electron systems. Rev. Mod. Phys. 57, 287–337 (1985)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Cava, R. J. et al. Bulk superconductivity at 91 K in a single-phase oxygen-deficient perovskite Ba2YCu3O9–δ . Phys. Rev. Lett. 58, 1676–1679 (1987)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Kravchenko, S. V. et al. Electric field scaling at a B = 0 metal–insulator transition in two dimensions. Phys. Rev. Lett. 77, 4938–4941 (1996)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Custers, J. et al. The break-up of heavy electrons at a quantum critical point. Nature 424, 524–527 (2003)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Mathur, N. D. et al. Magnetically mediated superconductivity in heavy fermion compounds. Nature 394, 39–43 (1998)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Si, Q. M., Rabello, S., Ingersent, K. & Smith, J. L. Locally critical quantum phase transitions in strongly correlated metals. Nature 413, 804–808 (2001)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Schroder, A. et al. Onset of antiferromagnetism in heavy-fermion metals. Nature 407, 351–355 (2000)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Coleman, P. & Pepin, C. Singular Fermi liquid behavior in the underscreened Kondo model. Phys. Rev. B 68, 220405 (2003)

    ADS  Article  Google Scholar 

  10. 10

    Mehta, P. et al. Regular and singular Fermi-liquid fixed points in quantum impurity models. Phys. Rev. B 72, 104430 (2005)

    ADS  Article  Google Scholar 

  11. 11

    Posazhennikova, A. & Coleman, P. Anomalous conductance of a spin-1 quantum dot. Phys. Rev. Lett. 94, 036802 (2005)

    ADS  CAS  Article  Google Scholar 

  12. 12

    Sacramento, P. D. & Schlottmann, P. Thermodynamics of the n-channel Kondo model for general n and impurity spin S in a magnetic field. J. Phys. Condens. Matter 3, 9687–9696 (1991)

    ADS  Article  Google Scholar 

  13. 13

    Wernick, J. H., Wertheim, G. K. & Sherwood, R. C. Magnetic behavior of monosilicides of 3D-transition elements. Mater. Res. Bull 7, 1431–1441 (1972)

    CAS  Article  Google Scholar 

  14. 14

    Schlesinger, Z. et al. Unconventional charge gap formation in FeSi. Phys. Rev. Lett. 71, 1748–1751 (1993)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Mattheiss, L. F. & Hamann, D. R. Band-structure and semiconducting properties of FeSi. Phys. Rev. B 47, 13114–13119 (1993)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Beille, J., Voiron, J. & Roth, M. Long period helimagnetism in the cubic-B20 Fe1–x Co x Si and Co1–x Mn x Si alloys. Solid State Commun. 47, 399–402 (1983)

    ADS  CAS  Article  Google Scholar 

  17. 17

    DiTusa, J. F. et al. Metal–insulator transitions in the Kondo insulator FeSi and classic semiconductors are similar. Phys. Rev. Lett. 78, 2831–2834 (1997)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Chernikov, M. A. et al. Low-temperature transport, optical, magnetic, and thermodynamic properties of Fe1–x Co x Si. Phys. Rev. B 56, 1366–1375 (1997)

    ADS  CAS  Article  Google Scholar 

  19. 19

    DiTusa, J. F. et al. Heavy fermion metal–Kondo insulator transition in FeSi1–x Al x . Phys. Rev. B 58, 10288–10301 (1998)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Manyala, N. et al. Magnetoresistance from quantum interference effects in ferromagnets. Nature 404, 581–584 (2000)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Manyala, N. et al. Large anomalous Hall effect in a silicon-based magnetic semiconductor. Nature Mater. 3, 255–262 (2004)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Ashcroft, N. W. & Mermin, N. D. Solid State Physics (Saunders College, Philadelphia, 1976)

    MATH  Google Scholar 

  23. 23

    Pfleiderer, C., Julian, S. R. & Lonzarich, G. G. Non-Fermi-liquid nature of the normal state of itinerant-electron ferromagnets. Nature 414, 427–430 (2001)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Rosenbaum, T. F. et al. Metal–insulator transition in a doped semiconductor. Phys. Rev. B 27, 7509–7523 (1983)

    ADS  CAS  Article  Google Scholar 

  25. 25

    Husmann, A. et al. Dynamical signature of the Mott–Hubbard transition in Ni(S,Se)2 . Science 274, 1874–1876 (1996)

    ADS  CAS  Article  Google Scholar 

  26. 26

    von Molnar, S., Briggs, A., Flouquet, J. & Remenyi, G. Electron localization in a magnetic semiconductor: Gd3–x v x S4 . Phys. Rev. Lett. 51, 706–709 (1983)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Paalanen, M. A., Graebner, J. E., Bhatt, R. N. & Sachdev, S. Thermodynamic behavior near a metal–insulator transition. Phys. Rev. Lett. 61, 597–600 (1988)

    ADS  CAS  Article  Google Scholar 

  28. 28

    Lakner, M., von Lohneysen, H., Langenfeld, A. & Wolf, P. Localized magnetic-moments in Si:P near the metal–insulator transition. Phys. Rev. B 50, 17064–17073 (1994)

    ADS  CAS  Article  Google Scholar 

  29. 29

    Bhatt, R. N. & Lee, P. A. Scaling studies of highly disordered spin-1/2 antiferromagnetic systems. Phys. Rev. Lett. 48, 344–347 (1982)

    ADS  CAS  Article  Google Scholar 

  30. 30

    Sarachik, M. P. et al. Scaling behavior in the magnetization of insulating Si:P. Phys. Rev. B 34, 387–390 (1986)

    ADS  CAS  Article  Google Scholar 

  31. 31

    Ghosh, S., Rosenbaum, T. F., Aeppli, G. & Coppersmith, S. N. Entangled quantum state of magnetic dipoles. Nature 425, 48–51 (2003)

    ADS  CAS  Article  Google Scholar 

  32. 32

    Aeppli, G. & Fisk, Z. Kondo insulators. Comments Cond. Mater. Phys. 16, 155–165 (1992)

    CAS  Google Scholar 

Download references

Acknowledgements

We thank Z. Fisk for discussions. J.F.D. acknowledges support from the National Science Foundation and G.A. acknowledges support from a Wolfson-Royal Society Research Merit Award and the Basic Technologies Programme of the UK Research Councils.

Author information

Affiliations

Authors

Corresponding author

Correspondence to J. F. DiTusa.

Supplementary information

Supplementary Notes

The file contains Supplementary Notes on the magnetoconductance and the magnetization of the materials presented in the main paper. It includes references and figure captions for the two Supplementary Figures S1-S2. (PDF 291 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Manyala, N., DiTusa, J., Aeppli, G. et al. Doping a semiconductor to create an unconventional metal. Nature 454, 976–980 (2008). https://doi.org/10.1038/nature07137

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing