Abstract
Kondo insulator materials1—such as CeRhAs, CeRhSb, YbB12, Ce3Bi4Pt3 and SmB6—are 3d, 4f and 5f intermetallic compounds that have attracted considerable interest in recent years2,3,4,5. At high temperatures, they behave like metals. But as temperature is reduced, an energy gap opens in the conduction band at the Fermi energy and the materials become insulating. This contrasts with other f-electron compounds, which are metallic at all temperatures. The formation of the gap in Kondo insulators has been proposed to be a consequence of hybridization between the conduction band and the f-electron levels6,7, giving a ‘spin’ gap. If this is indeed the case, metallic behaviour should be recovered when the gap is closed by changing external parameters, such as magnetic field or pressure. Some experimental evidence suggests that the gap can be closed in SmB6 (refs 5, 8) and YbB12 (ref. 9). Here we present specific-heat measurements of Ce3Bi4Pt3 in d.c. and pulsed magnetic fields up to 60 tesla. Numerical results and the analysis of our data using the Coqblin–Schrieffer model demonstrate unambiguously a field-induced insulator-to-metal transition.
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References
Aeppli, G. & Fisk, Z. Kondo insulators. Comments Cond. Mat. Phys. 16, 155–165 (1992).
Kumigashira, H. et al. Spectral evidence for pseudogap formation in Kondo insulators CeRhAs and CeRhSb. Phys. Rev. Lett. 82, 1943–1946 (1999).
Susaki, T. et al. Temperature-dependent high-resolution photoemission study of the Kondo insulator YbB12. Phys. Rev. Lett. 82, 992–995 (1999).
Breuer, K. et al. Photoemission-study of the Kondo insulator Ce3Bi4Pt3. Europhys. Lett. 41, 565–570 (1998).
Cooley, J. C. et al. High field gap closure in the Kondo insulator SmB6. J. Supercond. 12, 171–173 (1999).
Hundley, M. F. et al. Hybridization gap in Ce3Bi4Pt3. Phys. Rev. B 42, 6842–6845 (1990).
Thompson, J. D. in Transport and Thermal Properties of f-Electron Systems (eds Fujii, H., Fujita, T. & Oomi, G.) 35–48 (Plenum, New York, 1993).
Moshchalkov, V. V. et al. SmB6 at high-pressures: the transition from insulating to the metallic Kondo lattice. J. Magn. Magn. Mat. 47&48, 289–291 (1985).
Sugiyama, K. et al. Field-induced metallic state in YbB12 under high magnetic-field. J. Phys. Soc. Jpn 57, 3946–3953 (1988).
Izawa, K. et al. Metallic ground state of CeNiSn. Phys. Rev. B 59, 2599–2603 (1999).
Hundley, M. F. et al. Magnetoresistance of the Kondo insulator Ce3Bi4Pt3. Physica B 186–188, 425–427 (1993).
Boebinger, G. S., Passner, A., Canfield, P. C. & Fisk, Z. Studies of the Kondo insulator Ce3Bi4Pt3 in 61-T pulsed magnetic-fields. Physica B 211, 227–229 (1995).
Modler, R. in Physical Phenomena at High Magnetic Fields-III (eds Fisk, Z., Gor’kov, L. & Schrieffer, R.) 154–159 (World Scientific, Singapore, 1999).
Hundley, M. F. et al. Evidence for a coherence gap in Ce3Bi4Pt3. Physica B 171, 254–257 (1991).
Jaime, M. et al. in Physical Phenomena at High Magnetic Fields-III (eds Fisk, Z., Gor’kov, L. & Schrieffer, R.) 148–153 (World Scientific, Singapore, 1999).
Severing, A. et al. Gap in the magnetic excitation spectrum of Ce3Bi4Pt3. Phys. Rev. B 44, 6832–6837 (1991).
Hewson, A. C. The Kondo Problem to Heavy Fermions (Cambridge Univ. Press, Cambridge, 1993).
Rajan, V. T. Magnetic-susceptibility and specific-heat of the Coqblin-Schrieffer model. Phys. Rev. Lett. 51, 308–311 (1983).
Schotte, K. D. & Schotte, U. Interpretation of Kondo experiments in a magnetic-field. Phys. Lett. A 55, 38–40 (1975).
Bachmann, R. et al. Heat capacity measurements on small samples at low temperatures. Rev. Sci. Instrum. 43, 205–214 (1972).
Schlottmann, P. Impurity bands in Kondo insulators. Phys. Rev. B 46, 998–1004 (1992).
Iga, F., Kasaya, M. & Kasuya, T. Specific-heat measurements of YbB12 and YbxLu1-xB12. J. Magn. Magn. Mat. 76&77, 156–158 (1988).
Mandrus, D. et al.Low-temperature thermal-expansion of SmB6: evidence for a single-energy scale in the thermodynamics of Kondo insulators. Phys. Rev. B 49, 16809–16812 (1994).
Reyes, A. P. et al. Bi-209 NMR and NQR investigation of the small-gap semiconductor Ce3Bi4Pt3. Phys. Rev. B 49, 16321–16330 (1994).
Degiorgi, L. The electrodynamic response of heavy-electron compounds. Rev. Mod. Phys. 71, 687–734 (1999).
Acknowledgements
We thank Z. Fisk, J. D. Thompson and P. Schlottmann for discussions; J. Kim for his assistance with the thermometry calibration in the 30 T d.c. magnet at the NHMFL/Tallahassee; and D. Rickel, C. Mielke, J. Betts, J. Schillig, J. Sims and M. Pacheco for technical assistance and operation of the 60TLP magnet.
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Jaime, M., Movshovich, R., Stewart, G. et al. Closing the spin gap in the Kondo insulator Ce3Bi4Pt3 at high magnetic fields. Nature 405, 160–163 (2000). https://doi.org/10.1038/35012027
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DOI: https://doi.org/10.1038/35012027
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