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Low-field magnetoresistance in the pyrochlore Tl2Mn2O7

Nature volume 389, pages 942–944 (1997)Cite this article

Abstract

The discovery of colossal magnetoresistance in perovskite manganites derived from LaMnO3 has renewed interest in these and related materials for possible technological applications1,2,3,4,5,6,7. But the high magnetic fields and narrow temperature windows where the large magnetoresistive responses are observed present daunting limitations. A possible avenue for overcoming these limitations is to improve the low-field response by modifying the manganites to enhance the contribution to magnetoresistance from spin-polarized tunnelling of the conduction electrons; such tunnelling, which can be very sensitive to an applied magnetic field, takes place across grain boundaries (natural or artificial) or between the manganite planes of the layered derivatives of the perovskite compounds8,9,10,11,12,13. Here we show that low-field (H) grain-boundary magnetoresistance can also be realized in a non-perovskite magnetoresistive oxide, the pyrochlore Tl2Mn2O7. Moreover, this low-field response, which persists for all temperatures below the transition to the ferromagnetic state, does not show the strong temperature-dependent decay characteristic of the perovskite-based systems. We suggest that this improved response is in part due to weaker electron-spin coupling and the lack of strong electron–lattice interactions in the pyrochlore.

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Figure 1: The temperature-dependent resistivity ρ(T) of Tl2Mn2O7 in 0 and 5 T applied fields.
Figure 2: The top panel displays the field-dependent resistivity normalized to the zero field value ρ(H)/ρo, fo.
Figure 3: Figure 3 The top panel displays the temperature dependence (normalized to TC) of the magnitude of the low-field MR ext.
Figure 4: Schematic energy-level diagram associated with transport across a grain boundary.

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References

  1. Jonker, G. H. & Van Santen, J. H. Ferromagnetic compounds of manganese with perovskite structure. Physica 16, 337–349 (1950).

    Article  CAS  ADS  Google Scholar 

  2. Searle, C. W. & Wang, S. T. Studies of the ionic ferromagnet (LaPb)MnO3. V. Electric transport and ferromagnetic properties. Can. J. Phys. 48, 2023–2031 (1970).

    Article  CAS  ADS  Google Scholar 

  3. von Helmholt, R., Wecker, J., Holzapfel, B., Schultz, L. & Samwer, K. Giant negative magnetoresistance in perovskitelike La2/3Ba1/3MnOxferromagnetic films. Phys. Rev. Lett. 71, 2331–2333 (1993).

    Article  ADS  Google Scholar 

  4. Chahara, K., Ohno, T., Kasai, M. & Kozono, Y. Magnetoresistance in magnetic manganese oxide with intrinsic antiferromagnetic spin structure. Appl. Phys. Lett. 63, 1990–1992 (1993).

    Article  CAS  ADS  Google Scholar 

  5. Jin, S. et al. Thousandfold change in resistivity in magnetoresistive La–Ca–Mn–O films. Science 264, 413–415 (1994).

    Article  CAS  ADS  Google Scholar 

  6. Shimakawa, Y., Kubo, Y. & Manako, T. Giant magnetoresistance in Tl2Mn2O7with the pyrochlore structure. Nature 379, 53–55 (1996).

    Article  CAS  ADS  Google Scholar 

  7. Cheong, S.-W., Hwang, H. Y., Batlogg, B. & Rupp, L. W. J Giant magnetoresistance in pyrochlore Tl2−xInxMn2O7. Solid State Commun. 98, 163–166 (1996).

    Article  CAS  ADS  Google Scholar 

  8. Gubkin, M. K., Perekalina, T. M., Bykov, A. V. & Chubarenko, V. A. Investigation of the electrical conductivity of some manganites with the perovskite structure. Phys. Solid State 35, 728–730 (1993).

    ADS  Google Scholar 

  9. Hwang, H. Y., Cheong, S.-W., Ong, N. P. & Batlogg, B. Spin-polarized intergrain tunneling in La2/3Sr1/3MnO3. Phys. Rev. Lett. 77, 2041–2044 (1996).

    Article  CAS  ADS  Google Scholar 

  10. Sun, J. Z. et al. Observation of large low-field magnetoresistance in trilayer perpendicular transport devices made using doped manganate perovskites. Appl. Phys. Lett. 69, 3266–3268 (1996).

    Article  CAS  ADS  Google Scholar 

  11. Kimura, T. et al. Interplane tunneling magnetoresistance in a layered manganite crystal. Science 274, 1698–1701 (1996).

    Article  CAS  ADS  Google Scholar 

  12. Gupta, A. et al. Grain-boundary effects on the magnetoresistance properties of perovskite manganite films. Phys. Rev. B 54, 15629–15632 (1996).

    Article  ADS  Google Scholar 

  13. Mathur, N. D. et al. Large low-field magnetoresistance in La0.7Ca0.3MnO3induced by artificial grain boundaries. Nature 387, 266–268 (1997).

    Article  CAS  ADS  Google Scholar 

  14. Zener, C. Interaction between the d-shells in the transition metals. II. Ferromagnetic compounds of manganese with perovskite structure. Phys. Rev. 82, 403–405 (1951).

    Article  CAS  ADS  Google Scholar 

  15. Anderson, P. W. & Hasegawa, H. Considerations on double exchange. Phys. Rev. 100, 675–681 (1955).

    Article  CAS  ADS  Google Scholar 

  16. Subramanian, M. A. et al. Colossal magnetoresistance without Mn3+/Mn4+ double exchange in the stoichiometric pyrochlore Tl2Mn2O7. Science 273, 81–84 (1996).

    Article  CAS  ADS  Google Scholar 

  17. Singh, D. J. Magnetoelectronic effects in pyrochlore Tl2Mn2O7: role of Tl–O covalency. Phys. Rev. B 55, 313–316 (1997).

    Article  CAS  ADS  Google Scholar 

  18. Millis, A. J., Littlewood, P. B. & Shraiman, B. I. Double exchange alone does not explain the resistivity of La1−xSrxMnO3. Phys. Rev. Lett. 74, 5144–5147 (1995).

    Article  CAS  ADS  Google Scholar 

  19. Dai, P. et al. Experimental evidence for the dynamic Jahn–Teller effect in La0.65Ca0.35MnO3. Phys. Rev. B 54, 3694–3697 (1996).

    Article  ADS  Google Scholar 

  20. Radaelli, P. G., Marezio, M., Hwang, H. Y., Cheong, S.-W. & Batlogg, B. Charge localization by static and dynamic distortions of the MnO6octahedra in perovskite manganites. Phys. Rev. B 54, 8992–8995 (1996).

    Article  CAS  ADS  Google Scholar 

  21. de Gennes, P.-G. Effects of double exchange in magnetic crystals. Phys. Rev. 118, 141–154 (1960).

    Article  CAS  ADS  Google Scholar 

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Acknowledgements

We thank B. Batlogg, Y. B. Kim, P. B. Littlewood, P. Majumdar, A. P. Ramirez and B. I. Shraiman for helpful discussions.

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  1. Bell Laboratories, Lucent Technologies, Murray Hill, 07974, New Jersey, USA

    H. Y. Hwang & S.-W. Cheong

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  1. H. Y. Hwang
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Hwang, H., Cheong, SW. Low-field magnetoresistance in the pyrochlore Tl2Mn2O7. Nature 389, 942–944 (1997). https://doi.org/10.1038/40093

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