Hostname: page-component-76fb5796d-5g6vh Total loading time: 0 Render date: 2024-04-25T21:12:53.467Z Has data issue: false hasContentIssue false
  • English
  • Français

First-Principles Theory of Polarization in Ferroelectrics

Published online by Cambridge University Press:  01 January 1992

R. Resta ,
M. Posternak  and
A. Baldereschi
R. Resta
Affiliation:
SISSA, via Beirut 4, 1-34014 Trieste, Italy
A. Baldereschi
Affiliation:
IRRMA, PHB Ecublens, CH-1015 Lausanne, Switzerland
Get access

Abstract

We outline a modern theory of the spontaneous polarization P in pyroelectric and ferroelectric materials. Although P itself isnot an observable, the difference ΔP between two crystal states can indeed be measured and calculated. We define P as the difference between the polar structure and a suitably chosen nonpolar prototype structure. We previously proposed and implemented a supercell scheme in order to evaluate P in pyroelectric BeO; here we adopt an approach recently developed by King-Smith and Vanderbilt, where ΔP is obtained from the computation of Berry's phases, with no use of supercells. We apply this novel approach, which is numerically very convenient, in order to revisit our previous work on BeO. We then perform a first-principles investigation of the spontaneous polarization P of KNbO3 in its tetragonal phase, which is a well studied perovskite ferroelectric. Our calculated P value confirms the most recent experimental data. The polarization is linear in the ferroelectric distortion; the Born effective charges show strong variations from nominal ionic values, and a large inequivalence of the 0 ions. Only the highest nine valence-band states (O 2p) contribute to P, while all the other states behave as rigid core states.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 291: Symposium O – Materials Theory and Modeling , 1992 , 647
Copyright
Copyright © Materials Research Society 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Lines, M.E. and Glass, A.M., Principles and Applications of Ferroelectrics and Related Materials (Clarendon Press, Oxford, 1977).Google Scholar
2. Posternak, M., Baldereschi, A., Catellani, A. and Resta, R., Phys. Rev. Lett. 64, 1777 (1990); Baldereschi, A., Posternak, M., and Resta, R., Phys. Rev. Lett. 69, 390 (1992).Google Scholar
3. Resta, R., Posternak, M., Baldereschi, A., and Catellani, A., Ferroelectrics 111, 15 (1990).Google Scholar
4. Jerphagnon, J. and Newkirk, H.W., Appl. Phys. Letters 18, 245 (1971).Google Scholar
5. Lundqvist, S. and March, N.H. (editors), Theory of the Inhomogeneous Electron Gas (Plenum, New York, 1983).Google Scholar
6. Resta, R., Ferroelectrics, 136, 51 (1992).Google Scholar
7. King-Smith, R. D. and Vanderbilt, D., Phys. Rev. B, 15 jan. 1993.Google Scholar
8. Zak, J., Phys. Rev. Lett. 62, 2747 (1989); see also Michel, L. and Zak, J., Europhys. Lett. 18, 239 (1992).Google Scholar
9. Jansen, H. J. F. and Freeman, A. J., Phys. Rev. B. 30, 561 (1984).Google Scholar
10. Triebwasser, S., Phys. Rev. 101, 993 (1956).Google Scholar
11. Kleemann, W., Schäfer, F. J., and Fontana, M. D., Phys. Rev. B 30, 1148 (1984), and references therein.Google Scholar
12. Fontana, M. D., Métrat, G., Servoin, J. L., and Gervais, F., J. Phys.C 17, 483 (1984).Google Scholar
13. Hewat, A. W., J. Phys. C 6, 1074 (1973).Google Scholar
14.In this work the K 3p states are treated as valence states, while the Nb 4p's are calculated with the semi-core approximation following the method of Koelling, D. D., Solid State Commun. 53, 1019 (1985).Google Scholar
15. Bom, M., Rev. Mod. Phys. 17, 245 (1945).Google Scholar
16. Resta, R., Posternak, M., and Baldereschi, A. (to be published).Google Scholar