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Volumn 151, Issue 6, 2011, Pages 474-477

An atomistic approach to the dielectric modes of BaTiO3 and SrTiO3

Author keywords

A. Ferroelectrics; D. Anharmonicity; D. Dielectric response

Indexed keywords

A. FERROELECTRICS; ANHARMONICITIES; ATOMISTIC APPROACH; DIELECTRIC RESPONSE; LATTICE DYNAMICS; LOW-FREQUENCY RAMAN; PHENOMENOLOGICAL MODELS; PHONON MODE; POLAR COORDINATE; SRTIO;

EID: 79951511494     PISSN: 00381098     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.ssc.2010.12.033     Document Type: Article
Times cited : (9)

References (46)
  • 32
    • 79951516509 scopus 로고    scopus 로고
    • H.-Y. Deng, C.H. Lam, H. Huang, (unpublished)
    • H.-Y. Deng, C.H. Lam, H. Huang, (unpublished).
  • 33
    • 79951514905 scopus 로고    scopus 로고
    • note
    • 22, 52.92 ), where γo and αl are the quartic and quadratic coefficients of the double-well potential, respectively. With these parameters, we found that ωl depends on T sensitively, especially at moderate temperatures. For T > 25 K, its square reasonably complies with the Barrett formula (J.H. Barrett, Phys. Rev. 86 (1952) 118). However, ωl does not saturate below 25 K. We believe this deviation reflects that, below 25 K, SPA no longer applies and a simple tunneling picture may be more suitable. This idea also explains why isotope substitution has a considerable effect only at low temperatures. We have adopted this idea in our calculations. Also, for BT, the temperature dependence of the S mode is neglected for simplicity, which however should be important for quantitative features, as suggested by the expression of ωs.
  • 39
    • 79951511824 scopus 로고    scopus 로고
    • note
    • When θ = 1, σi will be turned into static variables, namely, it shall not have its own dynamics. Nevertheless, thermal fluctuations will impose incoherent dynamics upon it [1]. Because it is in a deep double-well potential, this kind of dynamics will have pronounced physical consequences. On the contrary, no interesting physics can be forecasted in connection with the thermal fluctuations of ηi at θ = 0, since it is in a featureless single-well potential.
  • 43
    • 49949134917 scopus 로고
    • K. Kobayashi Phys. Lett. A 26 1967 55 Actually, it turns out that the dielectric function for ST at low temperatures can be written as ε (ω) = ε∞ + QT [ Dr (ω) - iωDi (ω) ] - 1 Q, where Dr differs from D ′ only at their first diagonal element, i.e., Dr (1, 1 ) = meff (Ω 2 - ω2 ), with meff = Latin small letter h with stroke 2 [ 4 tanh (Ω 0 kB T ) Ω 0 ] - 1. Similarly, except for Di (1, 1 ) = meff ΓΩ, Di is identical to D ″
    • (1967) Phys. Lett. A , vol.26 , pp. 55
    • Kobayashi, K.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.