Sains Malaysiana 34(2): 73-76 (2005)

 

Mod Fonon dan Gandingan Elektron-Fonon untuk

Kesuperkonduksian dalam Kuprat Dua Dimensi

(Phonon Mode and Electron-Phonon Coupling for Superconductivity

 in Two-Dimensional Cuprates)

 

 

Roslan Abd Shukor

Pusat Pengajian Fizik Gunaan

Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia 43650 UKM Bangi

Selangor, D.E. Malaysia

 

 

 

ABSTRAK

 

Pemalar gandingan elektron-fonon dalam superkonduktor suhu tinggi berasaskan kuprum oksida telah diukur melalui Kaedah akustik. Hubungan terus antara pemalar gandingan elektron-fonon sistem dua dimensi senario van Hove, lvH dengan suhu genting telah dicerap. Suhu cirian Debye bagaimana pun tidak berkorelasi dengan suhu genting. Keputusan ini menunjukkanfrekuensi Debye dan gandingan elektron-fonon dalam sistem dua dimensi saling mempengaruhi dan mempunyai kesan dalam menentukan suhu genting. Pemalar gandingan van Hove adalah dalam julat lvH = 0.025 – 0.060 konsisten dengan pembentukan pasangan Cooper oleh interaksi elektronfonon bagi mod pernafasan oksigen tak diagonal dalam satah Cu02.

 

Katakunci: Gandingan elektron-fonon, suhu Debye, senario van Hove, mod pernafasan

 

 

ABSTRACT

 

The electron-phonon coupling constant in the cup rate high temperature superconductors has been determined by the acoustic method. A proportional relation between the electron-phonon coupling constant for a two dimensional system in the van Hove scenario, lvH and the transition temperature is observed. The characteristic Debye temperature, however does not correlate with the transition temperature. Our results show the importance of interplay between the Debye frequency and electron-phonon coupling in the two dimensional system and their variations have combined effect in governing the transition temperature. The van Hove electron-phonon coupling constant is in the range of lvH  = 0.025 – 0.060 consistent with Cooper pairs formation by non-diagonal electron-phonon interaction of the in-plane oxygen breathing mode in the CuO2 plane.      .

 

Keyword: Electron-phonon coupling-debye temperature, van scenario, breathing mode.

 

 

RUJUKAN/REFERENCES

 

Abd-Shukor, R. 2002. Acoustic Debye Temperature and Role of Phonons in Cuprate and Related Superconductors. Superconductor Science and Technology 15(3): 435-438.

Abrikosov, A.A., Campuzano, J.c. & Gofron, K., 1993. Experimentally Observed Extended Saddle Point Singularity in the Energy Spectrum of Yttrium Barium Copper Oxides (Yba2Cu3O6.9 and Yba2Cu4O8) and Some of the Consequences. Physica C 214: 73-79.

Dessau, D. S., Shen, D. X., King, D. M., Marshall, D. S., Lombardo, L. W., Dickinson, P.H., Loeser, A.G., DiCarlo, J. & Park, C.H., 1993. Key Features in the Measured Band Structure of Bismuth Strontium Calcium Copper Oxide (Bi2Sr2CaCu2O8+d): Flat Bands at EF and Fermi Surface Nesting. Phys. Rev. Lett. 71: 2781-2784.

Devereaux T. P., Cuk, T., Shen Z. X. & Nagaosa, N., 2004. Anisotropic Electron-Phonon Interaction in the Cuprates. Phys. Rev. Lett. 93(11): 117004/1-117004/4.

Devereaux, T.P., Virosztek, A., Zawadowski, A., Opel, M, Mulier, P.F., Hoffmann, C. Philipp, R., Nemetschek, Hackl, R., Erb, A., Walker, E., Berger, H.& Farro, L.1998. Enhanced Electron-Phonon Coupling and its Irrelevance to High Tc Supercond. Solid State Comm. 108: 407-411.

Friedl, B., Thomsen, c., Schoenherr, E. & Cardona, M. 1990. Electron-Phonon Coupling of Apex Oxygen in Rba2Cu3O708. Solid State Comm. 76: 1107-1110.

Getino, G. M., Rubio, H. & de Lano, M. 1992. Cooper Pairing in the van Hove Singularity Scenario of High Temperature Superconductivity. Solid State Comm. 83(11): 891-893.

Gofron, K., Campuzano, J.C., Abrikosov, A.A., Lindroos, M., Bansil, A., Ding, H., Koelling, D. & Dabrowski, B. 1994. Observation of an "Extended" van Hove Singularity in YBa2Cu4O8 by Ultrahigh Energy Resolution Angle-Resolved Photoemission. Phys. Rev. Lett. 73: 3302-3305.

Lanzara, A., Bogdanov, P.Y., Zhou, XJ., Kellar, S.A., Feng, D.L., Lu, E.D., Yoshida, T., Eisaki, H., Fujimori, H., Kishio, K., Shimoyama, J-I., Noda, T., Uchida, S., Hussain, Z., & Shen, Z.X., 200 I. Evidence for Ubiquitous Strong Electron-Phonon Coupling in High-Temperature Superconductors. Nature 412: 510-514.

Newns, D.M., Tsuei, C.C. & Pattnaik, P.C., 1995. van Hove Scenario for d-wave Superconductivity in Cuprates. Phys. Rev. B 52(18): 13611-13618.

Novikov, DL & Freeman, AJ., 1993. van Hove Singularities and the Role of Doping in the Stabilization, Synthesis and Superconductivity of HgBa2Can-1.,CunO2n+2+_ . Physica C 216-273.    

Piekarz, P. & Konior, J., 1999. Electron-phonon Interaction in the Cuprates: Breathing Versus Buckling Mode. Phys. Rev. B 59(22): 14697-14701.

Shimada, D. & Tsuda, N. 2002. On the Isotope Effect in Tc for Cuprate Superconductors. Physica C 371: 52-56.

Skint, John A., Kim, Mun-Seog, Lemberger, Thomas R., Greibe, T. & Naito, M., 2003. Superconducting Density of States from the Magnetic Penetration Depth of Electron-Doped Cuprates La2xCexCu04. and Prz.xCexCuO4. arXiv:cond-mat/0301174.

Tang J.M. & Flatte, M.E., 2002. van Hove Features in Bi2Sr2CaCu2O- and Effective Parameters for Ni Impurities Inferred from STM Spectra, arXiv: cond-mat/02055079.

 

 

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