Structural Transitions in a La0.82Ca0.18MnO3 Single Crystal

R.I. Zainullina, N.S. Bannikova, D.A. Shulyatev show affiliations and emails
Received 21 March 2018; Accepted 07 May 2018;
This paper is written in Russian
Citation: R.I. Zainullina, N.S. Bannikova, D.A. Shulyatev. Structural Transitions in a La0.82Ca0.18MnO3 Single Crystal. Lett. Mater., 2018, 8(3) 258-262
BibTex   https://doi.org/10.22226/2410-3535-2018-3-258-262

Abstract

At cooling from T~ 400 K a La0.82Ca0.18MnO3 single crystal undergoes the transition from pseudocubic O* phase to Jahn-Teller O' phase and the reverse transition from the O' to low temperature O* phase. It is surprising that low values of the internal friction are observed for crystal phase O' with significant Jahn-Teller distortions of oxygen octahedra.The influence of structural transitions from high-temperature pseudocubic O* to the Jahn−Teller O' phase and reverse transition from O' to a low-temperature O* phase on the elastic, magnetic, and transport properties of a La0.82Ca0.18MnO3 single crystal when the temperature is decreased from 400 K is studied. Significant anomalies are observed in the temperature dependences of the velocity of longitudinal sound waves and the internal friction. The sound velocity and the internal friction in the Jahn−Teller O' phase are significantly lower than those in the pseudocubic O* phase. The structural transitions take place in the temperature range 30−50 K. Majority carriers in the low-temperature O* phase are electrons, whereas majority carriers in the O' and high-temperature O* phases are holes. Electronic states are characterized by substantially stronger spin−orbit interaction than hole states. The positive magnetoresistance is observed in low magnetic fields in the low-temperature O* phase. At a certain field, the magnetoresistance changes its sign. Such magnetoresistance has not been observed in the La−Sr and La−Ba manganites. Positive magnetoresistance indicates significant anisotropy of the transport properties of the low-temperature O* phase in the La0.82Ca0.18MnO3 single crystal. It is established that the magnetic and transport properties of the low-temperature ferromagnetic O*phase differ markedly from those of the ferromagnetic Jahn—Teller O' phase.

References (9)

1. E. Dagotto. Nanoscale Phase Separation and Colossal Magnetoresistance: The Physics of Manganites and Related Compounds. Springer, Berlin (2002) 422 p.
2. R. I. Zainullina, N. G. Bebenin, V. V. Ustinov, Ya. M. Mukovskii, D. A. Shulyatev. Phys. Rev. B. 76, 014408 (2007). Crossref
3. N. G. Bebenin. Phys. Met. Metallogr. 111(3), 236 (2011). Crossref
4. R. I. Zainullina, N. G. Bebenin, V. V. Ustinov, D. A. Shulyatev. Phys. Solid State. 59(2), 283 (2017). Crossref
5. N. G. Bebenin, R. I. Zainullina, N. S. Bannikova, V. V. Ustinov, Ya. M. Mukovskii. Phys. Solid State. 50(4), 691 (2008). Crossref
6. N. G. Bebenin, R. I. Zainullina, V. V. Ustinov. JMMM. 321, 682 (2009). Crossref
7. D. Shulyatev, S. Karabashev, A. Arsenov, Ya.Mukovskii, S. Zverkov. J. Cryst.Growth. 237 - 239, 810 (2002). Crossref
8. H. J. McSkimin. In: Physical Acoustics: Principles and Methods. Vol. 1, Part A, p. 272 (Ed. by W. P. Mason). Academic, New York (1964) 532 p.
9. V. Markovich, E. Rozenberg, A. I. Shames, G. Gorodetsky, I. Fita, K. Suzuki, R. Puzniak, D. A. Shulyatev, Ya. M. Mukovskii. Phys. Rev. B. 65, 144402 (2002). Crossref

Similar papers