Ambient temperature high-pressure-induced ferroelectric phase transition in CaMnTi$_2$O$_6$
| Autor: | Ruiz-Fuertes, J., Bernert, T., Zimmer, D., Schrodt, N., Koch-Müller, M., Winkler, B., Bayarjargal, L., Popescu, C., MacLeod, S., Glazyrin, K. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.96.094101 |
| Popis: | The ferroelectric to paraelectric phase transition of multiferroic CaMnTi$_2$O$_6$ has been investigated at high pressures and ambient temperature by second harmonic generation (SHG), Raman spectroscopy, and powder and single-crystal x-ray diffraction. We have found that CaMnTi$_2$O$_6$ undergoes a pressure-induced structural phase transition ($P4_2mc \rightarrow P4_2/nmc$) at $\sim$7 GPa to the same paraelectric structure found at ambient pressure and $T_c$ = 630 K. The continuous linear decrease of the SHG intensity that disappears at 7 GPa and the existence of a Raman active mode at 244 cm$^{-1}$ that first softens up to 7 GPa and then hardens with pressure, are used to discuss the nature of the phase transition of CaMnTi$_2$O$_6$ for which a d$T_c$/d$P = -48$ K/GPa has been found. Neither a volume contraction nor a change of the normalized pressure on the eulerian strain are observed across the phase transition with all the unit-cell volume data following a second order Birch-Murnaghan equation of state with a bulk modulus of $B_0$ = 182.95(2) GPa. Comment: 7 pages, 7 figures |
| Databáze: | arXiv |
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