Elastic and anelastic relaxations associated with phase transitions in EuTiO3

Spalek, Leszek J. and Saxena, Siddharth S. and Panagopoulos, Christos and Katsufuji, Takuro and Schiemer, Jason A. and Carpenter, Michael A. (2014) Elastic and anelastic relaxations associated with phase transitions in EuTiO3. Physical Review Letters, 90 (5). 054119. ISSN 0031-9007 ESSN: 1079-7114 DOI 10.1103/PhysRevB.90.054119

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Abstract

Elastic and anelastic properties of single crystal samples of EuTiO3 have been measured between 10 and 300 K by resonant ultrasound spectroscopy at frequencies in the vicinity of 1 MHz. Softening of the shear elastic constants C44 and 12(C11−C12) by ∼20–30% occurs with falling temperature in a narrow interval through the transition point, Tc=284 K, for the cubic-tetragonal transition. This is accounted for by classical coupling of macroscopic spontaneous strains with the tilt order parameter in the same manner as occurs in SrTiO3. A peak in the acoustic loss occurs a few degrees below Tc and is interpreted in terms of initially mobile ferroelastic twin walls, which rapidly become pinned with further lowering of temperature. This contrasts with the properties of twin walls in SrTiO3, which remain mobile down to at least 15 K. No further anomalies were observed that might be indicative of strain coupling to any additional phase transitions above 10 K. A slight anomaly in the shear elastic constants, independent of frequency and without any associated acoustic loss, was found at ∼140 K. It marks a change from elastic stiffening to softening with falling temperature and perhaps provides evidence for coupling between strain and local fluctuations of dipoles related to the incipient ferroelectric transition. An increase in acoustic loss below ∼80 K is attributed to the development of dynamical magnetic clustering ahead of the known antiferromagnetic ordering transition at ∼5.5 K. Detection of these elastic anomalies serves to emphasize that coupling of strain with tilting, ferroelectric, and magnetic order parameters is likely to be a permeating influence in determining the structure, stability, properties, and behavior of EuTiO3.

Item Type:	Article
Additional Information:	Resonant ultrasound spectroscopy facilities were established in the Department of Earth Sciences, University of Cambridge, through a grant from the Natural Environment Research Council of Great Britain to M.A.C, which is gratefully acknowledged (NE/B505738/1). L.J.S acknowledges the support of the National Science Centre (NCN) through Grant MAESTRO No. DEC-2012/04/A/ST3/00342. C.P. acknowledges financial support in Greece through Grants No. EURYI and No. MEXT-CT-2006-039047 and in Singapore through Award No. NRF-CRP-4-2008-04 of the Competitive Research Programme. S.S.S. thanks Jesus College, Cambridge, KAZTOMPROM and CHT, Tashkent, for support.
Uncontrolled Keywords:	2014AREP; IA68;
Subjects:	03 - Mineral Sciences
Divisions:	03 - Mineral Sciences 08 - Green Open Access
Journal or Publication Title:	Physical Review Letters
Volume:	90
Page Range:	054119
Identification Number:	10.1103/PhysRevB.90.054119
Depositing User:	Sarah Humbert
Date Deposited:	19 Sep 2014 16:09
Last Modified:	02 Nov 2014 00:12
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3122

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