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Fernandez-Posada CM, Cochard C, Gregg JM, Whatmore RW, Carpenter MA. Order-disorder, ferroelasticity and mobility of domain walls in multiferroic Cu-Cl boracite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:095402. [PMID: 33202391 DOI: 10.1088/1361-648x/abcb0f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Domain walls in Cu-Cl boracite develop as a consequence of an improper ferroelastic, improper ferroelectric transition, and have attracted close interest because some are conductive and all can be mechanically written and repositioned by application of an electric field. The phase transition and its associated dynamical properties have been analysed here from the perspective of strain and elasticity. Determination of spontaneous strains from published lattice parameter data has allowed the equilibrium long-range order parameter for F [Formula: see text]3c → Pca21 to be modelled simply as being close to the order-disorder limit. High acoustic loss in the cubic phase, revealed by resonant ultrasound spectroscopy, is consistent with the presence of dynamical microdomains of the orthorhombic structure with relaxation times in the vicinity of ∼10-5-10-6 s. Low acoustic loss in the stability field of the orthorhombic structure signifies, on the other hand, that ferroelastic twin walls which develop as a consequence of the order-disorder process are immobile on this time scale. A Debye loss peak accompanied by ∼1% elastic stiffening at ∼40 K is indicative of some freezing of defects which couple with strain or of some more intrinsic freezing process. The activation energy of ⩾∼0.01-0.02 eV implies a mechanism which could involve strain relaxation clouds around local ferroelectric dipoles or freezing of polarons that determine the conductivity of twin walls.
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Affiliation(s)
- C M Fernandez-Posada
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom
| | - C Cochard
- Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - J M Gregg
- Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - R W Whatmore
- Department of Chemistry, University College Cork, Cork, Ireland
- Department of Materials, Faculty of Engineering, Imperial College London, London, SW7 2AZ, United Kingdom
| | - M A Carpenter
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom
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Saha S, Cao BC, Motapothula M, Cong CX, Sarkar T, Srivastava A, Sarkar S, Patra A, Ghosh S, Ariando, Coey JMD, Yu T, Venkatesan T. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study. Sci Rep 2016; 6:36859. [PMID: 27845368 PMCID: PMC5109287 DOI: 10.1038/srep36859] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/20/2016] [Indexed: 11/22/2022] Open
Abstract
Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.
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Affiliation(s)
- Surajit Saha
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Bing-Chen Cao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
| | - M Motapothula
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Chun-Xiao Cong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
| | - Tarapada Sarkar
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Amar Srivastava
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Soumya Sarkar
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Abhijeet Patra
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, National University of Singapore, 117456, Singapore
| | - Siddhartha Ghosh
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore
| | - Ariando
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - J M D Coey
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College, Dublin, Ireland
| | - Ting Yu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
| | - T Venkatesan
- NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.,Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, National University of Singapore, 117456, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
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Salje EKH, Alexe M, Kustov S, Weber MC, Schiemer J, Nataf GF, Kreisel J. Direct observation of polar tweed in LaAlO3. Sci Rep 2016; 6:27193. [PMID: 27250525 PMCID: PMC4890045 DOI: 10.1038/srep27193] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/16/2016] [Indexed: 12/03/2022] Open
Abstract
Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 μm) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS). PFM and RPS observations prove unequivocally that electrical polarity exists inside the tweed patterns of LaAlO3. The local piezoelectric effect varies greatly within the tweed patterns and reaches magnitudes similar to quartz. The patterns were mapped by the shift of the Eg soft-mode frequency by Raman spectroscopy.
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Affiliation(s)
- Ekhard K H Salje
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.,Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | - Marin Alexe
- University of Warwick, Department of Physics, Coventry CV4 7AL, W Midlands, England
| | - Sergey Kustov
- Universite des Illes Balears, Department Fisica, E-07122 Palma De Mallorca, Spain
| | - Mads C Weber
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.,Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg
| | - Jason Schiemer
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | - Guillaume F Nataf
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.,Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.,SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Jens Kreisel
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.,Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg
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Zhang Z, Koppensteiner J, Schranz W, Carpenter MA. Anelastic loss behaviour of mobile microstructures in SrZr(1-x)Ti(x)O3 perovskites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:295401. [PMID: 21399303 DOI: 10.1088/0953-8984/22/29/295401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Anelastic loss mechanisms associated with phase transitions in SrZr(1-x)Ti(x)O(3) perovskites (x = 0.375, 0.450, 0.550, 0.775) have been investigated by dynamic mechanical analysis between 128 and 723 K at frequencies of 0.1-50 Hz. Distinctive patterns of changes in the elastic moduli due to octahedral tilting transitions correlate closely with data for the shear modulus obtained previously by resonant ultrasound spectroscopy at high frequencies (∼0.5 MHz). The I4/mcm <--> Imma transition is first order and has a characteristic minimum in the shear modulus and Young's modulus. For x = 0.450 and 0.550, a dissipation peak occurs at the transition temperature, the maximum of which varies with frequency according to a power law relationship of the form tanδ = Af(n), with n≈ - 0.3. Debye-like dissipation peaks in the stability field of the Imma structure at x = 0.375 have a frequency and temperature dependence consistent with twin wall pinning by defects with an activation energy ∼ 184 kJ mol(-1). These results indicate that there is diversity of pinning and relaxation processes for transformation twin walls and interfaces in different perovskites with I4/mcm, Imma and Pnma structures.
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Affiliation(s)
- Zhiying Zhang
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
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