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Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1-xFex)(n)O3n+1-delta Ruddlesden-Popper superstructures

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Title Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1-xFex)(n)O3n+1-delta Ruddlesden-Popper superstructures
 
Creator DOIG, KI
PETERS, JJP
NAWAZ, S
WALKER, D
WALKER, M
LEES, MR
BEANLAND, R
SANCHEZ, AM
MCCONVILLE, CF
PALKAR, VR
LLOYD-HUGHES, J
 
Subject PEROVSKITE STRUCTURE
ROOM-TEMPERATURE
THIN-FILMS
MULTIFERROICS
REFINEMENT
ORIGIN
BIFEO3
FERROELECTRICS
POLARIZATION
SPECTROSCOPY
 
Description Bulk crystals and thin films of PbTi1-xFexO3-delta ( PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pbn+1(Ti1-xFex)(n)O3n+1-delta forms spontaneously during pulsed laser deposition of PTFO on LaAlO3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that n similar or equal to 8 and x similar or equal to 0.5. The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy, and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pbn+1(Ti1-xFex)(n)O3n+1-delta, a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order, and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.
 
Publisher NATURE PUBLISHING GROUP
 
Date 2016-01-15T06:36:18Z
2016-01-15T06:36:18Z
2015
 
Type Article
 
Identifier SCIENTIFIC REPORTS, 5
2045-2322
http://dx.doi.org/10.1038/srep07719
http://dspace.library.iitb.ac.in/jspui/handle/100/17948
 
Language en