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Nonlinear Phenomena in Multiferroic Nanocapacitors: Joule Heating and Electromechanical Effects
Kim, Yunseok,Kumar, Amit,Tselev, Alexander,Kravchenko, Ivan I.,Han, Hee,Vrejoiu, Ionela,Lee, Woo,Hesse, Dietrich,Alexe, Marin,Kalinin, Sergei V.,Jesse, Stephen American Chemical Society 2011 ACS NANO Vol.5 No.11
<P>We demonstrate an approach for probing nonlinear electromechanical responses in BiFeO<SUB>3</SUB> thin film nanocapacitors using half-harmonic band excitation piezoresponse force microscopy (PFM). Nonlinear PFM images of nanocapacitor arrays show clearly visible clusters of capacitors associated with variations of local leakage current through the BiFeO<SUB>3</SUB> film. Strain spectroscopy measurements and finite element modeling point to significance of the Joule heating and show that the thermal effects caused by the Joule heating can provide nontrivial contributions to the nonlinear electromechanical responses in ferroic nanostructures. This approach can be further extended to unambiguous mapping of electrostatic signal contributions to PFM and related techniques.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-11/nn203342v/production/images/medium/nn-2011-03342v_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn203342v'>ACS Electronic Supporting Info</A></P>
Interplay of Octahedral Tilts and Polar Order in BiFeO<sub>3</sub> Films
Kim, Young‐,Min,Kumar, Amit,Hatt, Alison,Morozovska, Anna N.,Tselev, Alexander,Biegalski, Michael D.,Ivanov, Ilya,Eliseev, Eugene A.,Pennycook, Stephen J.,Rondinelli, James M.,Kalinin, Sergei V. WILEY‐VCH Verlag 2013 ADVANCED MATERIALS Vol.25 No.17
<P><B>Heterointerface stabilization of a distinct nonpolar BiFeO<SUB>3</SUB> phase</B> occurs simultaneously with changes in octahedral tilts. The resulting phase arises via suppression of polarization by a structural order parameter and can thus be identified as anti‐ferroelectric (Fe displacements – bottom panel). The phase is metastable and can be switched into a polar ferroelectric state (top panel) under an applied electric bias.</P>
Yang, Sang Mo,Strelcov, Evgheni,Paranthaman, M. Parans,Tselev, Alexander,Noh, Tae Won,Kalinin, Sergei V. American Chemical Society 2015 NANO LETTERS Vol.15 No.2
<P>Scanning probe microscopy (SPM) is a powerful tool to investigate electrochemistry in nanoscale volumes. While most SPM-based studies have focused on reactions at the tip–surface junction, charge and mass conservation requires coupled and intrinsically nonlocal cathodic and anodic processes that can be significantly affected by ambient humidity. Here, we explore the role of water in both cathodic and anodic processes, associated charge transport, and topographic volume changes depending on the polarity of tip bias. The first-order reversal curve current–voltage technique combined with simultaneous detection of the sample topography, referred to as FORC-IVz, was applied to a silver solid ion conductor. We found that the protons generated from water affect silver ionic conduction, silver particle formation and dissolution, and mechanical integrity of the material. This work highlights the dual nature (simultaneously local and nonlocal) of electrochemical SPM studies, which should be considered for comprehensive understanding of nanoscale electrochemistry.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-2/nl5040286/production/images/medium/nl-2014-040286_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5040286'>ACS Electronic Supporting Info</A></P>