Nonlinear Phenomena in Multiferroic Nanocapacitors: Joule Heating and Electromechanical Effects

Abstract

We demonstrate an approach for probing nonlinear electromechanical responses in BiFeO(3) 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(3) 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.

Nanoscale mapping of electromechanical response in ionic conductive ceramics with piezoelectric inclusions

“…(1) with the calibration procedure (see the Experimental Section). 28 The linear components for the AlPO 4 and LAGTPO phases correspond to the piezoelectric and electrochemical strain coefficients, respectively. The coefficients for the AlPO 4 and LAGTPO phases are 4.8 and 17.4 pm/V, respectively.…”

Non-piezoelectric effects in piezoresponse force microscopy

“…This can cause an EM response via thermal expansion, which can in turn contribute to the PFM response. In PFM, the surface displacement induced by Joule heating can be expressed as [79,118] ,…”

Unraveling the origins of electromechanical response in mixed-phase bismuth ferrite

“…16 In this Rapid Communication, multiple-harmonic scanning probe microscopy (SPM) and thermodynamic calculations are exploited in a complementary fashion to decipher the origins of enhanced electromechanical response in mixedphase BiFeO 3 thin films. By quantitatively probing the firstand second-order harmonics of strain and dissipation with band-excitation SPM methods, 17,18 competing contributions are decoupled and mapped spatially with nanometer precision. A Rayleigh-type model is then developed to explain the experimental observations.…”

“…This entails that the band-excitation harmonic method can be effectively employed to unravel the respective contributions from these individual mechanisms. 18 Experiments were carried out on a 60-nm-thick BiFeO 3 film grown on LaAlO 3 with a 5 nm LaNiO 3 bottom electrode using band-excitation scanning probe microscopy 17 on an Asylum Research (Cypher) microscope, and first and second harmonic responses were captured as discussed elsewhere. 18 Piezoresponse force microscopy (PFM) was used to investigate the initial domain structure of the mixed-phase film, and is shown elsewhere.…”