Abstract:Here we present a simple and fast method to reliably image polarization charges using charge gradient microscopy (CGM). We collected the current from the grounded CGM probe while scanning a periodically poled lithium niobate single crystal and single-crystal LiTaO 3 thin film on the Cr electrode. We observed current signals at the domains and domain walls originating from the displacement current and the relocation or removal of surface charges, which enabled us to visualize the ferroelectric domains at a scan… Show more
“…In such a case the screening charges of the same polarity will be supplied from the grounded tip to the film surface. Therefore, the current polarity flowing to the tip will be positive for positive domains and negative for negative domains, whereas the CGM current will be negligible for the domains having in-plane direction of polarization 24 .Figure 4Charge gradient microscopy (CGM) imaging of ( b – d ) BFO/NGO and ( f – h ) BFO/LSCO/NGO film heterostructures at different applied tip-forces. ( a ) and ( e ) show the AFM topography of the CGM scan areas, respectively.…”
Here, we report the observation of ferroelectric and ferroelastic nanodomains in (110)-oriented BiFeO3 (BFO) thin films epitaxially grown on low symmetric (100) NdGaO3 (NGO) substrate. We observed long range ordering of ferroelectric 109° stripe nanodomains separated by periodic vertical domain walls in as-grown 130 nm thick BFO films. The effect of La0.67Sr0.33CoO3 (LSCO) conducting interlayer on domain configurations in BFO/NGO film was also observed with relatively short range-ordering of stripe domains due to the modified electrostatic boundary conditions in BFO/LSCO/NGO film. Additional studies on B-site doping of Nb ions in BFO films showed change in the domain structures due to doping induced change in lattice anisotropy while maintaining the stripe domain morphology with 109° domain wall. This long-range array of ferroelectric and ferroelastic domains can be useful for optoelectronic devices and ferroelastic templates for strain coupled artificial magnetoelectric heterostructures.
“…In such a case the screening charges of the same polarity will be supplied from the grounded tip to the film surface. Therefore, the current polarity flowing to the tip will be positive for positive domains and negative for negative domains, whereas the CGM current will be negligible for the domains having in-plane direction of polarization 24 .Figure 4Charge gradient microscopy (CGM) imaging of ( b – d ) BFO/NGO and ( f – h ) BFO/LSCO/NGO film heterostructures at different applied tip-forces. ( a ) and ( e ) show the AFM topography of the CGM scan areas, respectively.…”
Here, we report the observation of ferroelectric and ferroelastic nanodomains in (110)-oriented BiFeO3 (BFO) thin films epitaxially grown on low symmetric (100) NdGaO3 (NGO) substrate. We observed long range ordering of ferroelectric 109° stripe nanodomains separated by periodic vertical domain walls in as-grown 130 nm thick BFO films. The effect of La0.67Sr0.33CoO3 (LSCO) conducting interlayer on domain configurations in BFO/NGO film was also observed with relatively short range-ordering of stripe domains due to the modified electrostatic boundary conditions in BFO/LSCO/NGO film. Additional studies on B-site doping of Nb ions in BFO films showed change in the domain structures due to doping induced change in lattice anisotropy while maintaining the stripe domain morphology with 109° domain wall. This long-range array of ferroelectric and ferroelastic domains can be useful for optoelectronic devices and ferroelastic templates for strain coupled artificial magnetoelectric heterostructures.
“…This phenomenon was observed after switching on the Z + polar surface. Although it does not lead to the formation of the stable isolated domain, it changes spatial distribution of the screening charges [27][28][29] (Fig. 3c).…”
Polarization reversal in ferroelectrics by the tip of scanning probe microscope was intensively studied for last two decades. In addition to classical domain formation and growth, a number of abnormal switching phenomena have been reported. In particularly, it was experimentally and theoretically shown that slow dynamics of the surface screening can control the kinetics of the ferroelectric switching, and result in backswitching and relaxation phenomena. Here, we experimentally demonstrated the practical possibility of the history dependent polarization reversal by the grounded SPM tip. This phenomenon was attributed to the induction of the slowly dissipating charges into the surface, which in the presence of the grounded tip induce polarization reversal. Analytical and numerical electrostatic calculations allow additional insight into the mechanisms of the observed phenomena.
3Piezoresponse force microscopy (PFM) is one of the most popular techniques used for the complex investigations of the ferroelectric materials, allowing visualization of the static ferroelectric domain structures. [1][2][3] At the same time application of the electric field through conductive tip opens a pathway for manipulation with the domain structures on the nanoscale.
4, 5The process of the polarization reversal under the action of the electric field produced by the SPM tip was carefully studied by multiple scientific groups worldwide. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Abnormal switching behaviors, including backswitching, 12,15,[21][22][23] polarization reversal by the "wrong" polarity of the switching voltage 7,11,17,19 and switching along the path of the unbiased SPM tip 18, 24 were reported. These phenomena were attributed to the charge injection 12,15 , screening of the applied electric fields 25 and ferroelastoelectric switching. 7 Despite clear relevance to the qualitative and quantitative interpretation of PFM-derived data on polarization switching, exact origins of the observed phenomena remain poorly understood.Here we experimentally studied the process of the tip-induced polarization reversal in the vicinity of the flat domain wall in the thin periodically poled LiNbO 3 single crystal.Investigations demonstrated unexpected pronounced switching along the path of the grounded SPM tip at distances above 1 μm from the point of the field application. This switching led to the formation of sharp spikes on the initial flat domain wall and nanodomain chains. The obtained results were explained in terms of the spatial distribution of the electric field produced by freshly switched domains and grounded SPM tip. Analytical and numerical calculations of the electric field distribution showed presence of the pronounced induced electric field into the tip surface. Observed phenomenon allows explanation of number of the abnormal switching dynamics reported earlier. 12,15,18 However it gives rise to much wider set 4 of behaviors. For instance, it enables switching (not backswitching) by the grounded tip in th...
“…So, by monitoring the currents at fixed locations on Earth, variations in the charge densities of the passing storm clouds can be mapped. This is almost exactly what Hong et al 1 have done except, rather than map largescale electrical storms, they have invented an analogous technique to determine nanoscale charge variations on the surfaces of inorganic functional materials.…”
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