Local Probing of Mesoscopic Physics of Ferroelectric Domain Walls
Vasudeva Rao Aravind, A. N. Morozovska, I. Grinberg, S. Bhattacharyya, Y. Li, S. Jesse, S. Choudhury, P. Wu, K. Seal, E. A. Eliseev, S. V. Svechnikov, D. Lee, S… 展开作者
Vasudeva Rao Aravind, A. N. Morozovska, I. Grinberg, S. Bhattacharyya, Y. Li, S. Jesse, S. Choudhury, P. Wu, K. Seal, E. A. Eliseev, S. V. Svechnikov, D. Lee, S. R. Phillpot, L. Q. Chen, A. M. Rappe, V. Gopalan, S. V. Kalinin
备注：
52 pages, 8 figures, 2 appendices, to be submitted to Phys. Rev. B, higher quality figures are available upon request
Domain wall dynamics in ferroic materials underpins functionality of data storage and information technology devices. Using localized electric field of a scanning probe microscopy tip, we experimentally demonstrate a surprisingly rich range of polarization reversal behaviors in the vicinity of the initially flat 180°ferroelectric domain wall. The nucleation bias is found to increase by an order of magnitude from a 2D nucleus at the wall to 3D nucleus in the bulk. The wall is thus significantly ferroelectrically softer than the bulk. The wall profoundly affects switching on length scales of the order of micrometers. The mechanism of correlated switching is analyzed using analytical theory and phase-field modeling. The long-range effect is ascribed to wall bending under the influence of a tip bias well below the bulk nucleation field and placed many micrometers away from the wall. These studies provide an experimental link between the macroscopic and mesoscopic physics of domain walls and atomistic models of nucleation.
Local decomposition at the ferroelectric-antiferroelectric interphase boundaries and formation of mesoscopic structures in lead lanthanum titanate-zirconate solid solutions
An accurate estimate of the ferroelectric polarization in ferroelectric-dielectric stacks is important from a materials science perspective, and it is also crucial for the development of ferroelectric based electron devices. This paper revisits the theory and application of the PUND technique in Metal-Ferroelectric-Dielectric-Metal (MFDM) structures by using analytical derivations and numerical simulations. In an MFDM structure the results of the PUND technique may largely differ from the polarization actually switched in the stack, which in turn is different from the remnant polarization of t…
Reducing the dimensions of ferroelectric materials down to the nanoscale has strong implications on the ferroelectric polarization pattern and on the ability to switch the polarization. As the size of ferroelectric domains shrinks to nanometer scale, the heterogeneity of the polarization pattern becomes increasingly pronounced, enabling a large variety of possible polar textures in nanocrystalline and nanocomposite materials. Critical to the understanding of fundamental physics of such materials and hence their applications in electronic nanodevices, is the ability to investigate their ferroel…
Microwave measurements have recently been successfully applied to measure ferroelectric materials on the nanoscale, including detection of polarization switching and ferroelectric domain walls. Here we discuss the question whether scanning probe microscopy (SPM) operating at microwave frequency can identify the changes associated with the soft phonon dynamics in a ferroic. The analytical expressions for the electric potential, complex impedance and dielectric losses are derived and analyzed, since these physical quantities are linked to experimentally-measurable properties of the ferroic. As a…
Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long term development for reducing the sizes of devices, the preparation of ferroelectric materials and devices are entering nanometer-scale regime. Accordingly, to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it has been generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale r…
We employ electron paramagnetic resonance (EPR) of the spin probe Mn2+ to study the paraelectric ferroelectric transition in DMAMnF and Mn2 doped DMZnF, which are considered to be model metal organic frameworks (MOF) with a Pb free perovskite architecture. In DMAMnF, we study the variation of the Mn2+ EPR line shape and intensity at the X-band (9.4 GHz) and over 80 to 300 K, and we show the absence of magnetoelectric coupling at the ferroelectric transition. At the antiferromagnetic transition in DMMnF, we detect a magnetoelectric coupling caused by weak ferromagnetism in the AFM phase. In DMZ…
The structure of 180-degree uncharged rotational domain wall in a multiaxial ferroelectric film is studied within the framework of analytical Landau-Ginzburg-Devonshire (LGD) approach. The Finite Element Modelling (FEM) is used to solve numerically the system of the coupled nonlinear Euler-Lagrange (EL) differential equations of the second order for two components of polarization. We show that the structure of the domain wall and corresponding (meta)stable phase of the film are controlled by a single master parameter, dimensionless ferroelectric anisotropy μ. We fitted the static profile of a …
Raman Spectroscopic measurements are carried out to investigate the structural phase transitions as a function of composition in modified sodium niobate [(1-x) NaNbO3-xBaTiO3:NNBTx] for x=0.0 to 0.15 at room temperature. The characteristic antiferroelectric modes at around 93.4 and 123.6cm-1alongwith a mode at 155.5 cm-1were found to disappear across the structural phase transition from antiferroelectric orthorhombic phase (Pbcm) to ferroelectric orthorhombic phase (Pmc21) phase for x>0.02. The redistribution of intensities and positions of the Raman lines in bending (150-350 cm-1) and stretch…
Ferroelectric domain walls have emerged as one of the most fascinating objects in condensed matter physics due to the broad variability of functional behaviors they exhibit. However, the vast majority of domain walls studies have been focused on bias-induced dynamics and transport behaviors. Here, we introduce the scanning probe microscopy approach based on piezoresponse force microscopy (PFM) with a dynamically heated probe, combining local heating and local biasing of the material. This approach is used to explore the thermal polarization dynamics in soft Sn2P2S6 ferroelectrics, and allows f…
Understanding the dynamic behavior of the domain structure is critical to the design and application of super-elastic freestanding ferroelectric thin films. The phase-field simulation is currently a powerful tool for observing, exploring, and revealing domain switching behavior and phase transition in ferroelectric materials at the mesoscopic scale. The present review summarizes the recent progress of phase-field methods in the theoretical interpretation, mechanical response, and domain structure evolution of freestanding ferroelectric thin films, wrinkled structures, and nano-springs. Further…
Combination of local heating and biasing at the tip-surface junction in temperature-assisted piezoresponse force microscopy (tPFM) opens the pathway for probing local temperature induced phase transitions in ferroics, exploring the temperature dependence of polarization dynamics in ferroelectrics, and potentially discovering coupled phenomena driven by strong temperature- and electric field gradients. Here, we analyze the signal formation mechanism in tPFM and explore the interplay between thermal- and bias-induced switching in model ferroelectric materials. We further explore the contribution…
The van der Waals layered material CuInP2S6 features interesting functional behavior, including the existence of four uniaxial polarization states, polarization reversal against the electric field through Cu ion migration, a negative-capacitance regime, and reversible extraction of Cu ions. At the heart of these characteristics lies the high mobility of Cu ions, which also determines the spontaneous polarization. Therefore, Cu migration across the lattice results in unusual ferroelectric behavior. Here, we demonstrate how the interplay of polar and ionic properties provides a path to ionically…
Pyroelectric thermo-wave probing of BaZr0.2Ti0.8O3 ceramics
Institute of Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院物理研究所）；Frantsevich Institute for Problems in Materials Science, National Academy of Sciences of Ukraine（乌克兰国家科学院弗兰采维奇材料科学问题研究所）；V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院瓦·拉沙卡罗夫半导体物理研究所）；Institute of Physics, Czech Academy of Sciences（捷克科学院物理研究所）
Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties. While optical second harmonic generation (SHG) has long been utilized in ferroelectric studies, its capability for probing complex polar materials has yet to be fully realized. Here, we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope, and demonstrate its application for a model system of (K,Na)NbO3 single crystals. Supervised model fitting analysis produces comprehensive info…
Domain Nucleation and Hysteresis Loop Shape in Piezoresponse Force Spectroscopy
压电响应力显微镜（Piezoresponse Force Microscopy）中的机电磁滞回线测量已经成为探测纳米尺度上的铁电开关行为的强大技术。PFS数据的解释需要建立域参数和PFM信号之间的关系。在这里，我们分析了开关过程中使用修改后的点电荷模型的电场的提示。选择电荷值和位置，使得其电场等势面以确定的曲率半径再现尖端。利用线性弹性理论，推导了半椭球畴大小与PFM信号大小的关系。确定了畴形核对压电响应迟滞回线的作用。
University of California, Berkeley（加州大学伯克利分校）；Kepler Computing（开普勒计算公司）；Rice Advanced Materials Institute, Rice University（莱斯大学先进材料研究所）；Rice University（莱斯大学）；Department of Engineering Physics, University of California, Berkeley（加州大学伯克利分校工程物理系）；Department of Physics, University of California, Berkeley（加州大学伯克利分校物理系）
Highly sensitive simple homodyne phase detector for ultrasonic pulse-echo measurements
我们设计并制造了一台现代化的多功能研究级仪器，用于在实验室条件下对各种材料的弹性性能进行超声脉冲回波探测。该仪器的核心在于AD 8302微芯片：ADI公司的增益和相位检波器。为了构建该设备，我们已经实现了一个示意图，利用零差原理的信号处理，而不是传统的超外差方法。该设计允许在$0-360^\circ$的整个范围内以高精度和线性度测量相移。该系统结构简单，使用方便;它使广泛的研究人员可以轻松地进行超声测量。通过在频率为$\sim$ 40 MHz下测量KTa $_{0.92}$ Nb $_{0.08}$ O $_{3}$（KTN）单晶中的超声速度和衰减的温度依赖性来测试。测试在铁电转变附近进行，其中速度和衰减的大变化要求具有突出特性的检测器。所描述的检测器具有宽的动态范围，并且允许在铁电转变的整个温度范围内的单次运行中进行测量，而不是仅在先前可用的有限间隔中进行测量。此外，由于增益测量的宽动态范围和高灵敏度，该仪器能够揭示与KTN晶体的铁电转变的发展相关的先前无法分辨的特征。
