A5072295559- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Ultrasonics and Acoustic Wave Propagation
- Acoustic Wave Resonator Technologies
- Advanced Condensed Matter Physics
- Ultrasound Imaging and Elastography
- Theoretical and Computational Physics
- Solid-state spectroscopy and crystallography
- Physics of Superconductivity and Magnetism
- Cold Atom Physics and Bose-Einstein Condensates
- Chalcogenide Semiconductor Thin Films
- Dielectric properties of ceramics
- Crystal Structures and Properties
- 2D Materials and Applications
- Magneto-Optical Properties and Applications
- Optical properties and cooling technologies in crystalline materials
- Magnetic properties of thin films
- Geophysics and Sensor Technology
- Magnetic and transport properties of perovskites and related materials
- Glass properties and applications
- Magnetism in coordination complexes
- Non-Destructive Testing Techniques
- Quantum, superfluid, helium dynamics
- Earthquake Detection and Analysis
- High-pressure geophysics and materials
University of California, Berkeley
2024
Lawrence Berkeley National Laboratory
2024
Material Sciences (United States)
2024
University of Glasgow
2018-2022
Stabilization of topological spin textures in layered magnets has the potential to drive development advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation beyond skyrmion a two-dimensional magnet system remains challenging. Here, we demonstrate introduction magnetic iron atoms between van der Waals gap magnet, Fe3GaTe2, modify local anisotropic interactions. Consequently, present direct observations order-disorder lattices transition. In...
The acoustic phonons in the organic-inorganic lead halide perovskites have been reported to anomalously short lifetimes over a large part of Brillouin zone. resulting shortened mean free paths implicated as origin low thermal conductivity. We apply neutron spectroscopy show that same phonon energy linewidth broadening (corresponding lifetimes) occurs fully inorganic ${\mathrm{CsPbBr}}_{3}$ by comparing results on ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbCl}}_{3}$. investigate critical...
Mn:PIN-PMN-PT piezocrystal is investigated to determine whether its enhanced energy density makes it a candidate transducer material for power ultrasonics applications. To this end, the electromechanical and vibrational characteristics of simple configuration bolted Langevin (BLT) then an ultrasonic surgical device, both incorporating piezocrystal, are compared with same configurations conventional hard PZT piezoceramic commonly used in high-power transducers. The properties determined using...
The impact of Pb on the environment and human health recent restrictions its use in electronic devices are generating demand for Pb-free piezoelectric materials. Examples now available commercially, but full elastic-piezoelectric-dielectric (EPD) matrices needed device design, including over a range operating conditions, have not yet been published. standard IEEE EPD matrix measurement method needs four sample geometries, making it inconvenient increasing errors. Here, we present an...
Ba$_{3}$NbFe$_{3}$Si$_{2}$O$_{14}$ (langasite) is structurally and magnetically single domain chiral with the magnetic helicity induced through competing symmetric exchange interactions. Using neutron scattering, we show that spin-waves in antiferromagnetic langasite display directional anisotropy. On applying a time reversal symmetry breaking field along $c$-axis, spin wave energies differ when sign reversed for either momentum transfer $\pm$ $\vec{Q}$ or applied $\mu_{0}$H. When within...
Spin density waves, based on modulated local moments, are usually associated with metallic materials, but have recently been reported in insulators which display coupled magnetic and structural order parameters. We discuss one such example, the multiferroic Cu$_3$Nb$_2$O$_8$, is to undergo two phase transitions, first a spin wave at $T_N \approx 26.5K$, then helicoidal structure an electric polarization below $T_2 24K$ [R. D. Johnson, et al., Phys. Rev. Lett., 107, 137205 (2011)] breaks...
$\mathrm{Pb}{\mathrm{Fe}}_{1/2}{\mathrm{Nb}}_{1/2}{\mathrm{O}}_{3}$ (PFN) is a relaxor ferroelectric (${T}_{c}\ensuremath{\sim}400\phantom{\rule{0.16em}{0ex}}\mathrm{K}$) consisting of magnetic ${\mathrm{Fe}}^{3+}$ ($S=\frac{5}{2}, L\ensuremath{\approx}0$) ions disordered throughout the lattice and hosts spin-glass phase at low temperatures built from spatially isolated clusters ions, termed ``cluster glass'' [Kleemann et al., Phys. Rev. Lett. 105, 257202 (2010)]. We apply neutron scattering...
Abstract Relaxor-ferroelectrics display exceptional dielectric properties resulting from the underlying random dipolar fields induced by strong chemical inhomogeneity. An unusual structural aspect of relaxors is a skin-effect where near-surface region in single crystals exhibit structures and critical phenomena that differ bulk. Relaxors are unique this skin effect extends over macroscopic lengthscale ∼100 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow>...
A quantum critical point (QCP) represents a continuous phase transition at absolute zero. At the QCP of an unconventional superconductor, enhanced superconducting temperature and magnetic fluctuations strength are often observed together, indicating magnetism-mediated superconductivity. This raises question whether in other degrees freedom, such as charge, could similarly boost However, because charge is frequently intertwined with magnetism, isolating understanding its specific role Cooper...
Optical phonon engineering through nonlinear effects has been utilized in ultrafast control of material properties. However, optical phonons typically exhibit rapid decay due to strong mode-mode couplings, limiting their effectiveness temperature or frequency sensitive applications. In this study, we report the observation long-lived spontaneous formation combs van der Waals CrXTe$_3$ (X=Ge, Si) using high-resolution Raman scattering. Unlike conventional phonons, highest $A_g$ mode...
Employing inelastic X-ray scattering and neutron techniques, we observed nematic magnetic phase transitions with distinct characters in K$_{5}$Fe$_{4}$Ag$_{6}$Te$_{10}$. Upon cooling, the order undergoes a strongly first-order transition followed by second-order at $T_{\textrm{N}}$ $\approx$ 34.6 K. The temperature difference between these two is $\sim$ 1 phenomenon can be attributed to distinctive preemptive Ising-nematic transition, characteristic unique quasi-two-dimensional scenario...
Mn:PIN-PMN-PT piezocrystals are under consideration for potential use in miniaturised ultrasonic scalpels robotic minimally-invasive surgery where small size and light weight may be advantageous. Electromechanical coupling coefficient k > 0.9 both [001] [011] poled was calculated, confirming the well-recognized higher efficiency of this material when compared to standard piezoceramics. Novel transducer design strategies have been explored, outcomes discussed. The introduction components with...
The full piezoelastoelectric matrices for 4mm Mn: PIN-PMN-PT piezocrystal (TRS Technologies, PA, USA) and 6mm piezoceramic PIC 700 (PI Ceramics, Lederhose, Germany) have been obtained through resonant ultrasound spectroscopy combined with an optimisation algorithm based on the Levenberg-Marquardt (LM) Nelder-Mead (NM) approaches using exact cube samples. Both methods found to converge, differences in solutions are reported. Laser Doppler vibrometry (LDV) has used validate material...
The negative environmental impact of Pb has led to an increased demand for Pb-free electronics. This is particularly important in ultrasonic transducers where Pb-based piezoelectric materials, primarily ceramic PZT, are the dominant choice. Naturally materials become a viable option, performance must match that current standard. However, present comparison methods and figures merit based on specific use cases which can lead disparate results. In work described here, new measure developed...
Mn:PIN-PMN-PT plates: [011]-poled (mm2 symmetry, d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">32</inf> -mode) were characterized at high-power excitation levels and different temperatures. A bespoke measurement system was utilized to acquire the electrical impedance resonance. Results have shown that resonant frequency/anti-resonant frequency downshifts with increasing driving voltage temperature.