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51 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I15-Extreme Conditions	Domain switching and shear-mode piezoelectric response induced by cross-poling in polycrystalline ferroelectrics D. A. Hall , L. Daniel , M. Watson , A. Condie , T. P. Comyn , A. K. Kleppe , P. J. Withers Journal Of Applied Physics 136 DOI: 10.1063/5.0238994 Diamond Proposal Number(s): [8699] Open Access Show Abstract ▼ Abstract: The mechanisms contributing to the electromechanical response of piezoelectric ceramics in shear mode have been investigated using high energy synchrotron x-ray diffraction. Soft lead zirconate titanate ceramic specimens were subjected to an electric field in the range 0.2 to 3.0 MV m-1, perpendicular to that of the initial poling direction, while XRD patterns were recorded in transmission. At low electric field levels, the axial strains remained close to zero but a significant shear strain occurred due to the reversible shear-mode piezoelectric coefficient. Both the axial and shear strains increased substantially at higher field levels due to irreversible ferroelectric domain switching. Eventually, the shear strain decreased again as the average remanent polarization became oriented towards the electric field direction. The lattice strain and domain orientation distributions follow the form of the total strain tensor, enabling the domain switching processes to be monitored by the rotation of the principal strain axis. Reorientation of this axis towards the electric field direction occurred progressively above 0.6 MV m-1, while the angle of rotation increased from 0° to approximately 80° at the maximum field of 3.0 MV m-1. A strong correlation was established between the effective strains associated with different crystallographic directions, which was attributed to the effects of elastic coupling between grains in the polycrystal.	Nov 2024
I10-Beamline for Advanced Dichroism - scattering	Using magneto-optical effects in soft x-ray reflectivity to study current driven magnetisation reversal Kiranjot Dhaliwal , Raymond Fan , Razan O. M. Aboljadayel , David M. Burn , Kalel Alsaeed , Aidan T. Hindmarch , Paul Steadman Japanese Journal Of Applied Physics DOI: 10.35848/1347-4065/ad760b Diamond Proposal Number(s): [31755] Open Access Show Abstract ▼ Abstract: The soft X-ray reflectivity technique is frequently utilized for studying magnetization reversal in thin films due to its elemental and depth sensitivity. The characteristic hysteresis loops measured with this technique are dependent on both the magnetization direction in magnetic materials and the incident soft X-ray polarization. In this note, we have discussed these magneto-optical effects in soft X-ray reflectivity measurements. These effects can be exploited to probe magnetization reversal mechanisms driven by stimuli beyond conventional means of magnetic field. To demonstrate this, we have presented our investigations on current-induced magnetization switching in ferromagnet/heavy metal (FM/HM) heterostructures.	Sep 2024
I15-Extreme Conditions	In situ electric field-dependent structural changes in (Ba,Ca)(Zr,Ti)O3 with varying grain size Michel Kuhfuß , Juliana G. Maier , David A. Hall , Bingying Xie , Annette K. Kleppe , Alexander Martin , Ken-Ichi Kakimoto , Neamul H. Khansur , Kyle G. Webber Journal Of Applied Physics 135 DOI: 10.1063/5.0203652 Diamond Proposal Number(s): [31704] Open Access Show Abstract ▼ Abstract: The functional properties of piezoelectric ceramic materials, such as barium titanate, are highly dependent on grain size. Lead-free polycrystalline Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) samples were prepared with a combination of the hydrothermal method and spark plasma sintering to achieve grain sizes from 100 nm to 10 μm by varying the maximum sintering temperature. In this range, a transition from a nearly linear dielectric to a ferroelectric response can be seen in macroscopic electromechanical measurements, demonstrating the importance of grain size on functional properties in BCZT. Furthermore, in situ electric field-dependent synchrotron x-ray diffraction measurements were performed to quantify the intrinsic and extrinsic strain contributions and their variations with grain size. At lower grain sizes, the data revealed a significant loss of extrinsic contributions in the piezoelectric behavior, limiting the response to intrinsic contribution associated with lattice strain. For BCZT, a critical grain size between approximately 0.08 and 0.18 μm is proposed, below which no piezoelectric response was observed.	May 2024
I15-Extreme Conditions	Palladium at high pressure and high temperature: A combined experimental and theoretical study S. R. Baty , L. Burakovsky , D. J. Luscher , S. Anzellini , D. Errandonea Journal Of Applied Physics 135 DOI: 10.1063/5.0179469 Diamond Proposal Number(s): [28469] Open Access Show Abstract ▼ Abstract: Palladium is one of the most important technological materials, yet its phase diagram remains poorly understood. At ambient conditions, its solid phase is face-centered cubic (fcc). However, another solid phase of Pd, body-centered cubic (bcc), was very recently predicted in two independent theoretical studies to occur at high pressures and temperatures. In this work, we report an experimental study on the room-temperature equation of state (EOS) of Pd to a pressure of 80 GPa, as well as a theoretical study on the phase diagram of Pd including both fcc-Pd and bcc-Pd. Our theoretical approach consists in ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries. We obtain the melting curves of both fcc-Pd and bcc-Pd and an equation for the fcc–bcc solid–solid phase transition boundary as well as the thermal EOS of Pd which is in agreement with experimental data and QMD simulations. We uncover the presence of another solid phase of Pd on its phase diagram, namely, random hexagonal close-packed (rhcp), and estimate the location of the rhcp-bcc solid–solid phase transition boundary and the rhcp–fcc–bcc triple point. We also discuss the topological similarity of the phase diagrams of palladium and silver, the neighbor of Pd in the periodic table. We argue that Pd is a reliable standard for shock-compression studies and present the analytic model of its principal Hugoniot in a wide pressure range.	Feb 2024
	Effect of Ag-addition on the thermoelectric properties of Cu12Sb4S13 tetrahedrite Umasankar Rout , Sahil Tippireddy , Naina Kumari , Titas Dasgupta , Ramesh Chandra Mallik Journal Of Applied Physics 134 DOI: 10.1063/5.0184270 Show Abstract ▼ Abstract: Tetrahedrite, Cu12Sb4S13, an eco-friendly thermoelectric material with earth-abundant and low-cost constituents, has garnered global interest. This study investigated the thermoelectric characteristics of Ag-added tetrahedrites, which were prepared through solid-state synthesis and subsequently hot-pressed. The minimal temperature dependence of the transport coefficient indicated the presence of strong electron–phonon coupling in the samples. It was observed that Ag addition in tetrahedrite could successfully scatter acoustic phonons, reducing the lattice thermal conductivity while minimally affecting the power factor. The enhanced anharmonicity induced by Ag addition is the primary cause of reduced lattice thermal conductivity. Raman spectroscopy data showed that Ag addition could weaken the Sb–S bond, further supporting the previous argument. Consequently, the lattice thermal conductivity was lowered to ∼0.27 W m−1 K−1 and obtained for the composition Ag0.025 added Cu11.975Sb4S13. A relatively high power factor of ∼1.3 mW m−1 K−2 was obtained for the same composition. Owing to the lowest total thermal conductivity ∼1.09 W m−1 K−1, the sample with composition Ag0.025 added Cu11.975Sb4S13 showed the highest thermoelectric figure of merit of 0.87 at 738 K.	Dec 2023
I06-Nanoscience (XPEEM)	The single power law relationship between coercivity and width in pointed composite element magnetic barcodes P. J. Newton , S. M. Masur , N. B. Devlin , M. Ghidini , D. Backes , F. Maccherozzi , A. A. Pacheco-Pumaleque , C. H. W. Barnes Journal Of Applied Physics 134 DOI: 10.1063/5.0166821 Diamond Proposal Number(s): [24373] Open Access Show Abstract ▼ Abstract: Pointed magnetic elements are introduced as an improvement upon rectangular strips currently employed in composite element magnetic barcodes. The coercivity of these elements, as measured using the magneto-optic Kerr effect, is found to strictly adhere to a single power law relationship with the element width, where the power law exponent is dependent on the length of the pointed region and takes values between − 0.98 and − 0.91. The steeper gradients here, along with the absence of the crossover region seen in rectangular devices, present these structures as a strict improvement in terms of potential device applications. These improvements are found to be present for all structures where the pointed region is as long as, or longer than, the magnetic element is wide. The remanent magnetization configuration, imaged using photo-emission microscopy with contrast from x-ray magnetic circular dichroism (XMCD-PEEM), is compared to the results of micromagnetic simulations. It is found to cant inward in the pointed section of the strip, aligning with the edges of the point, pinning the magnetization and giving a consistent magnetization reversal behavior for all element widths investigated.	Oct 2023
I15-Extreme Conditions	A comparison of different Fourier transform procedures for analysis of diffraction data from noble gas fluids J. E. Proctor , C. G. Pruteanu , B. Moss , M. A. Kuzovnikov , G. J. Ackland , C. W. Monk , S. Anzellini Journal Of Applied Physics 134 DOI: 10.1063/5.0161033 Diamond Proposal Number(s): [28469] Show Abstract ▼ Abstract: A comparison is made between the three principal methods for the analysis of neutron and x-ray diffraction data from noble gas fluids by direct Fourier transform. All three methods (standard Fourier transform, Lorch modification, and Soper–Barney modification) are used to analyze four different sets of diffraction data from noble gas fluids. The results are compared to the findings of a full-scale real-space structure determination, namely, Empirical Potential Structure Refinement. Conclusions are drawn on the relative merits of the three Fourier transform methods, what information can be reliably obtained using each method, and which method is most suitable for the analysis of different kinds of diffraction data. The mathematical validity of the Lorch method is critically analyzed.	Sep 2023
B18-Core EXAFS I10-Beamline for Advanced Dichroism - scattering	Absence of spin-mixed states in ferrimagnet Yttrium iron garnet D. Cheshire , P. Bencok , D. Gianolio , G. Cibin , V. K. Lazarov , Gerrit Van Der Laan , S. A. Cavill Journal Of Applied Physics 132, 103902 DOI: 10.1063/5.0099477 Diamond Proposal Number(s): [24930, 22629] Open Access Show Abstract ▼ Abstract: The spectroscopic g-factor of epitaxial thin film Yttrium Iron Garnet (YIG) has been studied using a combination of ferromagnetic resonance spectroscopy and x-ray magnetic circular dichroism. The values obtained by the two techniques are found, within experimental error, to be in agreement using Kittel’s original derivation for the g-factor. For an insulating material with an entirely Fe3+ configuration, a spin mixing correction to Kittel’s derivation of the spectroscopic g-factor, as recently shown by Shaw et al. [Phys. Rev. Lett. 127, 207201 (2021)] for metallic systems, is not required and demonstrates that the spin mixing parameter is small in YIG due to negligible spin–orbit coupling.	Sep 2022
I09-Surface and Interface Structural Analysis	Evaluation of the thermal stability of TiW/Cu heterojunctions using a combined SXPS and HAXPES approach C. Kalha , M. Reisinger , P. K. Thakur , T.-L. Lee , S. Venkatesan , M. Isaacs , R. G. Palgrave , J. Zechner , M. Nelhiebel , A. Regoutz Journal Of Applied Physics 131 DOI: 10.1063/5.0086009 Diamond Proposal Number(s): [24248] Open Access Show Abstract ▼ Abstract: Power semiconductor device architectures require the inclusion of a diffusion barrier to suppress or at best prevent the interdiffusion between the copper metallization interconnects and the surrounding silicon substructure. The binary pseudo-alloy of titanium–tungsten (TiW), with >70 at. % W, is a well-established copper diffusion barrier but is prone to degradation via the out-diffusion of titanium when exposed to high temperatures (≥400 ∘C). Here, the thermal stability of physical vapor deposited TiW/Cu bilayer thin films in Si/SiO2(50 nm)/TiW(300 nm)/Cu(25 nm) stacks were characterized in response to annealing at 400 ∘C for 0.5 h and 5 h, using a combination of soft and hard x-ray photoelectron spectroscopy and transmission electron microscopy. Results show that annealing promoted the segregation of titanium out of the TiW and interdiffusion into the copper metallization. Titanium was shown to be driven toward the free copper surface, accumulating there and forming a titanium oxide overlayer upon exposure to air. Annealing for longer timescales promoted a greater out-diffusion of titanium and a thicker oxide layer to grow on the copper surface. However, interface measurements suggest that the diffusion is not significant enough to compromise the barrier integrity, and the TiW/Cu interface remains stable even after 5 h of annealing.	Apr 2022
I05-ARPES	Observation of the critical state to multiple-type Dirac semimetal phases in KMgBi D. F. Liu , L. Y. Wei , C. C. Le , H. Y. Wang , X. Zhang , N. Kumar , C. Shekhar , N. B. M. Schröter , Y. W. Li , D. Pei , L. X. Xu , P. Dudin , T. K. Kim , C. Cacho , J. Fujii , I. Vobornik , M. X. Wang , L. X. Yang , Z. K. Liu , Y. F. Guo , J. P. Hu , C. Felser , S. S. P. Parkin , Y. L. Chen Journal Of Applied Physics 129 DOI: 10.1063/5.0045466 Diamond Proposal Number(s): [18005] Open Access Show Abstract ▼ Abstract: Dirac semimetals are classified into different phases based on the types of Dirac fermions. Tuning the transition among different types of Dirac fermions in one system remains a challenge. Recently, KMgBi was predicted to be located at a critical state in which various types of Dirac fermions can be induced owing to the existence of a flatband. Here, we carried out systematic studies on the electronic structure of KMgBi single crystals by combining angle-resolve photoemission spectroscopy and scanning tunneling microscopy/spectroscopy. The flatband was clearly observed near the Fermi level. We also revealed a small bandgap of ∼20 meV between the flatband and the conduction band. These results demonstrate the critical states of KMgBi that transition among various types of Dirac fermions can be tuned in one system.	Jun 2021

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