Journal of Physics: Condensed Matter最新文献

{"title":"Disordered magnetic ground state in a quasi-1-D<i>d</i>⁴columnar iridate Sr₃LiIrO₆.","authors":"Abhisek Bandyopadhyay, Debu Das, A Chakraborty, S Bhowal, Vinod Kumar, G B G Stenning, C Ritter, D T Adroja, M Moretti Sala, A Efimenko, C Meneghini, F Bert, P K Biswas, I Dasgupta, T Saha Dasgupta, A V Mahajan, Sugata Ray","doi":"10.1088/1361-648X/ad63eb","DOIUrl":"10.1088/1361-648X/ad63eb","url":null,"abstract":"<p><p>Spin-orbit coupling offers a large variety of novel and extraordinary magnetic and electronic properties in otherwise 'ordinary pool' of heavy ion oxides. Here we present a detailed study on an apparently isolated hexagonal 2<i>H</i>spin-chain<i>d</i>⁴iridate Sr₃LiIrO₆with geometric frustration. Our structural studies reveal Li-Ir chemical order with desired stoichiometry in this compound, while x-ray absorption together with x-ray photoemission spectroscopic characterizations establish pure 5+ valence of Ir. We have established a magnetic ground state with finite Ir⁵⁺magnetic moments in this compound, contrary to the anticipated nonmagneticJeff= 0 state, through combined dc susceptibility,7Li nuclear magnetic resonance (NMR), muon spin relaxation (<i>µ</i>SR) and<i>ab-initio</i>electronic structure studies. These investigations together with ac magnetic susceptibility and specific heat measurements reveal that despite having noticeable antiferromagnetic correlation among the Ir⁵⁺local moments, this system does not magnetically order down to at least 0.05 K, possibly due to geometrical exchange frustration, arising from the comparable nearest- and next-nearest-neighbor interchain Ir-O-O-Ir superexchange interaction strengths with opposite signs. However, the zero-field<i>µ</i>SR analysis shows emergence of a considerable proportion of spin-freezing on top of a spin-fluctuating dynamic magnetic background down to the lowest measured temperature of 1.7 K, possibly due to some inhomogeneity and/or the much stronger intra-column Ir-Ir magnetic exchange interaction strength relative to the inter-column Ir-Ir ones. The linear temperature dependence of the magnetic specific heat (Cm) in both zero and applied magnetic fields, plus the power-law behavior of the NMR spin-lattice relaxation rate suggest a gapless spinon density of states in this charge gapped disordered magnetic ground state of Sr₃LiIrO₆.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141626953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient determination of Born-effective charges, LO-TO splitting, and Raman tensors of solids with a real-space atom-centered deep learning approach.","authors":"Olivier Malenfant-Thuot, Kevin Ryczko, Isaac Tamblyn, Michel Côté","doi":"10.1088/1361-648X/ad64a2","DOIUrl":"10.1088/1361-648X/ad64a2","url":null,"abstract":"<p><p>We introduce a deep neural network (DNN) framework called the<b>R</b>eal-space<b>A</b>tomic<b>D</b>ecomposition<b>NET</b>work (radnet), which is capable of making accurate predictions of polarization and of electronic dielectric permittivity tensors in solids and aims to address limitations of previously available machine learning models for Raman predictions in periodic systems. This framework builds on previous, atom-centered approaches while utilizing deep convolutional neural networks. We report excellent accuracies on direct predictions for two prototypical examples: GaAs and BN. We then use automatic differentiation to efficiently calculate the Born-effective charges, longitudinal optical-transverse optical (LO-TO) splitting frequencies, and Raman tensors of these materials. We compute the Raman spectra, and find agreement with<i>ab initio</i>results. Lastly, we explore ways to generalize the predictions of polarization while taking into account periodic boundary conditions and symmetries.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141633830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure and scaling of Kitaev chain across a quantum critical point in real space.","authors":"Yan He, Chih-Chun Chien","doi":"10.1088/1361-648X/ad64a0","DOIUrl":"10.1088/1361-648X/ad64a0","url":null,"abstract":"<p><p>The spatial Kibble-Zurek mechanism is applied to the Kitaev chain with inhomogeneous pairing interactions that vanish in half of the lattice and result in a quantum critical point separating the superfluid and normal-gas phases in real space. The weakly-interacting BCS theory predicts scaling behavior of the penetration of the pair wavefunction into the normal-gas region different from conventional power-law results due to the non-analytic dependence of the BCS order parameter on the interaction. The Bogoliubov-de Gennes (BdG) equation produces numerical results confirming the scaling behavior and hints complications in the strong-interaction regime. The limiting case of the step-function quench reveals the dominance of the BCS coherence length in absence of additional length scale. Furthermore, the energy spectrum and wavefunctions from the BdG equation show abundant in-gap states from the normal-gas region in addition to the topological edge states.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141633832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscosity of Al-Ni-Co-Nd(Sm) glass-forming melts at high temperatures.","authors":"A I Rusanova, B A Rusanov, A L Beltyukov, V E Sidorov, L D Son","doi":"10.1088/1361-648X/ad649e","DOIUrl":"10.1088/1361-648X/ad649e","url":null,"abstract":"<p><p>Obtaining amorphous alloys with good mechanical and anticorrosion properties is an important problem of modern condensed matter physics. Since the preparation of amorphous alloys involves casting them from liquid state, information on the properties of the melts is needed. Viscosity is one of the most informative structure-sensitive property of melts. In this paper viscosity of some glass-forming Al-Ni-Co-Nd(Sm) melts with different ratio of transition metals was studied using damped oscillation method in a wide temperature range up to 1550 K. Activation energies of the viscous flow were calculated from the experimental data. The hysteresis of viscosity temperature dependences during heating and subsequent cooling was found. It can be associated with a melt transition to a more homogeneous state. The repeated heating and cooling of the melts without crystallization lead to Arrhenius type of viscosity temperature dependences.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141633833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Particle-assisted formation of oil-in-liquid metal emulsions.","authors":"Shreyas Kanetkar, Najam Ul H Shah, Febby Krisnadi, Aastha Uppal, Rohit M Gandhi, Michael D Dickey, Robert Y Wang, Konrad Rykaczewski","doi":"10.1088/1361-648X/ad6521","DOIUrl":"10.1088/1361-648X/ad6521","url":null,"abstract":"<p><p>Gallium-based liquid metals (LMs) have surface tension an order of magnitude higher than water and break up into micro-droplets when mixed with other liquids. In contrast, silicone oil readily mixes into LM foams to create oil-in-LM emulsions with oil inclusions. Previously, the LM was foamed through rapid mixing in air for an extended duration (over 2 h). This process first results in the internalization of oxide flakes that form at the air-liquid interface. Once a critical fraction of these randomly shaped solid flakes is reached, air bubbles internalize into the LM to create foams that can internalize secondary liquids. Here, we introduce an alternative oil-in-LM emulsion fabrication method that relies on the prior addition of SiO₂micro-particles into the LM before mixing it with the silicone oil. This particle-assisted emulsion formation process provides a higher control over the composition of the LM-particle mixture before oil addition, which we employ to systematically study the impact of particle characteristics and content on the emulsions' composition and properties. We demonstrate that the solid particle size (0.8<i>μ</i>m to 5<i>μ</i>m) and volume fraction (1%-10%) have a negligible impact on the internalization of the oil inclusions. The inclusions are mostly spherical with diameters of 20-100<i>μ</i>m diameter and are internalized by forming new, rather than filling old, geometrical features. We also study the impact of the particle characteristics on the two key properties related to the functional application of the LM emulsions in the thermal management of microelectronics. In particular, we measure the impact of particles and silicone oil on the emulsion's thermal conductivity and its ability to prevent deleterious gallium-induced corrosion and embrittlement of contacting metal substrates.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141723791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interplay of size, deformability, and device layout on cell transport in microfluidics.","authors":"Michael C Hood, Karl Gardner, Wei Li, Jifu Tan","doi":"10.1088/1361-648X/ad5ff3","DOIUrl":"10.1088/1361-648X/ad5ff3","url":null,"abstract":"<p><p>Microfluidics have been widely used for cell sorting and capture. In this work, numerical simulations of cell transport in microfluidic devices were studied considering cell sizes, deformability, and five different device designs. Among these five designs, deterministic lateral displacement device (DLD) and hyperuniform device (HU) performed better in promoting cell-micropost collision due to the continuously shifted micropost positions as compared with regular grid, staggered, and hexagonal layout designs. However, the grid and the hexagonal layouts showed best in differentiating cells by their size dependent velocity due to the size exclusion effect for cell transport in clear and straight paths in the flow direction. A systematic study of the velocity differentiation under different dimensionless groups was performed showing that the velocity difference is dominated by the micropost separation distance perpendicular to the direction of flow. Microfluidic experiments also confirmed the velocity differentiation results. The study can provide guiding principles for microfluidic design.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141555073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis of absorption resonances between carbynes and cyclo[n]carbons.","authors":"Renebeth B Payod, Aliaxandr L Pushkarchuk, Dominik L Michels, Dmitry A Lyakhov, Vasil A Saroka","doi":"10.1088/1361-648X/ad61ab","DOIUrl":"10.1088/1361-648X/ad61ab","url":null,"abstract":"<p><p>Two approaches are presented here to analyze the absorption resonances between carbynes and cyclo[n]carbons, namely the analytical tight-binding model to calculate the optical selection rules of cumulenic atomic rings and chains and the<i>ab initio</i>time-dependent density functional theory for the optical investigation of polyynic carbon ring and chains. The optical absorption spectra of the carbon ring match that of the finite chain when their eigen energies align following theNring=2Nchain+2rule, which states that the number of atoms in an atomic ringNringis twice the number of atoms on a finite chainNchainwith two additional atoms. Two representative atomic chains are chosen for our numerical calculations, specifically carbynes withN=7and8carbon atoms as optical resonance spectra match to a recently synthesized carbon ring called cyclo[18]carbon. Despite the mismatch in resonance peaks, molecular orbital transitions of both carbynes<i>N</i> = 7 and 8 and cyclo[18]carbon reveal a wave function symmetry change from inversion to reflection and vice versa for allowed molecular orbital transitions, which results in electron density redistribution along the polyynic carbyne axis or the cyclo[18]carbon circumference. Our investigation of the correlation of optical absorption peaks between carbynes and cyclo[n]carbons is a step towards enhancing the reliability of allotrope identification in advanced molecular device spectroscopy. Moreover, this work could facilitate the non-invasive, rapid and crucial assessment of these sensitive 1D allotropes by providing accurate descriptions of their electronic and optical properties, particularly in controlled synthesis environments.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141579972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles calculation of Hubbard<i>U</i>for Terbium metal under high pressure.","authors":"Logan A Burnett, Matthew P Clay, Yogesh K Vohra, Cheng-Chien Chen","doi":"10.1088/1361-648X/ad6387","DOIUrl":"10.1088/1361-648X/ad6387","url":null,"abstract":"<p><p>Using density functional theory (DFT) and linear response approaches, we compute the on-site Hubbard interaction<i>U</i>of elemental Terbium (Tb) metal in the pressure range ∼ 0-65 GPa. The resulting first-principles<i>U</i>values with experimental crystal structures enable us to examine the magnetic properties of Tb using a DFT+U method. The lowest-energy magnetic states in our calculations for different high-pressure Tb phases-including hcp,<i>α</i>-Sm, and dhcp-are found to be compatible with the corresponding magnetic ordering vectors reported in experiments. The result shows that the inclusion of Hubbard<i>U</i>substantially improves the accuracy and efficiency in modeling correlated rare-earth materials. Our study also provides the necessary<i>U</i>information for other quantum many-body techniques to study Tb under extreme pressure conditions.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141620227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoupling the rheological responses of a soft solid emulsion with liquid inclusions.","authors":"E Gilbert, A Salonen, C Poulard","doi":"10.1088/1361-648X/ad61ad","DOIUrl":"10.1088/1361-648X/ad61ad","url":null,"abstract":"<p><p>Soft solid emulsions are liquid droplets encapsulated in a soft solid material. Typical of dispersed systems, they can combine properties from both the liquid inclusions and the soft solids. The relative importance of the two phases in the rheological response is captured through the elastocapillary number, which compares capillary forces in the liquid inclusions to the matrix rigidity. We work with solid emulsions formed of poly(ethylene glycol) droplets in a poly(dimethylsiloxane) (PDMS) continuous phase. We create three families of emulsions with varying elastocapillary numbers, and range of inclusion volume fractions from 0 to 0.5. Through oscillatory rheology we probe both the elastic response and the dissipative effects of liquid droplets. In the case of a dominant response from the continuous phase or the drops, the results can be described with Palierne's model. However, for the intermediate elastocapillary series we show that the evolution of the storage and loss moduli decouple with dispersed phase volume fraction. We attribute the increase of loss factor with volume fraction to the high polydispersity in droplet size. We can further modulate the response of the materials by cooling to freeze the droplets. This approach allows us to compare these soft solid emulsions with theories related to solid dispersions.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141579973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles study of phase-dependent carrier transport mechanism for MASnI₃Sn-based halide perovskite.","authors":"Mingming Li, Jiajia Fei, Xiaojiao Zhang, Jialin Li, Chuanjia Tong, Mengqiu Long","doi":"10.1088/1361-648X/ad604e","DOIUrl":"10.1088/1361-648X/ad604e","url":null,"abstract":"<p><p>Organic-inorganic hybrid perovskites have attracted tremendous attentions owing to their excellent properties as next-generation photovoltaic devices. With soft covalent framework, organic-inorganic hybrid perovskites exhibit different phases at different temperatures. The band-edge features of perovskites are mainly contributed by inorganic framework, which means the structural differences between these phases would lead to complex carrier transport. We investigated the carrier transport of Sn-based organic-inorganic hybrid perovskite CH₃NH₃SnI₃(MASnI₃), considering acoustic deformation potential scattering, ionized impurity scattering, and polar optical phonon scattering. It is found that the electron mobility of each phase of MASnI₃is strongly correlated with the Sn-I-Sn bond angle and there is in-plane/out-of-plane anisotropy. The projected crystal orbital Hamilton population analysis suggested that the tilt and rotation of the [SnI₆]^4-octahedron influence the Sn(<i>p</i>)-I(<i>p</i>) orbital electron coupling and the electron transport, leading to different band-edge features in multiple phases. The carrier mobility with respect to temperature was further calculated for each phase of MASnI₃in respective temperature intervals, showing lower carrier mobility in high temperature. Comparing the contribution of different scattering mechanisms, it was found that the dominant scattering mechanism is polar optical phonon scattering, while multiple scattering mechanisms compete in individual cases.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141558984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}