Physical Review Materials最新文献

{"title":"First-principles study of the order-disorder transition in the AlCrTiV high entropy alloy","authors":"Michael Widom","doi":"10.1103/physrevmaterials.8.093603","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.093603","url":null,"abstract":"The AlCrTiV high entropy alloy undergoes an order-disorder transition from body-centered cubic (Strukturbericht A2) at high temperatures to the CsCl structure (B2) at intermediate temperatures. We model this transition using first principles Monte Carlo/molecular dynamics simulations. Simulation results yield the temperature-dependent energy, entropy, heat capacity, occupancy fluctuations, and diffraction patterns. The contribution of chemical disorder to the entropy is calculated on the basis of point and pair cluster frequencies. The simulated structures exhibit compensated ferrimagnetism, and the Fermi level lies in a pseudogap. Sensitivity of structure and magnetism to the exchange-correlation functional is discussed, and neutron diffraction experiments are proposed to help resolve the true chemical order.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"10 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic properties of the quasi-XY Shastry-Sutherland magnet Er2Be2SiO7","authors":"A. Brassington, Q. Ma, G. Sala, A. I. Kolesnikov, K. M. Taddei, Y. Wu, E. S. Choi, H. Wang, W. Xie, J. Ma, H. D. Zhou, A. A. Aczel","doi":"10.1103/physrevmaterials.8.094001","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.094001","url":null,"abstract":"Polycrystalline and single-crystal samples of the insulating Shastry-Sutherland compound <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Er</mi><mn>2</mn></msub><msub><mi>Be</mi><mn>2</mn></msub><msub><mi>SiO</mi><mn>7</mn></msub></mrow></math> were synthesized via a solid-state reaction and the floating zone method, respectively. The crystal structure, Er single-ion anisotropy, zero-field magnetic ground state, and magnetic phase diagrams along high-symmetry crystallographic directions were investigated with bulk measurement techniques, x-ray and neutron diffraction, and neutron spectroscopy. We establish that <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Er</mi><mn>2</mn></msub><msub><mi>Be</mi><mn>2</mn></msub><msub><mi>SiO</mi><mn>7</mn></msub></mrow></math> crystallizes in a tetragonal space group with planes of orthogonal Er dimers and a strong preference for the Er moments to lie in the local plane perpendicular to each dimer bond. We also find that this system has a noncollinear ordered ground state in zero field with a transition temperature of 0.841 K consisting of antiferromagnetic dimers and in-plane moments. Finally, we mapped out the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>H</mi><mtext>−</mtext><mi>T</mi></mrow></math> phase diagrams for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Er</mi><mn>2</mn></msub><msub><mi>Be</mi><mn>2</mn></msub><msub><mi>SiO</mi><mn>7</mn></msub></mrow></math> along the directions <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>H</mi><mo>∥</mo></mrow></math> [001], [100], and [110]. While an increasing in-plane field simply induces a phase transition to a field-polarized phase, we identify three metamagnetic transitions in the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>H</mi><mo>∥</mo></mrow></math> [001] case. Single-crystal neutron diffraction results reveal that the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>H</mi><mo>∥</mo></mrow></math> [001] phase diagram can be explained predominantly by the expected field-induced behavior of classical, anisotropic moments, although the microscopic origin of one phase requires further investigation.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"8 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Symmetry-driven large tunneling magnetoresistance in SrRuO3 magnetic tunnel junctions with perpendicular magnetic anisotropy","authors":"Anouk S. Goossens, Kartik Samanta, Azminul Jaman, Wissem Boubaker, Job J. L. van Rijn, Evgeny Y. Tsymbal, Tamalika Banerjee","doi":"10.1103/physrevmaterials.8.l091401","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.l091401","url":null,"abstract":"Magnetic tunnel junctions (MTJs) that are comprised of epitaxially grown complex oxides offer a versatile platform to control the symmetry of tunneling states and tailor magnetic anisotropy useful for practical applications. This work employs thin films of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>SrTiO</mi><mn>3</mn></msub></math> as an insulating barrier deposited between two ferromagnetic <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>SrRuO</mi><mn>3</mn></msub></math> electrodes to form fully epitaxial MTJs and demonstrate these functionalities. Transport measurements demonstrate large tunneling magnetoresistance (TMR), significantly exceeding previously found values of TMR in MTJs based on <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>SrRuO</mi><mn>3</mn></msub></math> electrodes. These results are explained by perpendicular magnetic anisotropy of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>SrRuO</mi><mn>3</mn></msub></math> and matching (mismatching) between symmetry and spin across the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>SrTiO</mi><mn>3</mn></msub><mo>/</mo><msub><mi>SrRuO</mi><mn>3</mn></msub></mrow></math> (001) interface for the parallel (antiparallel) MTJ magnetization state, supported by density functional (DFT) calculations. The angular variation of TMR indicates that the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>SrRuO</mi><mn>3</mn></msub></math> electrodes contain multiple magnetic domains, allowing the devices to exhibit at least three stable resistance states.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"110 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recurrence of superconductivity in thickness-gradient La1.81Ce0.19CuO4−δ film","authors":"Sijia Tu, Jinsong Zhang, Zefeng Lin, Beiyi Zhu, Qihong Chen, Jie Yuan, Kui Jin","doi":"10.1103/physrevmaterials.8.094801","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.094801","url":null,"abstract":"We report a systematic study of the thickness effect on the superconductivity of overdoped <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">L</mi><msub><mi mathvariant=\"normal\">a</mi><mrow><mn>2</mn><mo>−</mo><mi>x</mi></mrow></msub><mi mathvariant=\"normal\">C</mi><msub><mi mathvariant=\"normal\">e</mi><mi>x</mi></msub><mi>Cu</mi><msub><mi mathvariant=\"normal\">O</mi><mrow><mn>4</mn><mo>−</mo><mi>δ</mi></mrow></msub></mrow></math> films. As the film thickness decreases, a recurrence of superconductivity is observed in the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>0.19</mn></mrow></math> film, while this doping level is commonly expected to show Fermi liquid behavior. The superconducting critical temperatures exhibit a domelike shape with varying thickness. The magnetic susceptibility measurements suggest that the presence of superconductivity in thin films should be filamentary. The combined effect of stress and oxygen in the thickness-gradient films is proposed to comprehend the experimental observations. Our findings provide new perspectives on superconductivity in other systems, such as the hotly debated nickelate superconductors.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"45 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Absence of itinerant ferromagnetism in a cobalt-based oxypnictide","authors":"Hua-Xun Li, Hao Jiang, Yi-Qiang Lin, Jia-Xin Li, Shi-Jie Song, Qin-Qing Zhu, Zhi Ren, Guang-Han Cao","doi":"10.1103/physrevmaterials.8.094405","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.094405","url":null,"abstract":"We report a layered transition-metal-ordered oxypnictide <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Sr</mi><mn>2</mn></msub><msub><mi>CrCoAsO</mi><mn>3</mn></msub></mrow></math>. The new material was synthesized by solid-state reactions under vacuum. It has an intergrowth structure with a perovskite-like <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Sr</mi><mn>3</mn></msub><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>6</mn></msub></mrow></math> unit and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>ThCr</mi><mn>2</mn></msub><msub><mi>Si</mi><mn>2</mn></msub></mrow></math>-type <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>SrCo</mi><mn>2</mn></msub><msub><mi>As</mi><mn>2</mn></msub></mrow></math> block stacking coherently along the crystallographic <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>c</mi></math> axis. The measurements of electrical resistivity, magnetic susceptibility, and specific heat indicate metallic conductivity from the CoAs layers and short-range antiferromagnetic ordering in the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>CrO</mi><mn>2</mn></msub></math> planes. No itinerant-electron ferromagnetism expected in CoAs layers is observed. This result, combined with the first-principles calculations and the previous reports of other CoAs-layer-based materials, suggests that the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Co</mi><mo>−</mo><mi>Co</mi></mrow></math> bond length plays a crucial role in the emergence of itinerant ferromagnetism.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tuning magnetic correlations in s=1/2 spin ladder Ba2CuTe1−xWxO6 through site-selective cation substitution","authors":"Muskan Sande, Joydev Khatua, Youngsu Choi, Kwang-Yong Choi","doi":"10.1103/physrevmaterials.8.094404","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.094404","url":null,"abstract":"The site-selective substitution of diamagnetic <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mrow><mi>d</mi></mrow><mn>10</mn></msup><mo>/</mo><msup><mrow><mi>d</mi></mrow><mn>0</mn></msup></mrow></math> cations offers an efficient way to fine-tune magnetic characteristics by controlling orbital hybridization and superexchange pathways. Herein, we explore the tunability of magnetic properties in coupled spin-ladder compounds <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">B</mi><msub><mi mathvariant=\"normal\">a</mi><mn>2</mn></msub><mi>CuT</mi><msub><mi mathvariant=\"normal\">e</mi><mrow><mn>1</mn><mrow><mtext>−</mtext><mi>x</mi></mrow></mrow></msub><msub><mi mathvariant=\"normal\">W</mi><mi>x</mi></msub><msub><mi mathvariant=\"normal\">O</mi><mn>6</mn></msub></mrow></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>0.0</mn><mo>−</mo><mn>0.30</mn></mrow></math>). The pristine compound exhibits spin-singlet correlations at elevated temperatures, as evidenced by a magnetic susceptibility peak at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>T</mi><mi>max</mi></msub><mo>∼</mo><mn>70</mn></mrow></math> K, Schottky-like specific heat, unconventional magnetic Raman scattering, and a quasilinear decrease in the electron spin resonance linewidth. Notably, the substitution of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi mathvariant=\"normal\">W</mi></mrow><mrow><mn>6</mn><mo>+</mo></mrow></msup></math> for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">T</mi><msup><mrow><mi mathvariant=\"normal\">e</mi></mrow><mrow><mn>6</mn><mo>+</mo></mrow></msup></mrow></math> brings about several marked changes: an increase in the Curie-Weiss temperature, a suppression in the Néel ordering temperature, enhanced magnetic susceptibility at low temperatures, and a weakening of spin-ladder correlations. These modifications collectively suggest that the newly activated exchange interactions through <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi mathvariant=\"normal\">W</mi></mrow><mrow><mn>6</mn><mo>+</mo></mrow></msup></math> substitution primarily alter intraladder spin topology while amplifying quantum critical fluctuations. This finding highlights the potential for controlling magnetic correlations in spin-ladder compounds through targeted chemical substitution.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"57 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uncovering the presence or absence of photoluminescence from iron ions in crystals","authors":"Qiaoling Chen, Qianshan Quan, Chang-Kui Duan","doi":"10.1103/physrevmaterials.8.095201","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.095201","url":null,"abstract":"The poor understanding of the optical transitions and luminescent mechanisms critically hindered the development of near-infrared (NIR) <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi>Fe</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math>-activated phosphors, and efficient luminescence from Fe(Oh) has rarely been reported. In our study, we delve into these challenges and realize their correlation with the quenching mechanism of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi>Fe</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math> luminescence. First-principles calculations are utilized to analyze energy levels and electron-phonon coupling parameters, further elucidating potential deactivation pathways and factors influencing the occurrence of photoluminescence. A heuristic rule based on ligand-field strength, determined by the absorption wavelength of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi>Cr</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math> occupying the same octahedral site in oxides, is proposed to facilitate the prediction of both the potential and wavelength of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi>Fe</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math> emission. Our study offers consistent and reliable interpretations for the difficulties and challenges of iron-doped crystals, and provides valuable insights on the design and optimization of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mi>Fe</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math>-based phosphors.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"30 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural mechanism of the magnetic phase transitions in FeTiO3","authors":"A. Zafar, A. M. Milinda Abeykoon, V. Petkov","doi":"10.1103/physrevmaterials.8.093602","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.093602","url":null,"abstract":"The structural mechanism of the magnetic phase transitions in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>FeTiO</mi><mn>3</mn></msub></math> ilmenite, including the paramagnetic (PM) to antiferromagnetic (AFM) transition induced by reducing temperature in zero magnetic field and the AFM to ferromagnetic (FM) transition induced by applying strong magnetic field at a fixed temperature below the Néel temperature, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi mathvariant=\"normal\">N</mi></msub></math>, are studied by total synchrotron x-ray scattering. It is found that in both cases the concerted effect of Coulomb repulsion, spin-orbit coupling, and exchange interactions is what determines the response of the crystal lattice to variations in external perturbations such as temperature and magnetic field. In particular, due to strong spin-orbit coupling and Coulomb repulsion, Fe and Ti atoms move in sync along the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>c</mi></math> axis of the crystal lattice such that their separation changes by less than 1%. At the same time, due to strong intralayer ferromagnetic interactions, the Fe-O-Fe bond angle becomes closer to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>90</mn><mo>∘</mo></msup></math>. Notably, the direction of the motion occuring during the temperature-induced PM to AFM transition is opposite to that occuring during the magnetic field-induced AFM to FM transition. Altogether, the seemingly simple <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>FeTiO</mi><mn>3</mn></msub></math> ilmenite behaves like a complex physical system where charge, spin, orbital, and lattice degrees of freedom are strongly coupled. Our findings are likely to be relevant to other members of the ilmenite family and spin-orbit coupled magnetic insulators in general.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"2 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase-separated charge order and twinning across length scales in CsV3Sb5","authors":"Jayden Plumb, Andrea Capa Salinas, Krishnanand Mallayya, Elliot Kisiel, Fellipe B. Carneiro, Reina Gomez, Ganesh Pokharel, Eun-Ah Kim, Suchismita Sarker, Zahirul Islam, Sam Daly, Stephen D. Wilson","doi":"10.1103/physrevmaterials.8.093601","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.093601","url":null,"abstract":"We present x-ray scattering studies resolving structural twinning and phase separation in the charge density wave (CDW) state of the kagome superconductor <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>CsV</mi><mn>3</mn></msub><msub><mi>Sb</mi><mn>5</mn></msub></mrow></math>. The three-dimensional CDW state in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>CsV</mi><mn>3</mn></msub><msub><mi>Sb</mi><mn>5</mn></msub></mrow></math> is reported to form a complex superposition of Star of David (SoD) or Tri-Hexagonal (TrH) patterns of distortion within its kagome planes, but the out-of-plane stacking is marked by metastability. To resolve the impact of this metastability, we present reciprocal space mapping and real-space images of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>CsV</mi><mn>3</mn></msub><msub><mi>Sb</mi><mn>5</mn></msub></mrow></math> collected across multiple length scales using temperature-dependent high-dynamic range mapping (HDRM) and dark-field x-ray microscopy (DFXM). The experimental data provide evidence for a rich microstructure that forms in the CDW state. Data evidence metastability in the formation of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2</mn><mo>×</mo><mn>2</mn><mo>×</mo><mn>4</mn></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2</mn><mo>×</mo><mn>2</mn><mo>×</mo><mn>2</mn></mrow></math> CDW supercells dependent on thermal history and mechanical deformation. We further directly resolve the real space phase segregation of both supercells, as well as a real-space, structural twinning driven by the broken rotational symmetry of the CDW state. Our combined results provide insights into the role of microstructure and twinning in experiments probing the electronic properties of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>CsV</mi><mn>3</mn></msub><msub><mi>Sb</mi><mn>5</mn></msub></mrow></math> where rotational symmetry is broken by the three-dimensional charge density wave order but locally preserved for any single kagome layer.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"28 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lead-free room-temperature ferroelectric thermal conductivity switch using anisotropies in thermal conductivities","authors":"Lucile Féger, Carlos Escorihuela-Sayalero, Jean-Michel Rampnoux, Kyriaki Kontou, Micka Bah, Jorge Íñiguez-González, Claudio Cazorla, Isabelle Monot-Laffez, Sarah Douri, Stéphane Grauby, Riccardo Rurali, Stefan Dilhaire, Séverine Gomès, Guillaume F. Nataf","doi":"10.1103/physrevmaterials.8.094403","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.094403","url":null,"abstract":"Materials with on-demand control of thermal conductivity are the prerequisites to build thermal conductivity switches, where the thermal conductivity can be turned <span>on</span> and <span>off</span>. However, the ideal switch, while required to develop novel approaches to solid-state refrigeration, energy harvesting, and even phononic circuits, is still missing. It should consist of an active material only, be environment friendly, and operate near room temperature with a reversible, fast, and large switching ratio. Here, we first predict by <i>ab initio</i> electronic structure calculations that ferroelectric domains in barium titanate exhibit anisotropic thermal conductivities. We confirm this prediction by combining frequency-domain thermoreflectance and scanning thermal microscopy measurements on a single crystal of barium titanate. We then use this gained knowledge to propose a lead-free thermal conductivity switch without inactive material, operating reversibly with an electric field. At room temperature, we find a switching ratio of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1.6</mn><mo>±</mo><mn>0.3</mn></mrow></math>, exceeding the performances of state-of-the-art materials suggested for thermal conductivity switches.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":"12 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}