Magnetism in artificial Ruddlesden-Popper iridates leveraged by structural distortions
D. Meyers, Yue Cao, G. Fabbris, Neil J. Robinson, Lin Hao, C. Frederick, N. Traynor, J. Yang, Jiaqi Lin, M. H. Upton, D. Casa, Jong-Woo Kim, T. Gog, E. Karapetr… 展开作者
D. Meyers, Yue Cao, G. Fabbris, Neil J. Robinson, Lin Hao, C. Frederick, N. Traynor, J. Yang, Jiaqi Lin, M. H. Upton, D. Casa, Jong-Woo Kim, T. Gog, E. Karapetrova, Yongseong Choi, D. Haskel, P. J. Ryan, Lukas Horak, X. Liu, Jian Liu, M. P. M. Dean
We report on the tuning of magnetic interactions in superlattices composed of single and bilayer SrIrO$_3$ inter-spaced with SrTiO$_3$. Magnetic scattering shows predominately $c$-axis antiferromagnetic orientation of the magnetic moments for the bilayer justifying these systems as viable artificial analogues of the bulk Ruddlesden-Popper series iridates. Magnon gaps are observed in both superlattices, with the magnitude of the gap in the bilayer being reduced to nearly half that in its bulk structural analogue, Sr$_3$Ir$_2$O$_7$. We assign this to modifications in the anisotropic exchange driven by bending of the $c$-axis Ir-O-Ir bond and subsequent local environment changes, as detected by x-ray diffraction and modeled using spin wave theory. These findings explain how even subtle structural modulations driven by heterostructuring in iridates are leveraged by spin orbit coupling to drive large changes in the magnetic interactions.
Ruddlesden-Popper and reduced Ruddlesden-Popper nickelates are intriguing candidates for mimicking the properties of high-temperature superconducting cuprates. The degree of similarity between these nickelates and cuprates has been the subject of considerable debate. Resonant inelastic x-ray scattering (RIXS) has played an important role in exploring their electronic and magnetic excitations, but these efforts have been stymied by inconsistencies between different samples and the lack of publicly available data for detailed comparison. To address this issue, we present open RIXS data on La4Ni3…
The goal of this work is studying the evolution of thermoelectric transport across the members of the Ruddlesden-Popper series iridates Srn+1IrnO3n+1, where a metal-insulator transition driven by bandwidth change occurs, from the strongly insulating Sr2IrO4 to the metallic non Fermi liquid behavior of SrIrO3. Sr2IrO4 (n=1), Sr3Ir2O7 (n=2) and SrIrO3 (n=inf.) polycrystals are synthesized at high pressure and characterized by structural, magnetic, electric and thermoelectric transport analyses. We find a complex thermoelectric phenomenology in the three compounds. Thermal diffusion of charge car…
We analyze the electronic structure of the recently synthesized higher-order nickelate Ruddlesden-Popper phases La$_{n+1}$Ni$_n$O$_{3n+1}$ ($n=4-6$) using first-principles calculations. For all materials, our results show large holelike Fermi surfaces with $d_{x^2-y^2}$ character that closely resemble those of optimally hole-doped cuprates. For higher values of $n$, extra non-cuprate-like bands of $d_{z^2}$ orbital character appear. These aspects highlight that this Ruddlesden-Popper series can provide a means to modify the electronic ground states of nickelates by tuning their dimensionality.…
We report on the selective fabrication of high-quality Sr$_2$IrO$_4$ and SrIrO$_3$ epitaxial thin films from a single polycrystalline Sr$_2$IrO$_4$ target by pulsed laser deposition. Using a combination of X-ray diffraction and photoemission spectroscopy characterizations, we discover that within a relatively narrow range of substrate temperature, the oxygen partial pressure plays a critical role in the cation stoichiometric ratio of the films, and triggers the stabilization of different Ruddlesden-Popper (RP) phases. Resonant X-ray absorption spectroscopy measurements taken at the Ir $L$-edge…
We study the optical properties of the Ruddlesden-Popper series of iridates Sr$_{n+1}$Ir$_n$O$_{3n+1}$ ($n$=1, 2 and $\infty$) by solving the Bethe-Salpeter equation (BSE), where the quasiparticle (QP) energies and screened interactions $W$ are obtained by the $GW$ approximation including spin-orbit coupling. The computed optical conductivity spectra show strong excitonic effects and reproduce very well the experimentally observed double-peak structure, in particular for the spin-orbital Mott insulators Sr$_2$IrO$_4$ and Sr$_3$Ir$_2$O$_7$. However, $GW$ does not account well for the correlated…
A series of Ruddlesden-Popper nickelates, Nd$_{n+1}$Ni$_{n}$O$_{3n+1}$ (${n}$ = 1-5), have been stabilized in thin film form using reactive molecular-beam epitaxy. High crystalline quality has been verified by X-ray diffraction and scanning transmission electron microscopy. X-ray photoelectron spectroscopy indicates the ${n}$-dependent valence states of nickel in these compounds. Metal-insulator transitions show clear ${n}$ dependence for intermediate members (${n}$ = 3-5), and the low-temperature resistivities of which show logarithmic dependence, resembling the Kondo-scattering as observed i…
We study the correlated electronic structure of single-layer iridates based on structurally-undistorted Ba$_2$IrO$_4$. Starting from the first-principles band structure, the interplay between local Coulomb interactions and spin-orbit coupling is investigated by means of rotational-invariant slave-boson mean-field theory. The evolution from a three-band description towards an anisotropic one-band ($J=1/2$) picture is traced. Single-site and cluster self-energies are used to shed light on competing Slater- and Mott-dominated correlation regimes. We reveal a clear asymmetry between electron and h…
With the use of lattice dynamics calculation within hybrid HSE06 framework we were able to understand vibrational spectra of MAgF3 M = K, Rb, Cs compounds. Comparative theoretical study uncovered lack of monotonicity in calculated optical phonons associated with Ag F stretching modes which can be explained through an interplay of Lewis acidity of MI cation and its size. We confirm the tetragonal unit cells of MAgF3 M=Rb, Cs at room temperature. We also theoretically predict an orthorhombic RbAgF3 polymorph as a ground state at low temperature. However, we were not able to detect it by the mean…
The rare-earth nickelates possess a diverse set of collective phenomena including metal-to-insulator transitions, magnetic phase transitions, and, upon chemical reduction, superconductivity. Here, we demonstrate epitaxial stabilization of layered nickelates in the Ruddlesden-Popper form, Nd$_{n+1}$Ni$_n$O$_{3n+1}$, using molecular beam epitaxy. By optimizing the stoichiometry of the parent perovskite NdNiO$_3$, we can reproducibly synthesize the $n = 1 - 5$ member compounds. X-ray absorption spectroscopy at the O $K$ and Ni $L$ edges indicate systematic changes in both the nickel-oxygen hybrid…
Layer Architecture Shapes Electronic, Magnetic, and Lattice Interactions in Ruddlesden-Popper Nickelates
Brookhaven National Laboratory（布鲁克海文国家实验室）；Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory（斯坦福物质与能源科学研究所，SLAC国家加速器实验室）；The University of Tennessee, Knoxville（田纳西大学诺克斯维尔分校）；Harvard University（哈佛大学）；Argonne National Laboratory（阿贡国家实验室）；Oak Ridge National Laboratory（橡树岭国家实验室）；National Synchrotron Light Source II, Brookhaven National Laboratory（国家同步光源二期，布鲁克海文国家实验室）
In this study, we systematically investigate 3D momentum($\hbar k$)-resolved electronic structures of Ruddlesden-Popper-type iridium oxides Sr$_{n+1}$Ir$_n$O$_{3n+1}$ using soft-x-ray (SX) angle-resolved photoemission spectroscopy (ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO$_2$-plane structure. This transition occurs when the spin-orbit-coupled $j_{\rm eff}$=1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. In addition, an emerging band along the $Γ$(0,0,0)-R…
The 2D layered Ruddlesden-Popper crystal structure can host a broad range of functionally important behaviors. Here we establish extraordinary configurational disorder in a two dimensional layered Ruddlesden-Popper (RP) structure using entropy stabilization assisted synthesis. A protype A2CuO4 RP cuprate oxide with five components (La, Pr, Nd, Sm, Eu) on the A-site sublattice is designed and fabricated into epitaxial single crystal films using pulsed laser deposition. By comparing (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 crystals grown under identical conditions but different substrates, it is found t…
In this work, the high entropy oxide A2CuO4 Ruddlesden-Popper (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 is explored by charge doping with Ce+4 and Sr+2 at concentrations known to induce superconductivity in the simple parent compounds, Nd2CuO4 and La2CuO4. Electron doped (La0.185Pr0.185Nd0.185Sm0.185Eu0.185Ce0.075)2CuO4 and hole doped (La0.18Pr0.18Nd0.18Sm0.18Eu0.18Sr0.1)2CuO4 are synthesized and shown to be single crystal, epitaxially strained, and highly uniform. Transport measurements demonstrate that all as-grown films are insulating regardless of doping. Annealing studies show that resistivity can…
Enhancement of giant magnetoresistance effect in the Ruddlesden-Popper phase Sr3Fe2-xCoxO7-d: Predominant role of oxygen nonstoichiometry and magnetic phase separation
Interlayer electronic coherence links magnetism and superconductivity in Ruddlesden-Popper nickelates
State Key Laboratory of Surface Physics and Department of Physics, Fudan University（复旦大学表面物理国家重点实验室和物理系）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）；Institute of Nanoelectronics and Quantum Computing, Fudan University（复旦大学纳米电子与量子计算研究所）
Comparative Raman study of Ruddlesden-Popper nickelates and the monolayer-trilayer polymorph
Max-Planck-Institute for Solid State Research（马克斯·普朗克固体的研究所）；Hefei National Laboratory（合肥国家实验室）；University of Science and Technology Beijing（北京科技大学）；University of Stuttgart（斯图加特大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
Contrasting Spin Excitations in Octahedral and Square-Planar n=8 Ruddlesden-Popper Nickelates
Yale University（耶鲁大学）；Flatiron Institute（平顿研究所）；Harvard University（哈佛大学）；Donostia International Physics Center (DIPC)（多诺斯蒂亚国际物理中心）；University of California San Diego（加利福尼亚大学圣迭戈分校）；European Synchrotron Radiation Facility（欧洲同步辐射装置）
Itinerant Nature of Spin-Density-Wave Order in Ruddlesden-Popper Nickelates
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
The local epitaxial growth of pulsed laser deposited Ca$_2$MnO$_4$ films on polycrystalline spark plasma sintered Sr$_2$TiO$_4$ substrates was investigated to determine phase formation and preferred epitaxial orientation relationships ($ORs$) for isostructural Ruddlesden-Popper (RP) heteroepitaxy, further developing the high-throughput synthetic approach called Combinatorial Substrate Epitaxy (CSE). Both grazing incidence X-ray diffraction and electron backscatter diffraction (EBSD) patterns of the film and substrate were indexable as single-phase RP-structured compounds. The optimal growth te…
Three-Dimensional Electronic Structures in Superconducting Ruddlesden-Popper Bilayer Nickelate Films
Southern University of Science and Technology（南方科技大学）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；University of Science and Technology of China（中国科学技术大学）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）
We perform density functional theory plus dynamical mean field theory calculations to investi- gate internal charge transfer in an artificial superlattice composed of alternating layers of vanadate and manganite perovskite and Ruddlesden-Popper structure materials. We show that the elec- tronegativity difference between vanadium and manganese causes moderate charge transfer from VO2 to MnO2 layers in both perovskite and Ruddlesden-Popper based superlattices, leading to hole doping of the VO2 layer and electron doping of the MnO2 layer. Comparison of the perovskite and Ruddlesden-Popper based h…
Electronic structures across superconductor-insulator transition in Ruddlesden-Popper bilayer nickelate films
University of Science and Technology of China（中国科学技术大学）；Hefei National Laboratory, University of Science and Technology of China（合肥国家实验室，中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（微观尺度物理科学合肥国家研究中心，中国科学技术大学）；Southern University of Science and Technology（南方科技大学）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；Nanjing University（南京大学）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）
Dissecting superconductivity in the Ruddlesden-Popper nickelates: The role of electron correlation and interlayer magnetic exchange
Diamond Light Source（钻石光源）；National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China（中国科学技术大学核科学与技术学院/国家同步辐射实验室）；Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-Sen University（中山大学物理学院/广东省铁电与磁器件重点实验室）；Department of Physics, University of Oxford（牛津大学物理系）；National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University（南京大学固体微结构物理国家重点实验室/物理学院）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）
Thermodynamic phase transition, pairing symmetry and Fermi surface topology in Ruddlesden-Popper nickelate films
University of Science and Technology of China（中国科学技术大学）；Hefei National Laboratory, University of Science and Technology of China（合肥国家实验室，中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（中国科学院微观结构国家重点实验室，中国科学技术大学）
General trends of electronic structures, superconducting pairing, and magnetic correlations in the Ruddlesden-Popper nickelate $m$-layered superconductors La$_{m+1}$Ni$_{m}$O$_{3m+1}$
The quasi-two-dimensional nickelate La4Ni3O8 (La-438) is an anion deficient n=3 Ruddlesden-Popper (R-P) phase that consists of trilayer networks of square planar Ni ions, formally assigned as Ni1+ and Ni2+ in a 2:1 ratio. While previous studies on polycrystalline samples have identified a 105 K phase transition with a pronounced electronic and magnetic response but weak lattice character, no consensus on the origin of this transition has been reached. Here we show using synchrotron x-ray diffraction on high-pO2 floating-zone grown single crystals that this transition is driven by a real space …
Electronic Origin of Density Wave Orders in a Trilayer Nickelate
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理国家实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-Sen University（中山大学物理学院广东省磁电物理与器件重点实验室）；Technical Institute of Physics and Chemistry, Chinese Academy of Sciences（中国科学院化学物理研究所）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
Theoretical analysis on the possibility of superconductivity in a trilayer Ruddlesden-Popper nickelate La$_4$Ni$_3$O$_{10}$ under pressure and its experimental examination: comparison with La$_3$Ni$_2$O$_7$
Spectroscopic evidence for polaronic behaviour of the strong spin-orbit insulator Sr$_3$Ir$_2$O$_7$
本文利用温度依赖角分辨光电子能谱研究了双层Ruddlesden-Popper铱酸盐Sr $_3$ Ir $_2$ O $_7$。我们发现一个窄间隙相关绝缘体，与极化基态的光谱特征指示，惊人的相似，以前观察到的铜酸盐超导体的母体化合物。我们还观察到类似的行为为单层表弟Sr $_2$ IrO $_4$，表明强电子-玻色子耦合占主导地位的低能量激发这种异国情调的家庭的材料，并提供了一个微观之间的联系绝缘基态的完全不同的3D铜酸盐和5D铱酸盐。
Distinguishing Electronic Band Structure of Single-layer and Bilayer Ruddlesden-Popper Nickelates Probed by in-situ High Pressure X-ray Absorption Near-edge Spectroscopy
Electronic structure, magnetic correlations, and superconducting pairing in the reduced Ruddlesden-Popper bilayer La$_3$Ni$_2$O$_6$ under pressure: different role of $d_{3z^2-r^2}$ orbital compared with La$_3$Ni$_2$O$_7$
The tri-layer La$_{3-3x}$Sr$_{1+3x}$Mn$_{3}$O$_{10}$ manganites of Ruddlesden-Popper (RP) series are naturally arranged layered structure with alternate stacking of m-MnO$_2$ (m = 3) planes and rock-salt type block layers (La, Sr)$_2$O$_2$ along c-axis. The dimensionality of the RP series manganites depends on the number of perovskite layers and significantly affects the magnetic and transport properties of the system. The tri-layer La$_{2.1}$Sr$_{1.9}$Mn$_{3}$O$_{10}$ shows second-order magnetic phase transition. The critical behavior of phase transition has been studied around the transition…
Imaging the evolution of metallic states in a spin-orbit interaction driven correlated iridate
Ruddlesden-Popper（RP）系列的虹彩酸盐（Srn+1 IrnO 3 n +1）最近受到了广泛关注，这是由于自旋-轨道（SO）驱动的能带分裂和库仑相互作用的协同作用所产生的涌现物理的预期[1-3]。然而，关于相关性在电荷间隙形成中的作用的持续争论以及缺乏对掺杂对低能电子结构的影响的理解阻碍了实现许多预测状态的实验进展[4-8]，包括可能的高Tc超导性[7，9]。使用扫描隧道光谱，我们映射出的n=2 RP成员，Sr 3 Ir 2 O 7（Ir 327）的空间分辨态密度。我们发现，Ir 327的母体化合物，认为只存在作为一个弱相关的带绝缘体，实际上具有大量的~ 130 meV的电荷激发间隙驱动的结构，SO耦合和相关性之间的相互作用。在区分内的非均匀纹理电子结构的固有电子字符的一个关键组成部分是我们的识别的签名失踪的顶端氧缺陷，这在许多层状氧化物中发挥了关键作用。我们的测量结合从计算的见解揭示了顶端氧空位转移光谱重量从较高的能量的间隙能量，从而揭示了一个路径，以获得金属的电子状态从父母绝缘状态的虹膜。
Spin-density-wave transition in monolayer-trilayer La3Ni2O7 single crystals
ShanghaiTech University（上海科技大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Beijing National Laboratory for Condensed Matter Physics（北京凝聚态物理国家研究中心）；University of Chinese Academy of Sciences（中国科学院大学）；Center for High Pressure Science and Technology Advanced Research（高压科学先进研究发展中心）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree)（极端环境材料前沿研究上海市重点实验室）；Institute for Shanghai Advanced Research in Physical Sciences (SHARPS)（上海高等研究院物理科学研究所）；ShanghaiTech Laboratory for Topological Physics（上海科技大学拓扑物理实验室）；Shanghai Key Laboratory of High-resolution Electron Microscopy（高分辨电子显微学上海市重点实验室）；Department of Physics, Clarendon Laboratory, University of Oxford（牛津大学克拉伦登实验室物理系）；School of Physical Sciences, Great Bay University（大湾区大学物理科学学院）
Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5$d$ Transition Metal Oxides Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ ($n$=1, 2, and $\infty$)
我们利用光谱学和第一性原理计算研究了5 $d$ Ruddlesden-Popper系列Sr $_{n+1}$ Ir $_{n}$ O $_{3n+1}$（$n$ =1，2和$\infty$）的电子结构.由于5个$d$轨道在空间上比3个$d$或4个$d$轨道延伸得更远，因此人们普遍认为5个$d$化合物中的相关效应最小。然而，当我们增加$n$时，我们观察到从Mott绝缘体到金属的带宽控制过渡。此外，人工合成的钙钛矿SrIrO $_{3}$显示出约6的非常大的质量增强，表明其处于相关金属状态。
The similarities to cuprates make iridates an interesting potential platform for investigating superconductivity. Equally attractive are their puzzling complex intrinsic interactions. Here, we report an ultrafast optical spectroscopy investigation of a coherent phonon mode in Sr3Ir2O7, a bilayer Ruddlesden-Popper perovskite iridate. An anomaly in the A1g optical phonon (ν = 4.4 THz) is unambiguously observed below the Néel temperature (TN), which we attribute to pseudospin-lattice coupling (PLC). Significantly, we find that PLC is the dominant interaction at low temperature, and we directly me…
