Orbital selective switching of ferromagnetism in an oxide quasi two-dimensional electron gas
R. Di Capua, M. Verma, M. Radovic, V. N. Strocov, C. Piamonteze, E. B. Guedes, N. Plumb, Yu Chen, M. D'Antuono, G. M. De Luca, E. Di Gennaro, D. Stornaiuolo, D.… 展开作者
R. Di Capua, M. Verma, M. Radovic, V. N. Strocov, C. Piamonteze, E. B. Guedes, N. Plumb, Yu Chen, M. D'Antuono, G. M. De Luca, E. Di Gennaro, D. Stornaiuolo, D. Preziosi, B. Jouault, F. Miletto Granozio, A. Sambri, R. Pentcheva, G. Ghiringhelli, M. Salluzzo
Multi-orbital physics in quasi-two-dimensional electron gases (q2DEGs) triggers unique phenomena not observed in bulk materials, such as unconventional superconductivity and magnetism. Here, we investigate the mechanism of orbital selective switching of the spin-polarization in the oxide q2DEG formed at the (001) interface between the LaAlO$_{3}$, EuTiO$_{3}$ and SrTiO$_{3}$ band insulators. By using density functional theory calculations, transport, magnetic and x-ray spectroscopy measurements, we find that the filling of titanium-bands with 3d$_{xz,yz}$ orbital character in the EuTiO3 layer and at the interface with SrTiO$_{3}$ induces an antiferromagnetic to ferromagnetic switching of the exchange interaction between Eu-4f$^{7}$ magnetic moments. The results explain the observation of the carrier density dependent ferromagnetic correlations and anomalous Hall effect in this q2DEG, and demonstrate how combined theoretical and experimental approaches can lead to a deeper understanding of novel electronic phases and serve as a guide for the materials design for advanced electronic applications.
Inducing ferromagnetism by structural engineering in a strongly spin-orbit coupled oxide
Universität Würzburg（维尔茨堡大学）；International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；CNR-SPIN, UOS Salerno（萨莱诺国家研究委员会自旋单元）；Leibniz Institute for Solid State and Materials Research Dresden（德累斯顿莱布尼兹固体与材料研究所）；TU Dresden（德累斯顿工业大学）；Synchrotron SOLEIL（索雷尔同步辐射中心）
Exchange Interaction and $T_c$ in Alkaline-earth-metal-oxide-based DMS without Magnetic Impurities: First Principle Pseudo-SIC and Monte Carlo Calculation
通过第一性原理计算，探讨了碱土金属氧化物中引入碳原子诱导半金属铁磁性的前景。利用类赝势自相互作用修正的局域自旋密度方法计算了体系的电子结构和交换耦合常数，讨论了体系铁磁性的起源。居里温度（$T_c$）也通过采用蒙特卡罗模拟预测。结果表明，考虑电子自相互作用后，C在主体材料中诱导的半金属铁磁性比标准LDA情形更稳定，C的$2p$电子态在带隙中的局域化程度更高，短程交换作用占优势.虽然MgO $_{1-x}$ C $_x$中的铁磁性由于$1st$ -最近邻对的交换相互作用而稳定，并且可能在较高的$x$下被反铁磁性超交换相互作用抑制，但是CaO $_{1-x}$ C $_x$、SrO $_{1-x}$ C $_x$和BaO $_{1-x}$ C $_x$中的铁磁性通过$1st$ -和$2nd$ -最近邻对两者而稳定，而$T_c$随C浓度单调增加。
X-ray Anomalous Scattering of Diluted Magnetic Oxide Semiconductors: Possible Evidence of Lattice Deformation for High Temperature Ferromagnetism
我们研究了在金红石型和金红石型Ti_{1-x} $Co$ _{x} $O$ _{2-delta} $ thin films that exhibit room-temperature ferromagnetism. Intensities of the x-ray Bragg reflection from the films were measured around the $ K $-absorption-edge of Co. If the Co ions randomly substitute on the Ti sites, the intensity should exhibit an anomaly due to the anomalous dispersion of the atomic scattering factor of Co. However, none of the anatase and rutile samples did exhibit an anomaly, unambiguously showing that the Co ions in Ti$ _{1-x} $Co$ _{x} $O$ _{2-delta} $ are not exactly located at the Ti sites of TiO$ _2 $. The absence …
A machine learning-based selective sampling procedure for identifying the low energy region in a potential energy surface: a case study on proton conduction in oxides
Charge transfer and competing symmetry breaking drive orbital reconstruction and emergent ferromagnetism in insulating oxide superlattices
Indian Institute of Science（印度科学学院）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器中心）；ALBA Synchrotron Light Source（阿尔巴同步辐射光源）；Advanced Photon Source, Argonne National Laboratory（阿贡国家实验室先进光子源）
Effect of iron-doping on spin-state transition and ferromagnetism in Pr$_{0.5}$Ca$_{0.5}$CoO$_{3-δ}$ cobalt oxides
对多晶Pr $_{0.5}$ Ca $_{0.5}$ Co $_{1-x}$ Fe $_{x}$ O $_{3-δ}$（$x$ = 0、0.05、0.10和0.15）样品进行电阻率和直流磁化测量。所制备的样品表现出铁磁（FM）转变，转变温度随着铁掺杂量的增加而增加。高氧压退火诱导了\emph{iron-free}样品中Co离子的自旋态转变，并且这种转变随着退火氧压的增加而增强，而高氧压退火抑制了铁磁有序。与\emph{iron-free}样品的情况相反，\emph{iron-doped}样品在高氧压下退火没有引起自旋态转变，并且铁磁转变温度几乎与退火过程无关。\emph{iron-free}样品在高氧压下退火后自旋态转变的增强应归因于晶胞体积的减小。Fe掺杂对自旋态跃迁的抑制与晶胞体积的增大以及Fe-O键比Co-O键强有关。铁掺杂对铁磁性的增强可能源于Fe $^{3+}$和Co $^{4+}$之间通过氧的铁磁交换相互作用（Fe $^{3+}$ -O-Co $^{4+}$）。
Site-Selective Oxygen Vacancy Formation Derived from the Characteristic Crystal Structures of in Sn-Nb complex Oxides
二价锡氧化物作为一种新型的p型氧化物半导体材料，已经引起了人们的广泛关注，它对于实现未来的氧化物电子器件至关重要。最近，开发了p型Sn 2Nb 2 O 7和SnNb 2 O 6;然而，实际应用需要通过降低缺陷浓度来增强空穴迁移率。在这项工作中，我们研究了可能降低空穴产生效率和空穴迁移率的氧空位的形成与Sn-Nb复合氧化物的晶体结构之间的关系。扩展的X-射线吸收精细结构光谱和Rietveld分析的X-射线衍射显示，在O位键合的锡离子在两个锡的氧化物中的氧空位的优先形成。此外，在p型Sn 2Nb 2 O 7中发现Sn离子周围的大量氧空位，从而表明氧空位对低空穴产生效率的影响。氧空位的形成对晶体结构的依赖性可以从基于键价和和德拜温度评估的Sn-O键强度来阐明。两种Sn-Nb复合氧化物的键强度差异与Sn 2+的空间位阻和电子密度的不对称性有关。这表明材料设计的重要性，重点是Sn离子周围的局部结构，以防止在p型Sn 2+氧化物中形成氧空位。
Phase-selective growth of water-soluble strontium aluminate via sputtering deposition for freestanding oxide membranes
TU Wien（维也纳工业大学）；Université Caen Normandie（诺曼底大学）；CEA（法国原子能和替代能源委员会）；ENSICAEN（恩西西安高等学院）；CNRS（法国国家科学研究中心）；CIMAP UMR6252（CIMAP联合研究实验室6252）；Catalan Institute of Nanoscience and Nanotechnology (ICN2)（加泰罗尼亚纳米科学和纳米技术研究所）；CSIC（西班牙国家研究委员会）；BIST（巴塞罗那科学与技术研究院）；University of Geneva（日内瓦大学）；Leibniz-Institut für Kristallzüchtung（莱布尼兹晶体生长研究所）；ALBA Synchrotron Light Source（阿尔巴同步辐射光源）
Plasmonic Photocatalysis Enables Selective Oxidative Coupling of Methane with Nitrous Oxide under Ambient Conditions
Stanford University School of Engineering（斯坦福大学工程学院）；Boston College（波士顿学院）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Stanford University School of Medicine（斯坦福大学医学院）
