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Wang HH, Xiong Y, Padma H, Wang Y, Wang Z, Claes R, Brunin G, Min L, Zu R, Wetherington MT, Wang Y, Mao Z, Hautier G, Chen LQ, Dabo I, Gopalan V. Strong electron-phonon coupling driven pseudogap modulation and density-wave fluctuations in a correlated polar metal. Nat Commun 2023; 14:5769. [PMID: 37723139 PMCID: PMC10507017 DOI: 10.1038/s41467-023-41460-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 09/01/2023] [Indexed: 09/20/2023] Open
Abstract
There is tremendous interest in employing collective excitations of the lattice, spin, charge, and orbitals to tune strongly correlated electronic phenomena. We report such an effect in a ruthenate, Ca3Ru2O7, where two phonons with strong electron-phonon coupling modulate the electronic pseudogap as well as mediate charge and spin density wave fluctuations. Combining temperature-dependent Raman spectroscopy with density functional theory reveals two phonons, B2P and B2M, that are strongly coupled to electrons and whose scattering intensities respectively dominate in the pseudogap versus the metallic phases. The B2P squeezes the octahedra along the out of plane c-axis, while the B2M elongates it, thus modulating the Ru 4d orbital splitting and the bandwidth of the in-plane electron hopping; Thus, B2P opens the pseudogap, while B2M closes it. Moreover, the B2 phonons mediate incoherent charge and spin density wave fluctuations, as evidenced by changes in the background electronic Raman scattering that exhibit unique symmetry signatures. The polar order breaks inversion symmetry, enabling infrared activity of these phonons, paving the way for coherent light-driven control of electronic transport.
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Affiliation(s)
- Huaiyu Hugo Wang
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Yihuang Xiong
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA
| | - Hari Padma
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yi Wang
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Ziqi Wang
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Romain Claes
- Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Chemin des Étoiles 8, B-1348, Louvain-la-Neuve, Belgium
| | | | - Lujin Min
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Rui Zu
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Maxwell T Wetherington
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yu Wang
- 2D Crystal Consortium, Material Research Institute, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Zhiqiang Mao
- 2D Crystal Consortium, Material Research Institute, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Geoffroy Hautier
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA
- Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Chemin des Étoiles 8, B-1348, Louvain-la-Neuve, Belgium
| | - Long-Qing Chen
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Ismaila Dabo
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Venkatraman Gopalan
- Materials Research Institute and Department of Material Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
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Carbin T, Zhang X, Culver AB, Zhao H, Zong A, Acharya R, Abbamonte CJ, Roy R, Cao G, Kogar A. Evidence for Bootstrap Percolation Dynamics in a Photoinduced Phase Transition. PHYSICAL REVIEW LETTERS 2023; 130:186902. [PMID: 37204876 DOI: 10.1103/physrevlett.130.186902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/27/2023] [Accepted: 03/30/2023] [Indexed: 05/21/2023]
Abstract
Upon intense femtosecond photoexcitation, a many-body system can undergo a phase transition through a nonequilibrium route, but understanding these pathways remains an outstanding challenge. Here, we use time-resolved second harmonic generation to investigate a photoinduced phase transition in Ca_{3}Ru_{2}O_{7} and show that mesoscale inhomogeneity profoundly influences the transition dynamics. We observe a marked slowing down of the characteristic time τ that quantifies the transition between two structures. τ evolves nonmonotonically as a function of photoexcitation fluence, rising from below 200 fs to ∼1.4 ps, then falling again to below 200 fs. To account for the observed behavior, we perform a bootstrap percolation simulation that demonstrates how local structural interactions govern the transition kinetics. Our work highlights the importance of percolating mesoscale inhomogeneity in the dynamics of photoinduced phase transitions and provides a model that may be useful for understanding such transitions more broadly.
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Affiliation(s)
- Tyler Carbin
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
| | - Xinshu Zhang
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
| | - Adrian B Culver
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
- Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Hengdi Zhao
- Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Alfred Zong
- Department of Chemistry, University of California at Berkeley, Berkeley, California, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Rishi Acharya
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
| | - Cecilia J Abbamonte
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
| | - Rahul Roy
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
- Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Gang Cao
- Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Anshul Kogar
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA
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Petkov V, Rao TD, Zafar A, Abeykoon AMM, Fletcher E, Peng J, Mao ZQ, Ke X. Lattice distortions and the metal-insulator transition in pure and Ti-substituted Ca 3Ru 2O 7. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 51:015402. [PMID: 36301709 DOI: 10.1088/1361-648x/ac9dda] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
We report pair distribution function studies on the relationship between the metal-insulator transition (MIT) and lattice distortions in pure and Ti-substituted bilayer Ca3Ru2O7. Structural refinements performed as a function of temperature, magnetic field and length scale reveal the presence of lattice distortions not only within but also orthogonal to the bilayers. Because of the distortions, the local and average crystal structure differ across a broad temperature region extending from room temperature to temperatures below the MIT. The coexistence of distinct lattice distortions is likely to be behind the marked structural flexibility of Ca3Ru2O7under external stimuli. This observation highlights the ubiquity of lattice distortions in an archetypal Mott system and calls for similar studies on other families of strongly correlated materials.
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Affiliation(s)
- V Petkov
- Department of Physics, Central Michigan University, Mt. Pleasant, MI 48858, United States of America
| | - T Durga Rao
- Department of Physics, Central Michigan University, Mt. Pleasant, MI 48858, United States of America
- Department of Physics, GITAM, Visakhapatnam, Andhra Pradesh 530045, India
| | - A Zafar
- Department of Physics, Central Michigan University, Mt. Pleasant, MI 48858, United States of America
| | - A M Milinda Abeykoon
- Photon Sciences Division, Brookhaven National Laboratory, Upton, NY 11973, United States of America
| | - E Fletcher
- Department Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States of America
| | - J Peng
- School of Physics, Southeast University, Nanjin, People's Republic of China
| | - Z Q Mao
- Department of Physics, Pennsylvania State University, University Park, State College, PA 16802, United States of America
| | - X Ke
- Department Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States of America
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Electronically driven spin-reorientation transition of the correlated polar metal Ca 3Ru 2O 7. Proc Natl Acad Sci U S A 2020; 117:15524-15529. [PMID: 32576687 DOI: 10.1073/pnas.2003671117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The interplay between spin-orbit coupling and structural inversion symmetry breaking in solids has generated much interest due to the nontrivial spin and magnetic textures which can result. Such studies are typically focused on systems where large atomic number elements lead to strong spin-orbit coupling, in turn rendering electronic correlations weak. In contrast, here we investigate the temperature-dependent electronic structure of [Formula: see text], a [Formula: see text] oxide metal for which both correlations and spin-orbit coupling are pronounced and in which octahedral tilts and rotations combine to mediate both global and local inversion symmetry-breaking polar distortions. Our angle-resolved photoemission measurements reveal the destruction of a large hole-like Fermi surface upon cooling through a coupled structural and spin-reorientation transition at 48 K, accompanied by a sudden onset of quasiparticle coherence. We demonstrate how these result from band hybridization mediated by a hidden Rashba-type spin-orbit coupling. This is enabled by the bulk structural distortions and unlocked when the spin reorients perpendicular to the local symmetry-breaking potential at the Ru sites. We argue that the electronic energy gain associated with the band hybridization is actually the key driver for the phase transition, reflecting a delicate interplay between spin-orbit coupling and strong electronic correlations and revealing a route to control magnetic ordering in solids.
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Shao DF, Zhang SH, Gurung G, Yang W, Tsymbal EY. Nonlinear Anomalous Hall Effect for Néel Vector Detection. PHYSICAL REVIEW LETTERS 2020; 124:067203. [PMID: 32109084 DOI: 10.1103/physrevlett.124.067203] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/23/2020] [Indexed: 06/10/2023]
Abstract
Antiferromagnetic (AFM) spintronics exploits the Néel vector as a state variable for novel spintronic devices. Recent studies have shown that the fieldlike and antidamping spin-orbit torques (SOTs) can be used to switch the Néel vector in antiferromagnets with proper symmetries. However, the precise detection of the Néel vector remains a challenging problem. In this Letter, we predict that the nonlinear anomalous Hall effect (AHE) can be used to detect the Néel vector in most compensated antiferromagnets supporting the antidamping SOT. We show that the magnetic crystal group symmetry of these antiferromagnets combined with spin-orbit coupling produce a sizable Berry curvature dipole and hence the nonlinear AHE. As a specific example, we consider the half-Heusler alloy CuMnSb, in which the Néel vector can be switched by the antidamping SOT. Based on density-functional theory calculations, we show that the nonlinear AHE in CuMnSb results in a measurable Hall voltage under conventional experimental conditions. The strong dependence of the Berry curvature dipole on the Néel vector orientation provides a new detection scheme of the Néel vector based on the nonlinear AHE. Our predictions enrich the material platform for studying nontrivial phenomena associated with the Berry curvature and broaden the range of materials useful for AFM spintronics.
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Affiliation(s)
- Ding-Fu Shao
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0299, USA
| | - Shu-Hui Zhang
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Gautam Gurung
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0299, USA
| | - Wen Yang
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0299, USA
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Xu X, Peng J, Zhang J, Ma Z, Chen C, Han J, Liu B, Lin L, Wu X, Mao Z, Qu Z, Sheng Z. Optical spectroscopy study of Ca 3(Ru 0.91Mn 0.09) 2O 7 single crystal in high magnetic fields. Sci Bull (Beijing) 2019; 64:20-25. [PMID: 36659519 DOI: 10.1016/j.scib.2018.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/21/2018] [Accepted: 11/15/2018] [Indexed: 01/21/2023]
Abstract
The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca3(Ru0.91Mn0.09)2O7 (CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-metal transitions (IMTs) are observed via magneto-optical properties of the crystal. The critical magnetic field (H // c) of IMT for CRMO is found to be as large as 35 T at 5 K. The fine structure of optical spectra identified the antiferromagnetic/ferro-orbital-ordering configurations of Ru 4d orbitals at low temperatures. Meanwhile, the configuration of orbital polarization of such double-layer CRMO single crystal is discussed. These results suggest that the orbital degree of freedom plays an important role in the field induced IMT of multi-orbital system.
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Affiliation(s)
- Xueli Xu
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230026, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jin Peng
- School of Physics, Southeast University, Nanjing 211189, China
| | - Junpei Zhang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zongwei Ma
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Cheng Chen
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Junbo Han
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Bingjie Liu
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230026, China
| | - Lingfang Lin
- School of Physics, Southeast University, Nanjing 211189, China
| | - Xiaoshan Wu
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China; School of Physics, Nanjing University, Nanjing 210093, China
| | - Zhiqiang Mao
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118, USA
| | - Zhe Qu
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China.
| | - Zhigao Sheng
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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Thöle F, Spaldin NA. Magnetoelectric multipoles in metals. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0450. [PMID: 30373940 PMCID: PMC6232580 DOI: 10.1098/rsta.2017.0450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/11/2018] [Indexed: 06/08/2023]
Abstract
In this paper, we demonstrate computationally the existence of magnetoelectric multipoles, arising from the second-order term in the multipole expansion of a magnetization density in a magnetic field, in non-centrosymmetric magnetic metals. While magnetoelectric multipoles have long been discussed in the context of the magnetoelectric effect in non-centrosymmetric magnetic insulators, they have not previously been identified in metallic systems, in which the mobile carriers screen any electrical polarization. Using first-principles density functional calculations, we explore three specific systems: first, a conventional centrosymmetric magnetic metal, Fe, in which we break inversion symmetry by introducing a surface, which both generates magnetoelectric monopoles and allows a perpendicular magnetoelectric response. Next, the hypothetical cation-ordered perovskite, SrCaRu2O6, in which we study the interplay between the magnitude of the polar symmetry breaking and that of the magnetic dipoles and multipoles, finding that both scale proportionally to the structural distortion. Finally, we identify a hidden antiferromultipolar order in the non-centrosymmetric, antiferromagnetic metal Ca3Ru2O7, and show that, while its competing magnetic phases have similar magnetic dipolar structures, their magnetoelectric multipolar structures are distinctly different, reflecting the strong differences in transport properties.This article is part of the theme issue 'Celebrating 125 years of Oliver Heaviside's 'Electromagnetic Theory''.
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Affiliation(s)
- Florian Thöle
- Materials Theory, ETH Zürich,Wolfgang-Pauli-Strasse 27, Zürich 8093, Switzerland
| | - Nicola A Spaldin
- Materials Theory, ETH Zürich,Wolfgang-Pauli-Strasse 27, Zürich 8093, Switzerland
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Halwidl D, Mayr-Schmölzer W, Setvin M, Fobes D, Peng J, Mao Z, Schmid M, Mittendorfer F, Redinger J, Diebold U. A full monolayer of superoxide: oxygen activation on the unmodified Ca 3Ru 2O 7(001) surface. JOURNAL OF MATERIALS CHEMISTRY. A 2018; 6:5703-5713. [PMID: 30009023 PMCID: PMC6003542 DOI: 10.1039/c8ta00265g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/04/2018] [Indexed: 05/20/2023]
Abstract
Activating the O2 molecule is at the heart of a variety of technological applications, most prominently in energy conversion schemes including solid oxide fuel cells, electrolysis, and catalysis. Perovskite oxides, both traditionally-used and novel formulations, are the prime candidates in established and emerging energy devices. This work shows that the as-cleaved and unmodified CaO-terminated (001) surface of Ca3Ru2O7, a Ruddlesden-Popper perovskite, supports a full monolayer of superoxide ions, O2-, when exposed to molecular O2. The electrons for activating the molecule are transferred from the subsurface RuO2 layer. Theoretical calculations using both, density functional theory (DFT) and more accurate methods (RPA), predict the adsorption of O2- with Eads = 0.72 eV and provide a thorough analysis of the charge transfer. Non-contact atomic force microscopy (nc-AFM) and scanning tunnelling microscopy (STM) are used to resolve single molecules and confirm the predicted adsorption structures. Local contact potential difference (LCPD) and X-ray photoelectron spectroscopy (XPS) measurements on the full monolayer of O2- confirm the negative charge state of the molecules. The present study reports the rare case of an oxide surface without dopants, defects, or low-coordinated sites readily activating molecular O2.
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Affiliation(s)
- Daniel Halwidl
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
| | - Wernfried Mayr-Schmölzer
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
- Center for Computational Materials Science , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria
| | - Martin Setvin
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
| | - David Fobes
- Department of Physics and Engineering Physics , Tulane University , 2001 Percival Stern Hall , New Orleans , LA 70118 , USA
| | - Jin Peng
- Department of Physics and Engineering Physics , Tulane University , 2001 Percival Stern Hall , New Orleans , LA 70118 , USA
| | - Zhiqiang Mao
- Department of Physics and Engineering Physics , Tulane University , 2001 Percival Stern Hall , New Orleans , LA 70118 , USA
| | - Michael Schmid
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
| | - Florian Mittendorfer
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
- Center for Computational Materials Science , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria
| | - Josef Redinger
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
- Center for Computational Materials Science , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria
| | - Ulrike Diebold
- Institute of Applied Physics , TU Wien , Wiedner Hauptstrasse 8-10/134 , 1040 Vienna , Austria .
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Zhu M, Hong T, Peng J, Zou T, Mao ZQ, Ke X. Field-induced magnetic phase transitions and memory effect in bilayer ruthenate Ca 3Ru 2O 7 with Fe substitution. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:075802. [PMID: 29359709 DOI: 10.1088/1361-648x/aaa626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bilayer ruthenate Ca3(Ru1-x Fe x )2O7 (x = 0.05) exhibits an incommensurate magnetic soliton lattice driven by the Dzyaloshinskii-Moriya interaction. Here we report complex field-induced magnetic phase transitions and memory effect in this system via single-crystal neutron diffraction and magnetotransport measurements. We observe first-order incommensurate-to-commensurate magnetic transitions upon applying the magnetic field both along and perpendicular to the propagation axis of the incommensurate spin structure. Furthermore, we find that the metastable states formed upon decreasing the magnetic field depend on the temperature and the applied field orientation. We suggest that the observed field-induced metastability may be ascribable to the quenched kinetics at low temperature.
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Affiliation(s)
- M Zhu
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States of America
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10
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Abstract
As complex ternary perovskite-type oxides are increasingly used in solid oxide fuel cells, electrolysis and catalysis, it is desirable to obtain a better understanding of their surface chemical properties. Here we report a pronounced ordering of hydroxyls on the cleaved (001) surface of the Ruddlesden-Popper perovskite Ca3Ru2O7 upon water adsorption at 105 K and subsequent annealing to room temperature. Density functional theory calculations predict the dissociative adsorption of a single water molecule (Eads = 1.64 eV), forming an (OH)ads group adsorbed in a Ca-Ca bridge site, with an H transferred to a neighboring surface oxygen atom, Osurf. Scanning tunneling microscopy images show a pronounced ordering of the hydroxyls with (2 × 1), c(2 × 6), (1 × 3), and (1 × 1) periodicity. The present work demonstrates the importance of octahedral rotation and tilt in perovskites, for influencing surface reactivity, which here induces the ordering of the observed OH overlayers. As ternary perovskite-type oxides are increasingly used in fuel cells and catalysis, greater understanding of their surface chemical properties is required. Here the authors report a pronounced ordering of hydroxyls on the cleaved (001) surface of Ca3Ru2O7 perovskite induced by O-octahedral rotation and tilt.
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Zhu M, Peng J, Zou T, Prokes K, Mahanti SD, Hong T, Mao ZQ, Liu GQ, Ke X. Colossal Magnetoresistance in a Mott Insulator via Magnetic Field-Driven Insulator-Metal Transition. PHYSICAL REVIEW LETTERS 2016; 116:216401. [PMID: 27284665 DOI: 10.1103/physrevlett.116.216401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Indexed: 06/06/2023]
Abstract
We present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca_{3}Ru_{2}O_{7}. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.
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Affiliation(s)
- M Zhu
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - J Peng
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - T Zou
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - K Prokes
- Helmholtz Zentrum Berlin, D-14109 Berlin, Germany
| | - S D Mahanti
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - T Hong
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z Q Mao
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - G Q Liu
- Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - X Ke
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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12
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Magnetic phase separation in double layer ruthenates Ca3(Ru(1-x)Ti(x))2O7. Sci Rep 2016; 6:19462. [PMID: 26771083 PMCID: PMC4725874 DOI: 10.1038/srep19462] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 12/08/2015] [Indexed: 11/08/2022] Open
Abstract
A phase transition from metallic AFM-b antiferromagnetic state to Mott insulating G-type antiferromagnetic (G-AFM) state was found in Ca3(Ru1−xTix)2O7 at about x = 0.03 in our previous work. In the present, we focused on the study of the magnetic transition near the critical composition through detailed magnetization measurements. There is no intermediate magnetic phases between the AFM-b and G-AFM states, which is in contrasted to manganites where a similar magnetic phase transition takes place through the presence of several intermediate magnetic phases. The AFM-b-to-G-AFM transition in Ca3(Ru1−xTix)2O7 happens through a phase separation process in the 2–5% Ti range, whereas similar magnetic transitions in manganites are tuned by 50–70% chemical substitutions. We discussed the possible origin of such an unusual magnetic transition and compared with that in manganites.
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David R, Kabbour H, Filimonov D, Huvé M, Pautrat A, Mentré O. Reversible Topochemical Exsolution of Iron in BaFe2+2(PO4)2. Angew Chem Int Ed Engl 2014; 53:13365-70. [DOI: 10.1002/anie.201404476] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/07/2014] [Indexed: 11/10/2022]
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David R, Kabbour H, Filimonov D, Huvé M, Pautrat A, Mentré O. Reversible Topochemical Exsolution of Iron in BaFe2+2(PO4)2. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404476] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Liu M, Zou Q, Ma C, Collins G, Mi SB, Jia CL, Guo H, Gao H, Chen C. Strain-induced anisotropic transport properties of LaBaCo₂O₅.₅+δ thin films on NdGaO₃ substrates. ACS APPLIED MATERIALS & INTERFACES 2014; 6:8526-8530. [PMID: 24824560 DOI: 10.1021/am502448k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Thin films of double-perovskite structural LaBaCo2O5.5+δ were epitaxially grown on (110) NdGaO3 substrates by pulsed laser deposition. Microstructural studies by high-resolution X-ray diffraction and transmission electron microscopy revealed that the films have an excellent quality epitaxial structure. In addition, strong in-plane anisotropic strains were measured. Electrical transport properties of the films were characterized by an ultra-high-vacuum four-probe scanning tunneling microscopy system at different temperatures. It was found that the anisotropic in-plane strain can significantly tune the values of film resistance up to 590%.
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Affiliation(s)
- Ming Liu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University , Xi'an 710049, People's Republic of China
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Liu M, Ma C, Liu J, Collins G, Chen C, He J, Jiang J, Meletis EI, Sun L, Jacobson AJ, Whangbo MH. Giant magnetoresistance and anomalous magnetic properties of highly epitaxial ferromagnetic LaBaCo2O(5.5+δ) thin films on (001) MgO. ACS APPLIED MATERIALS & INTERFACES 2012; 4:5524-5528. [PMID: 22967042 DOI: 10.1021/am301427c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Ferromagnetic thin films of the A-site nano-ordered double perovskite LaBaCo(2)O(5.5+δ) (LBCO) were grown on (001) MgO, and their structural and magnetic properties were characterized. The as-grown films have an excellent epitaxial behavior with atomically sharp interfaces, with the c-axis of the LBCO structure lying in the film plane and the interface relationship given by (100)(LBCO)//(001)(MgO) and [001](LBCO)//[100](MgO) or [010](MgO). The as-grown LBCO films exhibit a giant magnetoresistance (54% at 40 K under 7 T) and an anomalous magnetic hysteresis, depending strongly on the temperature and the applied magnetic field scan width.
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Affiliation(s)
- Ming Liu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
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Kabbour H, David R, Pautrat A, Koo HJ, Whangbo MH, André G, Mentré O. A Genuine Two-Dimensional Ising Ferromagnet with Magnetically Driven Re-entrant Transition. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205843] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Kabbour H, David R, Pautrat A, Koo HJ, Whangbo MH, André G, Mentré O. A Genuine Two-Dimensional Ising Ferromagnet with Magnetically Driven Re-entrant Transition. Angew Chem Int Ed Engl 2012; 51:11745-9. [DOI: 10.1002/anie.201205843] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 08/31/2012] [Indexed: 11/11/2022]
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