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Stepanov EA. Eliminating Orbital Selectivity from the Metal-Insulator Transition by Strong Magnetic Fluctuations. PHYSICAL REVIEW LETTERS 2022; 129:096404. [PMID: 36083639 DOI: 10.1103/physrevlett.129.096404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
The orbital-selective electronic behavior is one of the most remarkable manifestations of strong electronic correlations in multiorbital systems. A prominent example is the orbital-selective Mott transition (OSMT), which is characterized by the coexistence of localized electrons in some orbitals, and itinerant electrons in other orbitals. The state-of-the-art theoretical description of the OSMT in two- and three-dimensional systems is based on local nonperturbative approximations to electronic correlations provided by dynamical mean-field theory or slave spin method. In this work we go beyond this local picture and focus on the effect of spatial collective electronic fluctuations on the OSMT. To this aim, we consider a half-filled Hubbard-Kanamori model on a cubic lattice with two orbitals that have different bandwidths. We show that strong magnetic fluctuations that are inherent in this system prevent the OSMT and favor the Néel transition that occurs at the same critical temperature for both orbitals.
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Affiliation(s)
- Evgeny A Stepanov
- CPHT, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, F-91128 Palaiseau, France
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2
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Lin LF, Zhang Y, Alvarez G, Moreo A, Dagotto E. Origin of Insulating Ferromagnetism in Iron Oxychalcogenide Ce_{2}O_{2}FeSe_{2}. PHYSICAL REVIEW LETTERS 2021; 127:077204. [PMID: 34459630 DOI: 10.1103/physrevlett.127.077204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
An insulating ferromagnetic (FM) phase exists in the quasi-one-dimensional iron oxychalcogenide Ce_{2}O_{2}FeSe_{2}, but its origin is unknown. To understand the FM mechanism, here a systematic investigation of this material is provided, analyzing the competition between ferromagnetic and antiferromagnetic tendencies and the interplay of hoppings, Coulomb interactions, Hund's coupling, and crystal-field splittings. Our intuitive analysis based on second-order perturbation theory shows that large entanglements between doubly occupied and half filled orbitals play a key role in stabilizing the FM order in Ce_{2}O_{2}FeSe_{2}. In addition, via many-body computational techniques applied to a multiorbital Hubbard model, the phase diagram confirms the proposed FM mechanism.
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Affiliation(s)
- Ling-Fang Lin
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Yang Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Gonzalo Alvarez
- Computational Sciences and Engineering Division and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Adriana Moreo
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Elbio Dagotto
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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3
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Interaction-induced topological phase transition and Majorana edge states in low-dimensional orbital-selective Mott insulators. Nat Commun 2021; 12:2955. [PMID: 34011947 PMCID: PMC8134496 DOI: 10.1038/s41467-021-23261-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 04/21/2021] [Indexed: 11/08/2022] Open
Abstract
Topological phases of matter are among the most intriguing research directions in Condensed Matter Physics. It is known that superconductivity induced on a topological insulator's surface can lead to exotic Majorana modes, the main ingredient of many proposed quantum computation schemes. In this context, the iron-based high critical temperature superconductors are a promising platform to host such an exotic phenomenon in real condensed-matter compounds. The Coulomb interaction is commonly believed to be vital for the magnetic and superconducting properties of these systems. This work bridges these two perspectives and shows that the Coulomb interaction can also drive a canonical superconductor with orbital degrees of freedom into the topological state. Namely, we show that above a critical value of the Hubbard interaction the system simultaneously develops spiral spin order, a highly unusual triplet amplitude in superconductivity, and, remarkably, Majorana fermions at the edges of the system.
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Herbrych J, Heverhagen J, Alvarez G, Daghofer M, Moreo A, Dagotto E. Block-spiral magnetism: An exotic type of frustrated order. Proc Natl Acad Sci U S A 2020; 117:16226-16233. [PMID: 32601231 PMCID: PMC7368323 DOI: 10.1073/pnas.2001141117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Competing interactions in quantum materials induce exotic states of matter such as frustrated magnets, an extensive field of research from both the theoretical and experimental perspectives. Here, we show that competing energy scales present in the low-dimensional orbital-selective Mott phase (OSMP) induce an exotic magnetic order, never reported before. Earlier neutron-scattering experiments on iron-based 123 ladder materials, where OSMP is relevant, already confirmed our previous theoretical prediction of block magnetism (magnetic order of the form [Formula: see text]). Now we argue that another phase can be stabilized in multiorbital Hubbard models, the block-spiral state. In this state, the magnetic islands form a spiral propagating through the chain but with the blocks maintaining their identity, namely rigidly rotating. The block-spiral state is stabilized without any apparent frustration, the common avenue to generate spiral arrangements in multiferroics. By examining the behavior of the electronic degrees of freedom, parity-breaking quasiparticles are revealed. Finally, a simple phenomenological model that accurately captures the macroscopic spin spiral arrangement is also introduced, and fingerprints for the neutron-scattering experimental detection are provided.
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Affiliation(s)
- J Herbrych
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996;
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
| | - J Heverhagen
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, D-70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, D-70550 Stuttgart, Germany
| | - G Alvarez
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - M Daghofer
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, D-70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, D-70550 Stuttgart, Germany
| | - A Moreo
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - E Dagotto
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
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5
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Herbrych J, Heverhagen J, Patel ND, Alvarez G, Daghofer M, Moreo A, Dagotto E. Novel Magnetic Block States in Low-Dimensional Iron-Based Superconductors. PHYSICAL REVIEW LETTERS 2019; 123:027203. [PMID: 31386537 DOI: 10.1103/physrevlett.123.027203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 05/09/2019] [Indexed: 06/10/2023]
Abstract
Inelastic neutron scattering recently confirmed the theoretical prediction of a ↑↑↓↓-magnetic state along the legs of quasi-one-dimensional iron-based ladders in the orbital-selective Mott phase (OSMP). We show here that electron doping of the OSMP induces a whole class of novel block states with a variety of periodicities beyond the previously reported π/2 pattern. We discuss the magnetic phase diagram of the OSMP regime that could be tested by neutrons once appropriate quasi-1D quantum materials with the appropriate dopings are identified.
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Affiliation(s)
- J Herbrych
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
| | - J Heverhagen
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - N D Patel
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - G Alvarez
- Computational Sciences and Engineering Division and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Daghofer
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - A Moreo
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E Dagotto
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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6
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Yu R, Zhu JX, Si Q. Orbital Selectivity Enhanced by Nematic Order in FeSe. PHYSICAL REVIEW LETTERS 2018; 121:227003. [PMID: 30547656 DOI: 10.1103/physrevlett.121.227003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/21/2018] [Indexed: 06/09/2023]
Abstract
Motivated by the recent low-temperature experiments on bulk FeSe, we study the electron correlation effects in a multiorbital model for this compound in the nematic phase using the U(1) slave-spin theory. We find that a finite nematic order helps to stabilize an orbital selective Mott phase. Moreover, we propose that when the d- and s-wave bond nematic orders are combined with the ferro-orbital order, there exists a surprisingly large orbital selectivity between the xz and yz orbitals even though the associated band splitting is relatively small. Our results explain the seemingly unusual observation of strong orbital selectivity in the nematic phase of FeSe, uncover new clues on the nature of the nematic order, and set the stage to elucidate the interplay between superconductivity and nematicity in iron-based superconductors.
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Affiliation(s)
- Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Jian-Xin Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Qimiao Si
- Department of Physics & Astronomy, Rice University, Houston, Texas 77005, USA
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7
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Abstract
Iron-based superconductors display a variety of magnetic phases originating in the competition between electronic, orbital, and spin degrees of freedom. Previous theoretical investigations of the multi-orbital Hubbard model in one-dimension revealed the existence of an orbital-selective Mott phase (OSMP) with block spin order. Recent inelastic neutron scattering (INS) experiments on the BaFe2Se3 ladder compound confirmed the relevance of the block-OSMP. Moreover, the powder INS spectrum revealed an unexpected structure, containing both low-energy acoustic and high-energy optical modes. Here we present the theoretical prediction for the dynamical spin structure factor within a block-OSMP regime using the density-matrix renormalization-group method. In agreement with experiments, we find two dominant features: low-energy dispersive and high-energy dispersionless modes. We argue that the former represents the spin-wave-like dynamics of the block ferromagnetic islands, while the latter is attributed to a novel type of local on-site spin excitations controlled by the Hund coupling. Exploring the orbital-selective Mott phase (OSMP) addresses the central issue of electron correlations in the iron-based superconductors. Here the authors theoretically study the dynamical spin structure factor in the block-OSMP regime and unveil momentum dependent characteristics for different spin excitation modes.
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Gerbi A, Buzio R, Kawale S, Bellingeri E, Martinelli A, Bernini C, Tresca C, Capone M, Profeta G, Ferdeghini C. Atomic-scale distortions and temperature-dependent large pseudogap in thin films of the parent iron-chalcogenide superconductor Fe 1+y Te. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:485002. [PMID: 29120863 DOI: 10.1088/1361-648x/aa9103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We investigate with scanning tunneling microscopy/spectroscopy (STM/STS) and density functional theory (DFT) calculations the surface structures and the electronic properties of Fe1+y Te thin films grown by pulsed laser deposition. Contrary to the regular arrangement of antiferromagnetic nanostripes previously reported on cleaved single-crystal samples, the surface of Fe1+y Te thin films displays a peculiar distribution of spatially inhomogeneous nanostripes. Both STM and DFT calculations show the bias-dependent nature of such features and support the interpretation of spin-polarized tunneling between the FeTe surface and an unintentionally magnetized tip. In addition, the spatial inhomogeneity is interpreted as a purely electronic effect related to changes in hybridization and Fe-Fe bond length driven by local variations in the concentration of excess interstitial Fe cations. Unexpectedly, the surface density of states measured by STS strongly evolves with temperature in close proximity to the antiferromagnetic-paramagnetic first-order transition, and reveals a large pseudogap of 180-250 meV at about 50-65 K. We believe that in this temperature range a phase transition takes place, and the system orders and locks into particular combinations of orbitals and spins because of the interplay between excess interstitial magnetic Fe and strongly correlated d-electrons.
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Affiliation(s)
- Andrea Gerbi
- CNR-SPIN Institute for Superconductors, Innovative Materials and Devices, Corso Perrone 24, 16152 Genova, Italy
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Chi S, Uwatoko Y, Cao H, Hirata Y, Hashizume K, Aoyama T, Ohgushi K. Magnetic Precursor of the Pressure-Induced Superconductivity in Fe-Ladder Compounds. PHYSICAL REVIEW LETTERS 2016; 117:047003. [PMID: 27494496 DOI: 10.1103/physrevlett.117.047003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Indexed: 06/06/2023]
Abstract
The pressure effects on the antiferromagentic orders in iron-based ladder compounds CsFe_{2}Se_{3} and BaFe_{2}S_{3} have been studied using neutron diffraction. With identical crystal structure and similar magnetic structures, the two compounds exhibit highly contrasting magnetic behaviors under moderate external pressures. In CsFe_{2}Se_{3} the ladders are brought much closer to each other by pressure, but the stripe-type magnetic order shows no observable change. In contrast, the stripe order in BaFe_{2}S_{3} undergoes a quantum phase transition where an abrupt increase of Néel temperature by more than 50% occurs at about 1 GPa, accompanied by a jump in the ordered moment. With its spin structure unchanged, BaFe_{2}S_{3} enters an enhanced magnetic phase that bears the characteristics of an orbital selective Mott phase, which is the true neighbor of superconductivity emerging at higher pressures.
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Affiliation(s)
- Songxue Chi
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yoshiya Uwatoko
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Huibo Cao
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yasuyuki Hirata
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581, Japan
| | - Kazuki Hashizume
- Department of Physics, Graduate School of Science, Tohoku University, 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Takuya Aoyama
- Department of Physics, Graduate School of Science, Tohoku University, 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Kenya Ohgushi
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581, Japan
- Department of Physics, Graduate School of Science, Tohoku University, 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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10
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Liu G, Kaushal N, Li S, Bishop CB, Wang Y, Johnston S, Alvarez G, Moreo A, Dagotto E. Orbital-selective Mott phases of a one-dimensional three-orbital Hubbard model studied using computational techniques. Phys Rev E 2016; 93:063313. [PMID: 27415393 DOI: 10.1103/physreve.93.063313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Indexed: 06/06/2023]
Abstract
A recently introduced one-dimensional three-orbital Hubbard model displays orbital-selective Mott phases with exotic spin arrangements such as spin block states [J. Rincón et al., Phys. Rev. Lett. 112, 106405 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.106405]. In this publication we show that the constrained-path quantum Monte Carlo (CPQMC) technique can accurately reproduce the phase diagram of this multiorbital one-dimensional model, paving the way to future CPQMC studies in systems with more challenging geometries, such as ladders and planes. The success of this approach relies on using the Hartree-Fock technique to prepare the trial states needed in CPQMC. We also study a simplified version of the model where the pair-hopping term is neglected and the Hund coupling is restricted to its Ising component. The corresponding phase diagrams are shown to be only mildly affected by the absence of these technically difficult-to-implement terms. This is confirmed by additional density matrix renormalization group and determinant quantum Monte Carlo calculations carried out for the same simplified model, with the latter displaying only mild fermion sign problems. We conclude that these methods are able to capture quantitatively the rich physics of the several orbital-selective Mott phases (OSMP) displayed by this model, thus enabling computational studies of the OSMP regime in higher dimensions, beyond static or dynamic mean-field approximations.
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Affiliation(s)
- Guangkun Liu
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Nitin Kaushal
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Shaozhi Li
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Christopher B Bishop
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yan Wang
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Steve Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Gonzalo Alvarez
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Adriana Moreo
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Elbio Dagotto
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Mourigal M, Wu S, Stone MB, Neilson JR, Caron JM, McQueen TM, Broholm CL. Block Magnetic Excitations in the Orbitally Selective Mott Insulator BaFe_{2}Se_{3}. PHYSICAL REVIEW LETTERS 2015; 115:047401. [PMID: 26252707 DOI: 10.1103/physrevlett.115.047401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Indexed: 06/04/2023]
Abstract
Iron pnictides and selenides display a variety of unusual magnetic phases originating from the interplay between electronic, orbital, and lattice degrees of freedom. Using powder inelastic neutron scattering on the two-leg ladder BaFe_{2}Se_{3}, we fully characterize the static and dynamic spin correlations associated with the Fe_{4} block state, an exotic magnetic ground state observed in this low-dimensional magnet and in Rb_{0.89}Fe_{1.58}Se_{2}. All the magnetic excitations of the Fe_{4} block state predicted by an effective Heisenberg model with localized spins are observed below 300 meV and quantitatively reproduced. However, the data only account for 16(3)μ_{B}^{2} per Fe^{2+}, approximatively 2/3 of the total spectral weight expected for localized S=2 moments. Our results highlight how orbital degrees of freedom in iron-based magnets can conspire to stabilize an exotic magnetic state.
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Affiliation(s)
- M Mourigal
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Shan Wu
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - M B Stone
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J R Neilson
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J M Caron
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - T M McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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