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Srivastava MK, Qiu XS, Chin YY, Hsieh SH, Shao YC, Liang YH, Lai CH, Du CH, Wang HT, Chiou JW, Lai YC, Tsai HM, Pao CW, Lin HJ, Lee JF, Asokan K, Pong WF. The effect of orbital-lattice coupling on the electrical resistivity of YBaCuFeO 5 investigated by X-ray absorption. Sci Rep 2019; 9:18586. [PMID: 31819082 PMCID: PMC6901513 DOI: 10.1038/s41598-019-54772-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 11/14/2019] [Indexed: 11/25/2022] Open
Abstract
Temperature-dependent X-ray absorption near-edge structures, X-ray linear dichroism (XLD) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques were used to investigate the valence state, preferred orbital and local atomic structure that significantly affect the electrical and magnetic properties of a single crystal of YBaCuFeO5 (YBCFO). An onset of increase of resistivity at ~180 K, followed by a rapid increase at/below 125 K, is observed. An antiferromagnetic (AFM)-like transition is close to the temperature at which the resistivity starts to increase in the ab-plane and is also observed with strong anisotropy between the ab-plane and the c-axis. The XLD spectra at the Fe L3,2-edge revealed a change in Fe 3d eg holes from the preferential [Formula: see text] orbital at high temperature (300-150 K) to the [Formula: see text] orbital at/below 125 K. The analysis of the Fe K-edge EXAFS data of YBCFO further revealed an unusual increase in the Debye-Waller factor of the nearest-neighbor Fe-O bond length at/below 125 K, suggesting phonon-softening behavior, resulting in the breaking of lattice symmetry, particularly in the ab-plane of Fe-related square pyramids. These findings demonstrate a close correlation between electrical resistivity and coupling of the preferred Fe 3d orbital with lattice distortion of a single crystal of YBCFO.
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Affiliation(s)
- M K Srivastava
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
- Department of Physics, Banasthali Vidyapith, Rajasthan, 304022, India
| | - X-S Qiu
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - Y Y Chin
- Department of Physics, National Chung Cheng University, Chiayi, 621, Taiwan
| | - S H Hsieh
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - Y C Shao
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - Y-H Liang
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - C-H Lai
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - C H Du
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - H T Wang
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
- Department of Physics, National Tsinghua University, Hsinchu, 300, Taiwan
| | - J W Chiou
- Department of Applied Physics, National University of Kaohsiung, Kaohsiung, 811, Taiwan
| | - Y C Lai
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - H M Tsai
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - C W Pao
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - H J Lin
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - J F Lee
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - K Asokan
- Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi, 110 067, India
| | - W F Pong
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan.
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Rangkuti CN, Cahaya AB, Azhar A, Majidi MA, Rusydi A. Manifestation of charge/orbital order and charge transfer in temperature-dependent optical conductivity of single-layered Pr 0.5Ca 1.5MnO 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:365601. [PMID: 31121564 DOI: 10.1088/1361-648x/ab2433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Half-doped single-layered manganite, [Formula: see text] has shown a charge/orbital order of the e g electrons and CE-type spin order of the t 2g electrons of the Mn ions. A previous experimental study on that system, supported by a simple modelling, has suggested that the charge/orbital ordering play an important role in governing the temperature dependence of optical conductivity of a broad peak around 0.7-0.8 eV. In addition, another peak around 3.5 eV, which is less sensitive to temperature, has been attributed to the charge transfer from O-p to Mn-e g orbitals. Nevertheless, the theoretical explanation was incomplete as the role of O-p orbitals was not considered in the model. In this paper, we propose to improve the model by incorporating both Mn-e g and O-p orbitals. We assume the existence of charge/orbital ordering and investigate how this ordering as well as the charge-transfer phenomenon control the temperature dependence of the optical conductivity. Our results reveal the charge/orbital-ordering peak in the region 0.7-1.2 eV, which is blue-shifted with decreasing temperature, and the charge-transfer peak around 3.5 eV, which is less sensitive to temperature. The capability of our model to capture the general profile and temperature dependence of the optical conductivity suggests the validity of our theory.
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Affiliation(s)
- Choirun Nisaa Rangkuti
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424, Indonesia
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Anisotropy in the magnetic interaction and lattice-orbital coupling of single crystal Ni 3TeO 6. Sci Rep 2018; 8:15779. [PMID: 30361523 PMCID: PMC6202349 DOI: 10.1038/s41598-018-33976-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/09/2018] [Indexed: 11/12/2022] Open
Abstract
This investigation reports on anisotropy in the magnetic interaction, lattice-orbital coupling and degree of phonon softening in single crystal Ni3TeO6 (NTO) using temperature- and polarization-dependent X-ray absorption spectroscopic techniques. The magnetic field-cooled and zero-field-cooled measurements and temperature-dependent Ni L3,2-edge X-ray magnetic circular dichroism spectra of NTO reveal a weak Ni-Ni ferromagnetic interaction close to ~60 K (TSO: temperature of the onset of spin ordering) with a net alignment of Ni spins (the uncompensated components of the Ni moments) along the crystallographic c-axis, which is absent from the ab-plane. Below the Néel temperature, TN~ 52 K, NTO is stable in the antiferromagnetic state with its spin axis parallel to the c-axis. The Ni L3,2-edge X-ray linear dichroism results indicate that above TSO, the Ni 3d eg electrons preferentially occupy the out-of-plane 3d3z2−r2 orbitals and switch to the in-plane 3dx2−y2 orbitals below TSO. The inherent distortion of the NiO6 octahedra and anisotropic nearest-neighbor Ni-O bond lengths between the c-axis and the ab-plane of NTO, followed by anomalous Debye-Waller factors and orbital-lattice in conjunction with spin-phonon couplings, stabilize the occupied out-of-plane (3d3z2−r2) and in-plane (3dx2−y2) Ni eg orbitals above and below TSO, respectively.
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Anisotropy in the thermal hysteresis of resistivity and charge density wave nature of single crystal SrFeO 3-δ: X-ray absorption and photoemission studies. Sci Rep 2017; 7:161. [PMID: 28279015 PMCID: PMC5428035 DOI: 10.1038/s41598-017-00247-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 02/15/2017] [Indexed: 11/08/2022] Open
Abstract
The local electronic and atomic structures of the high-quality single crystal of SrFeO3-δ (δ~0.19) were studied using temperature-dependent x-ray absorption and valence-band photoemission spectroscopy (VB-PES) to investigate the origin of anisotropic resistivity in the ab-plane and along the c-axis close to the region of thermal hysteresis (near temperature for susceptibility maximum, Tm~78 K). All experiments herein were conducted during warming and cooling processes. The Fe L3,2-edge X-ray linear dichroism results show that during cooling from room temperature to below the transition temperature, the unoccupied Fe 3d eg states remain in persistently out-of-plane 3d3z2-r2 orbitals. In contrast, in the warming process below the transition temperature, they change from 3d3z2-r2 to in-plane 3dx2-y2 orbitals. The nearest-neighbor (NN) Fe-O bond lengths also exhibit anisotropic behavior in the ab-plane and along the c-axis below Tm. The anisotropic NN Fe-O bond lengths and Debye-Waller factors stabilize the in-plane Fe 3dx2-y2 and out-of-plane 3d3z2-r2 orbitals during warming and cooling, respectively. Additionally, a VB-PES study further confirms that a relative band gap opens at low temperature in both the ab-plane and along the c-axis, providing the clear evidence of the charge-density-wave nature of SrFeO3-δ (δ~0.19) single crystal.
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Ye F, Chi S, Fernandez-Baca JA, Moreo A, Dagotto E, Lynn JW, Mathieu R, Kaneko Y, Tokura Y, Dai P. Electronic self-organization in the single-layer manganite Pr1-xCa1+xMnO4. PHYSICAL REVIEW LETTERS 2009; 103:167202. [PMID: 19905720 DOI: 10.1103/physrevlett.103.167202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Indexed: 05/28/2023]
Abstract
We use neutron scattering to investigate the doping evolution of the magnetic correlations in the single-layer manganite Pr1-xCa1+xMnO4, away from the x=0.5 composition where the CE-type commensurate antiferromagnetic (AF) structure is stable. We find that short-range incommensurate spin correlations develop as the system is electron doped (x<0.5), which coexist with the CE-type AF order. This suggests that electron doping in this system induces an inhomogeneous electronic self-organization, where commensurate AF patches with x=0.5 are separated by electron-rich domain walls with short-range magnetic correlations. This behavior is strikingly different than for the perovskite Pr1-xCaxMnO3, where the long-range CE-type commensurate AF structure is stable over a wide range of electron or hole doping around x=0.5.
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Affiliation(s)
- F Ye
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA.
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