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Sohn CH, Kim CH, Sandilands LJ, Hien NTM, Kim SY, Park HJ, Kim KW, Moon SJ, Yamaura J, Hiroi Z, Noh TW. Strong Spin-Phonon Coupling Mediated by Single Ion Anisotropy in the All-In-All-Out Pyrochlore Magnet Cd_{2}Os_{2}O_{7}. Phys Rev Lett 2017; 118:117201. [PMID: 28368646 DOI: 10.1103/physrevlett.118.117201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Indexed: 06/07/2023]
Abstract
Spin-phonon coupling mediated by single ion anisotropy was investigated using optical spectroscopy and first-principles calculations in the all-in-all-out pyrochlore magnet Cd_{2}Os_{2}O_{7}. Clear anomalies were observed in both the phonon frequencies and linewidths at the magnetic ordering temperature. The renormalization of the phonon modes was exceptionally large, signifying the presence of an unconventional magnetoelastic term from large spin-orbit coupling. In addition, the relative phonon frequency shifts show a strong correlation with the modulation of noncubic crystal field by the corresponding lattice distortion. Our observation establishes a new type of spin-phonon coupling through single ion anisotropy, a second-order spin-orbit coupling term, in Cd_{2}Os_{2}O_{7}.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - N T M Hien
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - S Y Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 133-791, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
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Sohn CH, Cho DY, Kuo CT, Sandilands LJ, Qi TF, Cao G, Noh TW. X-ray Absorption Spectroscopy Study of the Effect of Rh doping in Sr2IrO4. Sci Rep 2016; 6:23856. [PMID: 27025538 PMCID: PMC4812298 DOI: 10.1038/srep23856] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/16/2016] [Indexed: 11/16/2022] Open
Abstract
We investigate the effect of Rh doping in Sr2IrO4 using X-ray absorption spectroscopy (XAS). We observed appearance of new electron-addition states with increasing Rh concentration (x in Sr2Ir1-xRhxO4) in accordance with the concept of hole doping. The intensity of the hole-induced state is however weak, suggesting weakness of charge transfer (CT) effect and Mott insulating ground states. Also, Ir Jeff = 1/2 upper Hubbard band shifts to lower energy as x increases up to x = 0.23. Combined with optical spectroscopy, these results suggest a hybridisation-related mechanism, in which Rh doping can weaken the (Ir Jeff = 1/2)-(O 2p) orbital hybridisation in the in-planar Rh-O-Ir bond networks.
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Affiliation(s)
- C. H. Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Deok-Yong Cho
- IPIT & Department of Physics, Chonbuk National University, Jeonju 54896, Korea
| | - C.-T. Kuo
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - L. J. Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - T. F. Qi
- Center for Advanced Materials, Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - G. Cao
- Center for Advanced Materials, Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - T. W. Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
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Sohn CH, Jeong H, Jin H, Kim S, Sandilands LJ, Park HJ, Kim KW, Moon SJ, Cho DY, Yamaura J, Hiroi Z, Noh TW. Optical Spectroscopic Studies of the Metal-Insulator Transition Driven by All-In-All-Out Magnetic Ordering in 5d Pyrochlore Cd(2)Os(2)O(7). Phys Rev Lett 2015; 115:266402. [PMID: 26765010 DOI: 10.1103/physrevlett.115.266402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Indexed: 06/05/2023]
Abstract
We investigated the metal-insulator transition (MIT) driven by all-in-all-out (AIAO) antiferromagnetic ordering in the 5d pyrochlore Cd(2)Os(2)O(7) using optical spectroscopy and first-principles calculations. We showed that the temperature evolution in the band-gap edge and free carrier density were consistent with rigid upward (downward) shifts of electron (hole) bands, similar to the case of Lifshitz transitions. The delicate relationship between the band gap and free carrier density provides experimental evidence for the presence of an AIAO metallic phase, a natural consequence of such MITs. The associated spectral weight change at high energy and first-principles calculations further support the origin of the MIT from the band shift near the Fermi level. Our data consistently support that the MIT induced by AIAO ordering in Cd(2)Os(2)O(7) is not close to a Slater type but instead to a Lifshitz type.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Hogyun Jeong
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Hosub Jin
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Soyeon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - Deok-Yong Cho
- Department of Physics, Chonbuk National University, Jeonju 54896, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
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