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Rusydi A, Goos A, Binder S, Eich A, Botril K, Abbamonte P, Yu X, Breese MBH, Eisaki H, Fujimaki Y, Uchida S, Guerassimova N, Treusch R, Feldhaus J, Reininger R, Klein MV, Rübhausen M. Electronic screening-enhanced hole pairing in two-leg spin ladders studied by high-resolution resonant inelastic x-ray scattering at Cu M edges. PHYSICAL REVIEW LETTERS 2014; 113:067001. [PMID: 25148343 DOI: 10.1103/physrevlett.113.067001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 05/23/2023]
Abstract
We study the electronic screening mechanisms of the effective Coulomb on-site repulsion in hole-doped Sr(14)Cu(24)O(41) compared to undoped La(6)Ca(8)Cu(24)O(41) using polarization dependent high-resolution resonant inelastic x-ray scattering at Cu M edges. By measuring the energy of the effective Coulomb on-site repulsion and the spin excitations, we estimate superexchange and hopping matrix element energies along rungs and legs, respectively. Interestingly, hole doping locally screens the Coulomb on-site repulsion reducing it by as much as 25%. We suggest that the increased ratio of the electronic kinetic to the electronic correlation energy contributes to the local superexchange mediated pairing between holes.
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Affiliation(s)
- A Rusydi
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany and NUSSNI-NanoCore, Department of Physics, National University of Singapore, Singapore 117542, Singapore and Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - A Goos
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany
| | - S Binder
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany
| | - A Eich
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany
| | - K Botril
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany
| | - P Abbamonte
- Physics Department and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - X Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - M B H Breese
- NUSSNI-NanoCore, Department of Physics, National University of Singapore, Singapore 117542, Singapore and Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - H Eisaki
- Nanoelectronics Research Institute, AIST, 1-1-1 Central 2, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Y Fujimaki
- Department of Superconductivity, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
| | - S Uchida
- Department of Superconductivity, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
| | - N Guerassimova
- Photon Science, DESY, Notkestraße 85, D-22607 Hamburg, Germany
| | - R Treusch
- Photon Science, DESY, Notkestraße 85, D-22607 Hamburg, Germany
| | - J Feldhaus
- Photon Science, DESY, Notkestraße 85, D-22607 Hamburg, Germany
| | - R Reininger
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M V Klein
- Physics Department and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - M Rübhausen
- Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany and Center for Free Electron Laser Science (CFEL), Notkestraße 85, D-22607 Hamburg, Germany and NUSSNI-NanoCore, Department of Physics, National University of Singapore, Singapore 117542, Singapore
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2
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Choi KY, Hwang JW, Lemmens P, Wulferding D, Shu GJ, Chou FC. Evidence for dimer crystal melting in the frustrated spin-ladder system BiCu2PO6. PHYSICAL REVIEW LETTERS 2013; 110:117204. [PMID: 25166571 DOI: 10.1103/physrevlett.110.117204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/19/2013] [Indexed: 06/03/2023]
Abstract
In the spin ladder compound BiCu(2)PO(6), there exists a decisive dynamics of spin excitations that we classify and characterize using inelastic light scattering. We observe an interladder singlet bound mode at 24 cm(-1) and two intraladder bound states at 62 and 108 cm(-1) in the leg (bb) and the rung (cc) polarization as well as a broad triplon continuum extending from 36 cm(-1) to 700 cm(-1). Though isolated spin ladder physics can roughly account for the observed excitations at high energies, frustration and interladder interactions need to be considered to fully describe the spectral distribution and scattering selection rules at low and intermediate energies. In addition, we attribute the rich spectrum of singlet bound modes to a melting of a dimer crystal. Our study provides evidence for a Z(2) quantum phase transition from a dimer to a resonating valence bond state driven by singlet fluctuations.
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Affiliation(s)
- K-Y Choi
- Department of Physics, Chung-Ang University, 221 Huksuk-Dong, Seoul 156-756, Republic of Korea
| | - J W Hwang
- Department of Physics, Chung-Ang University, 221 Huksuk-Dong, Seoul 156-756, Republic of Korea
| | - P Lemmens
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
| | - D Wulferding
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
| | - G J Shu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - F C Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
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Lekin K, Wong JWL, Winter SM, Mailman A, Dube PA, Oakley RT. Bisdithiazolyl Radical Spin Ladders. Inorg Chem 2013; 52:2188-98. [DOI: 10.1021/ic302658c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kristina Lekin
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1,
Canada
| | - Joanne W. L. Wong
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1,
Canada
| | - Stephen M. Winter
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1,
Canada
| | - Aaron Mailman
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1,
Canada
| | - Paul A. Dube
- Brockhouse Institute
for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Richard T. Oakley
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1,
Canada
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Rusydi A, Ku W, Schulz B, Rauer R, Mahns I, Qi D, Gao X, Wee ATS, Abbamonte P, Eisaki H, Fujimaki Y, Uchida S, Rübhausen M. Experimental observation of the crystallization of a paired holon state. PHYSICAL REVIEW LETTERS 2010; 105:026402. [PMID: 20867721 DOI: 10.1103/physrevlett.105.026402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2008] [Revised: 11/14/2009] [Indexed: 05/29/2023]
Abstract
An excitation at 201 meV is observed in the doped-hole ladder cuprate Sr14Cu24O41, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the rungs. The excitation is of charge nature, with a temperature independent excitation energy, and can be understood via an intraladder pair-breaking process. The intensity tracks closely the order parameter of the charge density wave in the ladder CDW(L), but persists above its transition temperature T(CDW(L)), indicating a strong local pairing above the T(CDW(L)). The 201 meV excitation vanishes in La6Ca8Cu24O(41+δ), and La5Ca9Cu24O41 which are samples with no holes in the ladders. Our results suggest that the doped holes in the ladder are composite bosons consisting of paired holons that order below T(CDW).
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Affiliation(s)
- A Rusydi
- NanoCore, Department of Physics, Faculty of Science, National University of Singapore, 117542, Singapore.
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Schlappa J, Schmitt T, Vernay F, Strocov VN, Ilakovac V, Thielemann B, Rønnow HM, Vanishri S, Piazzalunga A, Wang X, Braicovich L, Ghiringhelli G, Marin C, Mesot J, Delley B, Patthey L. Collective magnetic excitations in the spin ladder Sr14Cu24O41 measured using high-resolution resonant inelastic x-ray scattering. PHYSICAL REVIEW LETTERS 2009; 103:047401. [PMID: 19659397 DOI: 10.1103/physrevlett.103.047401] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Indexed: 05/28/2023]
Abstract
We investigate magnetic excitations in the spin-ladder compound Sr_{14}Cu_{24}O_{41} using high-resolution Cu L_{3} edge resonant inelastic x-ray scattering (RIXS). Our findings demonstrate that RIXS couples to two-triplon collective excitations. In contrast to inelastic neutron scattering, the RIXS cross section changes only moderately over the entire Brillouin zone, revealing high sensitivity also at small momentum transfers, allowing determination of the two-triplon energy gap as 100 +/- 30 meV. Our results are backed by calculations within an effective Hubbard model for a finite-size cluster, and confirm that optical selection rules are obeyed for excitations from this spherically symmetric quantum spin-liquid ground state.
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Affiliation(s)
- J Schlappa
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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Gozar A, Blumberg G, Littlewood PB, Dennis BS, Motoyama N, Eisaki H, Uchida S. Collective density-wave excitations in two-leg Sr14-xCaxCu24O41 ladders. PHYSICAL REVIEW LETTERS 2003; 91:087401. [PMID: 14525276 DOI: 10.1103/physrevlett.91.087401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2002] [Indexed: 05/24/2023]
Abstract
Raman measurements in the 1.5-20 cm(-1) energy range were performed on single crystals of Sr14-xCaxCu24O41. A quasielastic scattering peak (QEP) which softens with cooling is observed only in the polarization parallel to the ladder direction for samples with x=0, 8, and 12. The QEP is a Raman fingerprint of pinned collective density wave excitations screened by uncondensed carriers in the ladder structures. Our results suggest that transport in metallic samples, which is similar to transport in underdoped high-T(c) cuprates, is driven by a collective electronic response.
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Affiliation(s)
- A Gozar
- Lucent Technologies, Bell Laboratories, Murray Hill, New Jersey 07974, USA
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Vuletić T, Korin-Hamzić B, Tomić S, Gorshunov B, Haas P, Rõõm T, Dressel M, Akimitsu J, Sasaki T, Nagata T. Suppression of the charge-density-wave state in Sr14Cu24O41 by calcium doping. PHYSICAL REVIEW LETTERS 2003; 90:257002. [PMID: 12857158 DOI: 10.1103/physrevlett.90.257002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2002] [Indexed: 05/24/2023]
Abstract
The charge response in the spin chain and/or ladder compound Sr14-xCaxCu24O41 is characterized by dc resistivity, low-frequency dielectric spectroscopy and optical spectroscopy. We identify a phase transition below which a charge-density wave (CDW) develops in the ladder arrays. Calcium doping suppresses this phase with the transition temperature decreasing from 210 K for x=0 to 10 K for x=9, and the CDW gap from 130 meV down to 3 meV, respectively. This suppression is due to the worsened nesting originating from the increase of the interladder tight-binding hopping integrals, as well as from disorder introduced at the Sr sites. These results altogether speak in favor of two-dimensional superconductivity under pressure.
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Affiliation(s)
- T Vuletić
- Institut za fiziku, P.O. Box 304, HR-10001 Zagreb, Croatia.
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Schmidt KP, Knetter C, Grüninger M, Uhrig GS. Charge-order-induced sharp Raman peak in Sr14Cu24O41. PHYSICAL REVIEW LETTERS 2003; 90:167201. [PMID: 12731999 DOI: 10.1103/physrevlett.90.167201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2002] [Indexed: 05/24/2023]
Abstract
In the two-leg S=1/2 ladders of Sr14Cu24O41, a modulation of the exchange coupling arises from the charge order within the other structural element, the CuO2 chains. In general, breaking transla-tional invariance by modulation causes gaps within the dispersion of elementary excitations. We show that the gap induced by the charge order can drastically change the magnetic Raman spectrum, leading to the sharp peak observed in Sr14Cu24O41. This sharp Raman line gives insight into the charge-order periodicity and hence into the distribution of carriers. The much broader spectrum of La6Ca8Cu24O41 reflects the response of an undoped ladder in the absence of charge order.
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Affiliation(s)
- K P Schmidt
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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Tohyama T, Onodera H, Tsutsui K, Maekawa S. Resonant two-magnon Raman scattering and photoexcited States in two-dimensional mott insulators. PHYSICAL REVIEW LETTERS 2002; 89:257405. [PMID: 12484919 DOI: 10.1103/physrevlett.89.257405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2002] [Indexed: 05/24/2023]
Abstract
We investigate the resonant two-magnon Raman scattering in two-dimensional (2D) Mott insulators by using a half-filled 2D Hubbard model in the strong coupling limit. By performing numerical diagonalization calculations for small clusters, we find that the Raman intensity is enhanced when the incoming photon energy is not near the optical absorption edge but well above it, being consistent with experimental data. The absence of resonance near the gap edge is associated with the presence of background spins, while photoexcited states for resonance are found to be characterized by the charge degree of freedom. The resonance mechanism is different from those proposed previously.
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Affiliation(s)
- T Tohyama
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
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Blumberg G, Littlewood P, Gozar A, Dennis BS, Motoyama N, Eisaki H, Uchida S. Sliding density wave in Sr14Cu24O41 ladder compounds. Science 2002; 297:584-7. [PMID: 12142532 DOI: 10.1126/science.1070481] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We used transport and Raman scattering measurements to identify the insulating state of self-doped spin (1/2) two-leg ladders of Sr14Cu24O41 as a weakly pinned, sliding density wave with nonlinear conductivity and a giant dielectric response that persists to remarkably high temperatures.
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Affiliation(s)
- G Blumberg
- Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA.
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