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Liu M, Sternbach AJ, Basov DN. Nanoscale electrodynamics of strongly correlated quantum materials. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:014501. [PMID: 27811387 DOI: 10.1088/0034-4885/80/1/014501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electronic, magnetic, and structural phase inhomogeneities are ubiquitous in strongly correlated quantum materials. The characteristic length scales of the phase inhomogeneities can range from atomic to mesoscopic, depending on their microscopic origins as well as various sample dependent factors. Therefore, progress with the understanding of correlated phenomena critically depends on the experimental techniques suitable to provide appropriate spatial resolution. This requirement is difficult to meet for some of the most informative methods in condensed matter physics, including infrared and optical spectroscopy. Yet, recent developments in near-field optics and imaging enabled a detailed characterization of the electromagnetic response with a spatial resolution down to 10 nm. Thus it is now feasible to exploit at the nanoscale well-established capabilities of optical methods for characterization of electronic processes and lattice dynamics in diverse classes of correlated quantum systems. This review offers a concise description of the state-of-the-art near-field techniques applied to prototypical correlated quantum materials. We also discuss complementary microscopic and spectroscopic methods which reveal important mesoscopic dynamics of quantum materials at different energy scales.
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Affiliation(s)
- Mengkun Liu
- Department of Physics, Stony Brook University, Stony Brook, NY 11794, USA
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Sugai S, Nohara J, Shiozaki R, Muroi T, Takayanagi Y, Hayamizu N, Takenaka K, Okazaki K. Correlation between Raman sum and optical conductivity sum in La(2-x)Sr(x)CuO4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:415701. [PMID: 24055839 DOI: 10.1088/0953-8984/25/41/415701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In a strongly correlated electron system, the single-particle spectral function changes into a coherent peak and incoherent humps which extend over 1 eV. The incoherent parts lose the symmetry and k dependence, so that the Raman spectra with different symmetries become identical and they are expressed by the optical conductivity. We found that the B1g and B2g spectra in La(2-x)Sr(x)CuO4 become identical above 2000 cm(-1) in the underdoped phase, if Fleury-Loudon type B1g two-magnon scattering is removed. The first Raman susceptibility moment correlates with the generalized optical conductivity moment. The good correlation arises from the incoherent states of a hump from 1000 to 4000 cm(-1). The hump is the only structure of the incoherent electronic states in the mid-infrared absorption spectra below 1.4 eV at low carrier densities. The energy is twice the separated dispersion segments of the spin wave in the k(perpendicular) stripe direction. The incoherent state is formed by the magnetic excitations created by the hole hopping in the antiferromagnetic spin stripes in the real space picture.
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Affiliation(s)
- S Sugai
- Department of Physics, Arts and Science, Petroleum Institute, PO Box 2533, Abu Dhabi, UAE. Department of Physics, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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Shi X, Logvenov G, Bollinger AT, Božović I, Panagopoulos C, Popović D. Emergence of superconductivity from the dynamically heterogeneous insulating state in La(2-x)Sr(x)CuO4. NATURE MATERIALS 2013; 12:47-51. [PMID: 23160270 DOI: 10.1038/nmat3487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 10/09/2012] [Indexed: 06/01/2023]
Abstract
A central issue for copper oxides is the nature of the insulating ground state at low carrier densities and the emergence of high-temperature superconductivity from that state with doping. Even though this superconductor-insulator transition (SIT) is a zero-temperature transition, measurements are not usually carried out at low temperatures. Here we use magnetoresistance to probe both the insulating state at very low temperatures and the presence of superconducting fluctuations in La(2-x)Sr(x)CuO(4) films, for doping levels that range from the insulator to the superconductor (x = 0.03-0.08). We observe that the charge glass behaviour, characteristic of the insulating state, is suppressed with doping, but it coexists with superconducting fluctuations that emerge already on the insulating side of the SIT. The unexpected quenching of the superconducting fluctuations by the competing charge order at low temperatures provides a new perspective on the mechanism for the SIT.
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Affiliation(s)
- Xiaoyan Shi
- National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
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Silva Neto MB. Anisotropy of acceptor states in lightly doped cuprate superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:365601. [PMID: 21852728 DOI: 10.1088/0953-8984/23/36/365601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigate the role of short wavelength antiferromagnetic correlations in the spatial structure of acceptor states doped into a two-dimensional Mott-Hubbard antiferromagnetic insulator. We extend the traditional effective mass approximation, by using the Green's function formalism and its spectral representation, and we show that when the electronic scattering at the ordering wavevector Q = (π,π) is strong enough to produce a momentum dependent scattering rate, Γ(k), the corresponding acceptor state envelope wavefunction becomes spatially anisotropic. Finally, we discuss the connection between our results and photoemission spectra in lightly doped La(2-x)Sr(x)CuO(4).
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Affiliation(s)
- M B Silva Neto
- Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Silva Neto MB, Blumberg G, Gozar A, Komiya S, Ando Y. Anisotropies in the optical ac and dc conductivities in lightly doped La(2 - x)Sr(x)CuO4: the role of deep and shallow acceptor states. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:215602. [PMID: 21558605 DOI: 10.1088/0953-8984/23/21/215602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigate the origin of the optical ac and dc conductivity anisotropies observed in the low temperature orthorhombic phase of lightly doped, untwinned La(2 - x)Sr(x)NiO(4) single crystals. We show that these anisotropies can be naturally ascribed to the emergence of two odd parity, rotational-symmetry-broken, localized impurity acceptor states, one deeper and one shallower, resulting from the trapping of doped holes by the Coulomb potential provided by the Sr ions. These two lowest-energy, p-wave-like states are split by orthorhombicity and are partially filled with holes. This leaves a unique imprint in the optical ac conductivity, which shows two distinct far-infrared continuum absorption energies corresponding to the photoionization of the deep and shallow acceptor states. Furthermore, we argue that the existence of two independent and orthogonal channels for hopping conductivity, directly associated with the two orthorhombic directions, also quantitatively explains the observed low temperature anisotropies in the dc conductivity.
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Affiliation(s)
- M B Silva Neto
- Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Jiang HM, Chen CP, Li JX. Spectral and optical properties in the antiphase stripe phase of the cuprate superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:375701. [PMID: 21832351 DOI: 10.1088/0953-8984/21/37/375701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigate the superconducting order parameter, the spectral and optical properties in a stripe model with spin-(charge-) domain-derived scattering potential V(s) (V(c)). We show that the charge-domain-derived scattering is less effective than the spin scattering on the suppression of superconductivity. For [Formula: see text], the spectral weight concentrates on the (π,0) antinodal region and a finite energy peak appears in the optical conductivity with the disappearance of the Drude peak. But for V(s)≈V(c), the spectral weight concentrates on the (π/2,π/2) nodal region and a residual Drude peak exists in the optical conductivity without the finite energy peak. These results consistently account for the divergent observations in the ARPES and optical conductivity experiments in several high- T(c) cuprates and suggest that the 'insulating' and 'metallic' properties are intrinsic to the stripe state, depending on the relative strength of the spin- and charge-domain-derived scattering potentials.
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Affiliation(s)
- Hong-Min Jiang
- National Laboratory of Solid State of Microstructure and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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Matsuda M, Fujita M, Wakimoto S, Fernandez-Baca JA, Tranquada JM, Yamada K. Magnetic dispersion of the diagonal incommensurate phase in lightly doped La2-xSrxCuO4. PHYSICAL REVIEW LETTERS 2008; 101:197001. [PMID: 19113297 DOI: 10.1103/physrevlett.101.197001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Indexed: 05/27/2023]
Abstract
We present inelastic neutron scattering experiments on a single-domain crystal of lightly doped La1.96Sr0.04CuO4. We find that the magnetic excitation spectrum in this insulating phase with a diagonal incommensurate spin modulation is remarkably similar to that in the superconducting regime, where the spin modulation is bond parallel. In particular, we find that the dispersion slope at low energy is essentially independent of doping and temperature over a significant range. The energy at which the excitations cross the commensurate antiferromagnetic wave vector increases roughly linearly with doping through the underdoped regime.
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Affiliation(s)
- M Matsuda
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
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Raicević I, Jaroszyński J, Popović D, Panagopoulos C, Sasagawa T. Evidence for charge glasslike behavior in lightly doped La2-xSrxCuO4 at low temperatures. PHYSICAL REVIEW LETTERS 2008; 101:177004. [PMID: 18999777 DOI: 10.1103/physrevlett.101.177004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Indexed: 05/27/2023]
Abstract
A c-axis magnetotransport and resistance noise study in La_(1.97)Sr_(0.03)CuO_(4) reveals clear signatures of glassiness, such as hysteresis, memory, and slow, correlated dynamics, but only at temperatures (T) well below the spin glass transition temperature T_(sg). The results strongly suggest the emergence of charge glassiness, or dynamic charge ordering, as a result of Coulomb interactions.
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Affiliation(s)
- I Raicević
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
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Kitano H, Ohashi T, Maeda A. Broadband method for precise microwave spectroscopy of superconducting thin films near the critical temperature. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:074701. [PMID: 18681723 DOI: 10.1063/1.2954957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We present a high-resolution microwave spectrometer to measure the frequency- dependent complex conductivity of a superconducting thin film near the critical temperature. The instrument is based on a broadband measurement of the complex reflection coefficient, S 11, of a coaxial transmission line, which is terminated to a thin film sample with the electrodes in a Corbino disk shape. In the vicinity of the critical temperature, the standard calibration technique using three known standards fails to extract the strong frequency dependence of the complex conductivity induced by the superconducting fluctuations. This is because a small unexpected difference between the phase parts of S 11 for a short and load standards gives rise to a large error in the detailed frequency dependence of the complex conductivity near the superconducting transition. We demonstrate that a new calibration procedure using the normal-state conductivity of a sample as a load standard resolves this difficulty. The high quality performance of this spectrometer, which covers the frequency range between 0.1 and 10 GHz, the temperature range down to 10 K, and the magnetic field range up to 1 T, is illustrated by the experimental results on several thin films of both conventional and high temperature superconductors.
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Affiliation(s)
- Haruhisa Kitano
- Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa, Japan.
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Komiya S, Chen HD, Zhang SC, Ando Y. Magic doping fractions for high-temperature superconductors. PHYSICAL REVIEW LETTERS 2005; 94:207004. [PMID: 16090276 DOI: 10.1103/physrevlett.94.207004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Indexed: 05/03/2023]
Abstract
We report hole-doping dependence of the in-plane resistivity rho(ab) in a cuprate superconductor La(2-x)Sr(x)CuO4, carefully examined using a series of high-quality single crystals. Our detailed measurements find a tendency towards charge ordering at particular rational hole-doping fractions of 1/16, 3/32, 1/8, and 3/16. This observation appears to suggest a specific form of charge order and is most consistent with the recent theoretical prediction of the checkerboard-type ordering of the Cooper pairs at rational doping fractions x = (2m+1)/2n, with integers m and n.
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Affiliation(s)
- Seiki Komiya
- Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan
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