Theory of Raman scattering in layered cuprate materials

Canali, Carlo M.; Girvin, S. M.

doi:10.1103/physrevb.45.7127

Cited by 136 publications

(203 citation statements)

References 33 publications

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“…Eqs. (5) and (6) yield a two-magnon peak at ∆ω = 2.8J (for S = 1/2), but R(ω) clearly contains no dependence on the incident photon frequency ω i [11,15]. As mentioned earlier, the LF theory is only valid for small ω i .…”

Section: The Formalismmentioning

confidence: 93%

“…It has already been emphasized several times in the literature that the dominant contribution to the magnon-magnon scattering comes from the region near the magnetic Brillouin zone boundary where the antiferromagnetic magnons behave almost as free particles [11,28]. In this situation, the only relevant interaction term has two creation and two annihilation magnon operators:…”

Section: The Formalismmentioning

confidence: 99%

“…1a, where the intermediate magnons (wavy lines) are on the mass shell. The dashed lines in this diagram describe the incident and outgoing photons and the shaded circles represent the full Raman vertices, which include all effects of the final state magnon-magnon interaction [11]. In conventional Raman experiments, one measures the Raman intensity, R, as a function of transferred photon frequency ∆ω = ω i − ω f where ω i and ω f are the incident and outgoing photon frequencies, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Resonant Raman scattering in antiferromagnets

Morr

Chubukov

1997

Phys. Rev. B

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Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-Tc materials. Recent experiments have shown a strong dependence of the Raman signal in B1g geometry on the frequency of the incoming photon. We present an analytical and numerical study of the Raman intensity in the resonant regime. It has been previously argued by one of us (A.Ch) and D. Frenkel that the most relevant contribution to the Raman vertex at resonance is given by the triple resonance diagram. We derive an expression for the Raman intensity in which we simultaneously include the enhancement due to the triple resonance and a final state interaction. We compute the two-magnon peak height (TMPH) as a function of incident frequency and find two maxima at ω (1) res ≈ 2∆ + 3J and ω (2) res ≈ 2∆ + 8J. We argue that the high-frequency maximum is cut only by a quasiparticle damping, while the low-frequency maximum has a finite amplitude even in the absence of damping. We also obtain an evolution of the Raman profile from an asymmetric form around ω (1) res to a symmetric form around ω (2) res . We further show that the TMPH depends on the fermionic quasiparticle damping, the next-nearest neighbor hopping term t ′ and the corrections to the interaction vertex between light and the fermionic current. We discuss our results in the context of recent experiments by Blumberg et al. on Sr2CuO2Cl2 and Y Ba2Cu3O6.1 and Rübhausen et al. on P rBa2Cu3O7 and show that the triple resonance theory yields a qualitative and to some extent also quantitative understanding of the experimental data.

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Section: The Formalismmentioning

confidence: 93%

Section: The Formalismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resonant Raman scattering in antiferromagnets

Morr

Chubukov

1997

Phys. Rev. B

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“…Raman and neutron diffraction experiments evaluate this coupling to be around J N N =130 meV(128±6 meV [1,2],134±5 meV [3,4,5], respectively). Nevertheless, the corresponding simple Heisenberg Hamiltonian does not reproduce entirely the features of the Raman spectrum [6,7,8,9,10,11] and additional effects such as second-neighbor magnetic coupling J N N N and four-spin cyclic exchange have been invoked [12,13,14,15]. While an upper bond for J N N N (|J N N N | ≤9 meV) has been given from Raman experiments [5], the amplitude of the four-spin operator in this kind of compounds is a matter of discussion.…”

Section: Introductionmentioning

confidence: 99%

Proposal of an extendedt−JHamiltonian for high-Tccuprates fromab initiocalculations on embedded clusters

Calzado

Malrieu

2001

Phys. Rev. B

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A series of accurate ab initio calculations on Cu p O q finite clusters, properly embedded on the Madelung potential of the infinite lattice, have been performed in order to determine the local effective interactions in the CuO 2 planes of La 2−x Sr x CuO 4 compounds. The values of the first-neighbor interactions, magnetic coupling (J N N =125 meV) and hopping integral (t N N =-555 meV), have been confirmed. Important additional effects are evidenced, concerning essentially the second-neighbor hopping integral t N N N =+110meV, the displacement of a singlet toward an adjacent colinear hole, h abc SD =-80 meV, a non-negligible hole-hole repulsion V N N − V N N N =0.8 eV and a strong anisotropic effect of the presence of an adjacent hole on the values of the first-neighbor interactions. The dependence of J N N and t N N on the position of neighbor hole(s) has been rationalized from the two-band model and checked from a series of additional ab initio calculations. An extended t-J model Hamiltonian has been proposed on the basis of these results. It is argued that the here-proposed three-body effects may play a role in the charge/spin separation observed in these compounds, that is, in the formation and dynamic of stripes.

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“…We review possible sources of the high-energy spectral weight which were suggested in the past, e.g. quantum fluctuations 26,41,42,43,44,45 , the role of spin-phonon interaction 4, 46,47,48,49,50,51 and the triple resonance 5, 52,53,54 . In case of the cuprate planes no final conclusion concerning the origin of the high-energy weight can be drawn, but in the case of the cuprate ladders the spin-phonon coupling and the triple resonance can be ruled out.…”

Section: Introductionmentioning

confidence: 99%

Raman response of magnetic excitations in cuprate ladders and planes

et al. 2005

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An unified picture for the Raman response of magnetic excitations in cuprate spin-ladder compounds is obtained by comparing calculated two-triplon Raman line-shapes with those of the prototypical compounds SrCu2O3 (Sr123), Sr14Cu24O41 (Sr14), and La6Ca8Cu24O41 (La6Ca8). The theoretical model for the two-leg ladder contains Heisenberg exchange couplings J and J ⊥ plus an additional four-spin interaction Jcyc. Within this model Sr123 and Sr14 can be described by x := J /J ⊥ = 1.5, xcyc := Jcyc/J ⊥ = 0.2, J Sr123 ⊥ = 1130 cm −1 and J Sr14 ⊥ = 1080 cm −1 . The couplings found for La6Ca8 are x = 1.2, xcyc = 0.2, and J La6Ca8 ⊥ = 1130 cm −1 . The unexpected sharp two-triplon peak in the ladder materials compared to the undoped two-dimensional cuprates can be traced back to the anisotropy of the magnetic exchange in rung and leg direction. With the results obtained for the isotropic ladder we calculate the Raman line-shape of a two-dimensional square lattice using a toy model consisting of a vertical and a horizontal ladder. A direct comparison of these results with Raman experiments for the two-dimensional cuprates R2CuO4 (R=La,Nd), Sr2CuO2Cl2, and YBa2Cu3O 6+δ yields a good agreement for the dominating two-triplon peak. We conclude that short range quantum fluctuations are dominating the magnetic Raman response in both, ladders and planes. We discuss possible scenarios responsible for the high-energy spectral weight of the Raman line-shape, i.e. phonons, the triple-resonance and multi-particle contributions.

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Theory of Raman scattering in layered cuprate materials

Cited by 136 publications

References 33 publications

Resonant Raman scattering in antiferromagnets

Resonant Raman scattering in antiferromagnets

Proposal of an extendedt−JHamiltonian for high-Tccuprates fromab initiocalculations on embedded clusters

Raman response of magnetic excitations in cuprate ladders and planes

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