Spectral Properties of Magnetic Excitations in Cuprate Two-Leg Ladder Systems

Schmidt, K. P.; Uhrig, Götz S.

doi:10.1142/s0217984905009237

Cited by 72 publications

(149 citation statements)

References 90 publications

Supporting

Mentioning

126

Contrasting

Unclassified

Order By: Relevance

“…Symmetry breaking has drastic effects on the observed magnetic excitations in RIXS spectra as discussed in a recent publication [21]. In the present study we find welldefined excitations, which unambiguously match the predicted dispersion for the two-triplon spectrum [22]. Backed by a numerical Hubbard model investigation, we thereby confirm that the optical selection rules are obeyed for quantum ground states with no broken symmetry.…”

supporting

confidence: 90%

“…¼ 0:35 eV, t k ¼ 0:30 eV while the on-site Coulomb repulsion is U ¼ 3:5 eV, corresponding to J ? $ 140 meV, which is close to the experimental value measured with INS or Raman scattering [22,23,31]. According to results of XAS, the concentration of holes in the ladder system is smaller than 10% [32].…”

supporting

confidence: 80%

“…3(a) to the spectral-density calculations for multitriplon contributions by Schmidt and Uhrig [22], reveals that the dominating magnetic mode observed in our Cu L 3 RIXS data matches very closely the lower boundary of the two-triplon continuum (solid black line), which disperses in complete antiphase with the single-triplon excitation (dashed red line). We therefore unambiguously assign the magnetic excitation in the RIXS spectra to the two-triplon channel.…”

supporting

confidence: 66%

“…Backed by a numerical Hubbard model investigation, we thereby confirm that the optical selection rules are obeyed for quantum ground states with no broken symmetry. While the INS cross section is inherently small around the Brillouin zone (BZ) center (small momentum transfers) [22,23], the observed RIXS signal is found to be intense all over the BZ, allowing us to determine directly the twotriplon energy gap in Sr 14 Cu 24 O 41 at zero momentum transfer as 100 AE 30 meV.RIXS experiments were performed at the Advanced Resonant Spectroscopies (ADRESS) beamline [10], at the Swiss Light Source (SLS), Paul Scherrer Institut, using the Super Advanced X-ray Emission Spectrometer (SAXES) [9]. A flux of 10 13 photons= sec =0:01% bandwidth was focused to a spot size below 6 Â 80 m 2 (vertical Â horizontal).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 4 more Smart Citations

Collective Magnetic Excitations in the Spin LadderSr14Cu24O41Measured Using High-Resolution Resonant Inelastic X-Ray Scattering

et al. 2009

View full text Add to dashboard Cite

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 AE 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. DOI: 10.1103/PhysRevLett.103.047401 PACS numbers: 78.70.En, 71.10.Pm, 75.25.+z, 75.30.Ds Collective excitations in strongly correlated electron materials remain a pivotal challenge in contemporary solid state physics. It is widely debated whether magnetic excitations provide the pairing interaction in the hightemperature and unconventional superconductors [1,2]. From that perspective quantum spin systems attract considerable interest. While most such materials, e.g., the cuprate superconductors, exhibit enormous complexity, the two-leg spin ladder is easier to tract theoretically [3][4][5][6]. It consists of two parallel chains (legs) with a transverse (rung) exchange coupling. This system features a singlet ground state and dispersive triplet excitations (triplons), that both have quantum mechanical origin without any classical counterpart. To date, mainly two techniques have been established as momentum-and energy-resolved probes of the dispersion of collective excitations: angleresolved photoelectron spectroscopy and inelastic neutron scattering (INS) for charge and spin degrees of freedom, respectively [7,8]. Because of the latest instrumental improvements [9,10], the energy scale of magnetic exchange is becoming readily accessible for resonant inelastic x-ray scattering (RIXS) [11][12][13][14], which is promising to give information on both, spin and charge degrees of freedom, and in addition is an element-specific technique. Furthermore, RIXS requires only small sample volumes (<0:1 mm 3 ). Recent RIXS studies were performed on long-range ordered magnets with spin-wave excitations [15][16][17].In this Letter, we report a study of the two-leg quantum spin ladder Sr 14 Cu 24 O 41 [18,19] by means of momentumresolved high-resolution RIXS at the Cu L 3 edge. Given that Cu L 3 scattering experiments have been already shown to contain valuable information about the charge degrees of freedom [20], an outstanding question we would like to address here is: how can RIXS provide information on magnetic excitations from a quantum ground state. In the ladder system of Sr 14 Cu 24 O 41 no symmetry breaking occurs-neither in spin-nor in real-space-in contrast to, e.g., a magnetically ordered state, where both symmetries are broken and the direction of the ordered moments dictates the quantization axi...

show abstract

supporting

confidence: 90%

supporting

confidence: 80%

supporting

confidence: 66%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations