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Magnetic and Raman response properties in La 2 CuO 4

Complex Behavior in Correlated Electron Systems Lorentz Center – 08/01 until 08/19 - 2005. Magnetic and Raman response properties in La 2 CuO 4. Marcello Barbosa da Silva Neto Lara Benfatto Vladimir Juricic Cristiane de Morais Smith. Magnetism in the cuprates. NLSM.

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Magnetic and Raman response properties in La 2 CuO 4

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  1. Complex Behavior in Correlated Electron Systems Lorentz Center – 08/01 until 08/19 - 2005 Magnetic and Raman response properties in La2CuO4 Marcello Barbosa da Silva Neto Lara Benfatto Vladimir Juricic Cristiane de Morais Smith

  2. Magnetism in the cuprates

  3. NLSM

  4. Unusual magnetic susceptibility anisotropies ASHCROFT & MERMIN A. Lavrov et al. PRL (‘01) Unexpected hierarchy of T=0 susceptibilities!

  5. The field induced mode – FIM Appearance of a second magnetic mode for B || b, and ONLY for that orientation, in (RR) configuration Only ONE magnetic mode for the (ab) and (RL) polarization configurations of the light A. Gozar et al., PRL (‘04)

  6. Magnetic anisotropies Tilting + SO coupling

  7. Generalized nonlinear Sigma Model M.B.Silva Neto, L.Benfatto, V.Juricic and C.Morais-Smith, cond-mat/0502588

  8. Magnetic Susceptibility Traditional UNIFORM susceptibility NEW STAGGERED contribution!!!!

  9. Comparison with experiment

  10. The electric-dipole Hamiltonian Elastic scattering

  11. Electric dipole selection rules L=1 L=0 One-magnon energy!

  12. The final electric-dipole Hamiltonian a b c a b c or (ab) channel or (cb) channel M.B.Silva Neto and L.Benfatto, cond-mat/0507103

  13. Raman spectroscopy Backscattering Geometry Electric field ALWAYS parallel to the ab plane!!!

  14. One-magnon Raman Intensity A. Gozar et al., PRL (‘04)

  15. Rotation of spin quantization basis – B||b

  16. The field induced mode - FIM

  17. Hole doping and spirals • Hole doping – dipolar frustration of the AF background • Anisotropies give robustness to the Neel ground state – DM gap vanishes at 2% - V. Juricic et al. in preparation! • Above 2% instability to a spiral phase New periodicity! N.Hasselman et al., PRB (‘04)

  18. Topological defects and transport • Doped holes – cores of topological defects • Dynamics of defects is dissipative – bath of magnons V.Juricic et al., PRL (‘04)

  19. Conclusions • Dzyaloshinskii Moryia interaction accounts for the unusual hierarchy of T=0 susceptibilities and for the anisotropic magnetic response. • It is also responsible for the rotation of the spin quantization basis and appearance of the FIM. • It gives robustness to the Neel ground state and vanishes at 2% where the ground state becomes a spiral.

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