Anomalous dynamical spin susceptibility in the SU(N) Heisenberg spin-glass model and SrCr_{9x}Ga_{12-9x}O_{19}

ALBERTO CAMJAYI; MARCELO JAVIER ROZENBERG

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2004 vol. 69 p. 204041 - 204044

0163-1829

We solve the SU(N) Heisenberg spin-glass model in the limit of large N focusing on the dynamical spin susceptibility. We show that the results for the model at S=3/2, which is appropriate for the SrCr_{9x}Ga_{12-9x }O_{19} compound, have a qualitative behavior in close agreement with neutron-scattering data. Quantum fluctuations produce a significant  transfer of spectral weight to higher frequencies, while thermal fluctuations are responsible for a dramatic change in the low-frequency part of the dynamical spin susceptibility where T becomes comparable to the spin-glass transition temperature.