Spin dynamics in triangular-lattice antiferromagnets CuCr_1−xMg_xO₂

Author： Li Renwen Qu Zhe Tong Wei Zhang Yuheng

E-ISSN： 1286-4854|93|3|37004-37004

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.93, Iss.3, 2011-02, pp. : 37004-37004

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Abstract

The electron spin resonance (ESR) spectroscopy was employed to investigate the spin dynamics in triangular-lattice antiferromagnets CuCr_{1− x}Mg_xO₂ with x = 0 and 0.02. All spectra can be well fitted by a single Lorentzian lineshape. The analysis of the g-factor, the linewidth ΔH, and the ESR intensity I as a function of temperature suggests the development of significant antiferromagnetic (AFM) spin fluctuations at temperature well above T_N in both samples. However, the evolution of the AFM spin fluctuations is different for each sample. For the undoped sample the ESR intensity I is almost temperature independent between ~100 K and 50 K and then drops rapidly below 50 K. But for x = 0.02, the I monotonously increases with cooling and reduces rapidly only below T_N. These results indicate that the AFM spin fluctuations are extremely strong in the undoped sample and appear to be suppressed upon Mg doping.