Spin dynamics in triangular-lattice antiferromagnets CuCr_1−xMg_xO₂

¹ High Magnetic Field Laboratory, Chinese Academy of Sciences - Hefei 230031, China
² Department of Physics and Electronic Engineering, Hefei Normal University - Hefei 230061, China
³ High Magnetic Field Laboratory, University of Science and Technology of China - Hefei 230026, China

^a zhequ@hmfl.ac.cn

Received: 5 September 2010
Accepted: 17 January 2011

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.