Spin dynamics in triangular-lattice antiferromagnets CuCr1−xMgxO2
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
Accepted: 17 January 2011
The electron spin resonance (ESR) spectroscopy was employed to investigate the spin dynamics in triangular-lattice antiferromagnets CuCr1− xMgxO2 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 TN 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 TN. These results indicate that the AFM spin fluctuations are extremely strong in the undoped sample and appear to be suppressed upon Mg doping.
PACS: 76.30.-v – Electron paramagnetic resonance and relaxation / 75.50.Ee – Antiferromagnetics / 75.30.-m – Intrinsic properties of magnetically ordered materials
© EPLA, 2011