Critical behavior of the spinel CdCr2S4.

We present our investigation on the critical behavior of the spinel compound CdCr2S4 via the ac susceptibility and dc magnetization measurements. The analysis of ac susceptibility in terms of scaling behavior yields exponent values of δ=5.38±0.01, γ+β=1.77±0.03 and γ=1.44±0.02. Both δ and γ are slightly larger than that predicted by Heisenberg model. Detailed analyses of the inverse of the susceptibility and the electron spin resonance experiment reveal that the existence of correlated magnetic polarons has a key impact on the ferromagnetism of the spinel CdCr2S4. The abnormal critical exponent value of δ of CdCr2S4 may be attributed to the formation of the correlated magnetic polarons and abnormal spin-phonon coupling. [ABSTRACT FROM AUTHOR]