An electron paramagnetic resonance study of n-type Zn_(1-x)Mn_xO: A diluted magnetic semiconductor

摘要

We present the results of an electron paramagnetic resonance study of homogeneous single phase Zn_(1-x)Mn_xO thin films with Mn concentrations varying between x = 0.07 and x = 0.34. Our results show antiferromagnetic (AF) coupling in the entire concentration range with an effective exchange integral of J/k_B = -21.8 K for x ≤ 0.16 much stronger than in the CdMn(S,Se,Te) series. We observe deviations from the Curie-Weiss behavior for concentrations above x = 0.16 and show this to be a "universal" behavior of Ⅱ-Ⅵ diluted magnetic semiconductors. Our results demonstrate that AF interactions are dominating in n-type Zn_(1-x)Mn_xO (x > 0.07) with a carrier concentration of 10~(18) cm~(-3) contrary to previous claims. These AF interactions are responsible for high spin freezing temperatures and absence of magnetic long range order.