共振受主态在零禁带Hg_(1-x)Mn_xTe磁量子输运中的影响

RESONANT ACCEPTOR INFLUENCED QUANTUM TRANSPORT BEHAVIOR OF ZERO-GAP P-Hg_(1-x)Mn_xTe

在温度为0.3～4.2K,磁场强度为0～7T的范围内对两个不同组份的Hg_(1-x)Mn_xTe(N_A>N_D)样品进行了输运特性的研究.组份x=0.03的样品在弱磁场(B<0.6T)下出现磁阻振荡,用修正的Pidgeon-Brown模型拟合各振荡峰值位置,得到共振受主能级随温度降低而升高,表明受主共振态已形成束缚磁极化子(RABMP).组份x=0.065的样品出现阶段性下降负磁阻行为,理论分析表明这是受主能级钉扎费密能级并在强场(B～1.5T)通过a_v(-1)价带顶引起价带空穴散射增强.两个样品都呈现负磁阻行为,但从磁阻的各向异性及能带分析表明其机理有所不同.

Transport behaviors of two samples of zero-gap P-Hg_(1-x)Mn_xTe (N_A>N_D)have been carefully studied at temperatures 0.3～4.2K and magnetic fields 0～7T. For thesample with x=0.03, Resonant-Acceptor-Bound Magnetic Polarons (RABMP) havebeen found by means of Shubnikov de Haas oscillation. The oscillation peaks have been fit-ted by detailed calculations of the modified Pidgeon-Brown model. The resonant acceptorenergy (which pins the Fermi level) increases with decreasing temperatures, which is the fea-ture of RABMP′s. For the sample with x=0.065, the two-stage negative magnetoresist-ance (NMR) has been found at extremely low temperatures, associated with the Fermi levelpassing through the valence band α_v (-1). All the samples showed NMR, but their mecha-nisms are quite different.