低补偿度n-Hg1-xCdxTe的磁致金属-绝缘体相变和相变后的温度激活输运行为

报道了ｘ＝０．２１４组份、低补偿度（Ｋ《１）ｎ－Ｈｇ_1-xＣｄ_xＴｅ晶体在０．３─３０Ｋ温度范围，０─７Ｔ强磁场下的横向磁阻、电子霍耳迁移率、霍耳系数测量结果，观测到了磁致金属－绝缘体相变和相变后的温度激活输运行为。分析实验数据，提出：低补偿度、组份：ｘ＝０．２附近的ｎ－Ｈｇ_1-xＣｄ_xＴｅ，磁致金属－绝缘体相变（ＭＩＴ）发生的机理是载流子在浅施主杂质态上的磁冻结；发生磁冻结的前提是热冻出（ｔｈｅｒｍａｌ ｆｒｅｅｚｅ 关键词：

MAGNETIC-FIELD-INDUCED METAL-INSULATOR TRANSITION AND THERMALLY ACTIVATED ELECTRONIC TRANSPORT IN LOW COMPENSATED n-Hg1-xCdxTe

Transverse magnet ores istance, electronic mobility and Hall coefficient of low compensated (K《1)n-Hg_1-xCd_xTe(x=0.214) have been measured at low temperatures from 0.3K to 30K and high magnetic field up to 7T. Magnetic-field-induced metal-insulator transition (MIT) has been found in our sample. According to the experimental data, we suggest that the mechanism of the magnetic induced MIT in low copmensated n-Hg_1-xCd_xTe (x is around 0.2) is magnetic freeze-out of carriers to shallow impurity states. Prerequisite condition of the magnetic freeze-out is thermal freeze-out which forces the carriers from conduction band to shallow impurity state at very low temperature. Thermally activated conduction of electrons can be described by the expression Ｒ_H（Ｔ）＝Ｒ_H0expa/kT]. It represents the thermally activated process of electrons bound in impurity state. From activation energy of the conductivity in nonmetallic region, we infer that there are two shallow impurity states in the sample.