The dichalcogenide Bi₂Te₃ and Bi₂Se₃ crystals belong to the 3D topological insulator family. Doping the crystals with magnetic ions can break the time-reversal symmetry and open an energy gap at surface Dirac points. This provides the opportunity of manipulating the surface transport and observing the anomalous quantum Hall effect. We studied magnetic properties of three single-crystalline BiCr _x Se₃ samples with , 0.03, and 0.06 within a temperature range from 2 to 300 K. The dc magnetization revealed the coexistence of antiferromagnetic and ferromagnetic ordering and paramagnetism. Their significance depends on the chromium content. The ferromagnetic phase transition was suppressed by high enough magnetic field. The antiferromagnetic transition near 80 K did not shift visibly up to 50 kOe. The Curie-Weiss law approximation gave the effective magnetic moment close to , which corresponds to divalent chromium ions. Metamagnetic phenomena were found for crystals with and 0.06.

二硫属化物Bi ₂ Te ₃和Bi ₂ Se ₃晶体属于3D拓扑绝缘体家族。用磁性离子掺杂晶体可以打破时间反转对称性并在表面狄拉克点处打开能隙。这提供了操纵表面传输和观察反常量子霍尔效应的机会。我们研究了三个单晶 Bi Cr _x Se ₃样品的磁性能 在 2 到 300 K 的温度范围内分别为 、0.03 和 0.06。直流磁化显示反铁磁和铁磁有序和顺磁性共存。它们的重要性取决于铬含量。铁磁相变被足够高的磁场抑制。80 K 附近的反铁磁跃迁在高达 50 kOe 时没有明显变化。Curie-Weiss 定律近似给出了接近的有效磁矩，这对应于二价铬离子。对于0.06 和 0.06 的晶体，发现了超磁现象。