Analytical Descriptions of Magnetic Properties and Magnetoresistance in n-Type HgCr₂Se₄^*

We present a detailed investigation of magnetic properties of colossal magnetoresistance material HgCr₂Se₄. While spontaneous magnetization and zero-field magnetic susceptibility are found to follow asymptotic scaling laws for a narrow range of temperatures near the critical point, two methods with connections to the renormalization group theory provide analytical descriptions of the magnetic properties for much wider temperature ranges. Based on this, an analytical formula is obtained for the temperature dependence of the low field magnetoresistance in the paramagnetic phase.