Colossal Magnetoresistance and Unusual Resistivity Behaviors in Magnetic Semiconductors: Mn3Si2Te6 as a Case Study

Colossal magnetoresistance (CMR) is typically observed in manganites and magnetic semiconductors, marked by a resistivity peak near the magnetic transition temperature that is significantly suppressed by an applied magnetic field, commonly referred as peak-type CMR. This type of CMR has attracted extensive research efforts over the past decades. However, in some materials such as Mn3Si2Te6, both peak‑type and upturn‑type CMR coexist---the latter characterized by a sharp resistivity upturn at low temperatures that is also strongly suppressed by an external field. Research on the coexistence of these two types of CMR remains relatively unexplored. In our work, we propose a theoretical framework to unravel the mechanisms underlying the above mentioned CMR phenomenon in magnetic semiconductors, and apply it to the ferrimagnetic semiconductor Mn3Si2Te6. The experimentally observed $\rho(B, T)$ behaviors are accurately reproduced, including the upturn-type CMR, peak-type CMR, and movement of $T_c$ (or resistivity peak) with fields. Additionally, the suppression of $T_c$ and resistivity with increasing direct currents, previously attributed to current control of the chiral orbital current (COC) state, is also reproduced within our framework by properly accounting for the Joule heating effects. Our work provides a new perspective for quantitatively calculating and analyzing the unusual resistivity responses to temperature, field and current in magnetic semiconductors.