Magnetoresistive (MR) read elements and associated methods of fabrication are disclosed. A free layer and/or a pinned layer of an MR read element are formed from a magnetic material such as Co2−x−yMn1+xAl1+y, Co2−x−yMn1+xSi1+y, Co2−x−yMn1+xGe1+y, and Co2−x−yFe1+xSi1+y, where x and y are selected to create an off-stoichiometric alloy having a crystalline structure that is chemically disordered. The chemically disordered magnetic material has a lower spin-polarization than a Heusler alloy, but still exhibits acceptable GMR amplitudes and low spin-torque noise.