Magnetic Tunnel Junctions

A magnetic tunnel junction comprising:

• a conductive first magnetic electrode comprising magnetic recording material;
• a conductive second magnetic electrode spaced from the first electrode and comprising magnetic reference material;
• a non-magnetic tunnel insulator material between the first and second electrodes;
• and
• the magnetic reference material of the second electrode comprising a synthetic antiferromagnetic construction comprising:
• two spaced magnetic regions one of which is closer to the tunnel insulator material than is the other, the one magnetic region comprising a polarizer region comprising CoxFeyBz where “x” is from 0 to 90, “y” is from 10 to 90, and “z” is from 10 to 50;
• the CoxFeyBz being directly against the tunnel insulator;
• a non-magnetic region comprising an Os-containing material between the two spaced magnetic regions;
• the other magnetic region comprising a magnetic Co-containing material;
• and
• the one magnetic region comprises at least one of elemental-form W, elemental-form Mo, elemental-form Fe, CoaFebWc, CoaFebMoc, and CoaFebTac directly against the CoxFeyBz, where “a” is from 0 to 50, “b” is from 50 to 99, and “c” is from 1 to 50.