Enhancing Magnetic Functionality with Scandium: Breaking Stereotypes in the Design of Rare Earth Materials

Replacement of strongly magnetic gadolinium with weakly magnetic scandium unexpectedly enhances ferromagnetic interactions in (Gd1–xScx)5Ge4. Based upon this counterintuitive experimental finding we demonstrate the unique role 3d1 electrons of scandium atoms play in mediating magnetic interactions between the gadolinium atoms from the neighboring layers in the Sm5Ge4-type crystal lattice. Scandium substitutions at and below 20% rapidly increase the Curie temperature, TC, of the Gd5Ge4 parent, eliminate both the kinetic arrest and hysteresis, and drastically improve reversibility of the first-order magnetostructural transformation at TC. In agreement with first-principles predictions, higher than 20% Sc leads to the formation of a closely related Pu5Rh4-type structure where the first-order magnetostructural transformation is replaced by a conventional second-order ferromagnetic ordering that remains accompanied by a continuous rearrangement of the crystal lattice. Comparison of two materials with similar s...