The innovation engine for new materials

Piush Behera

Piush Behera


Materials Science and Engineering


University of Illinois Urbana-Champaign


Emily Levin

Faculty Sponsor(s): 

Tresa Pollock
Ram Seshadri

Faculty Sponsor's Department(s): 


Project Title: 

Magnetism in Copper and Gold Based Heuslers

Project Description: 

Heusler intermetallics are a class of compounds that share the same crystal structure and chemical formula XY2Z, where X and Y are transition metals, and Z is a main group element. These intermetallics exhibit many unique and desirable properties such as thermoelectricity, magnetic shape memory, and even superconductivity. Previous neutron diffraction studies have shown that the Heusler MnAu2Al exhibits a coexistence of ferromagnetism and spiral magnetism at low temperature, while isoelectronic MnCu2Al is only ferromagnetic. We propose the spiral magnetic structure of MnAu2Al is due to spin-orbit coupling resulting from the gold atoms. Spin-orbit coupling, or the interaction between an electron’s spin and orbital motion, scales with Z4, where Z is atomic number, making the effect much stronger for heavy elements such as gold. Samples of each MnAu2Al and MnCu2Al were made through rapid assisted microwave heating and arc melting. Samples were first characterized using a combination of X-ray diffraction and scanning electron microscopy, which elucidated the phases present and their compositions in each sample. This allowed us to tune the starting composition until we obtained a phase pure sample. Magnetic measurements of MnAu2Al indicate an antiferromagnetic (spiral) phase below 110K, with a metamagnetic transition to ferromagnetic at an applied field of 2 T. Future work will use computational tools to determine if the energy needed to induce spiral magnetism corresponds to the energy attributed to spin-orbit coupling. This understanding of the effects of spin-orbit coupling will be useful in tuning magnetic properties of other materials by simply changing their chemistry.