Magnetostrictive materials are those that expand or contract because of a change in magnetization, converting magnetic energy into kinetic energy. Some materials with useful magnetostrictive properties have been found in Laves phases, which have the general form AB2. In recent decades, interest in Laves phases – especially those combining A elements from the early 3d, 4d, and 5d groups with B elements from the late 3d elements – has piqued as they have been found to be viable for applications ranging from hydrogen storage to structural applications such as in turbines due to their contribution to high strength. Additionally, many exhibit exciting and exotic magnetic properties, including interesting magnetic structures, superconductivity, and magnetostriction. YMn2, a cubic Laves phase, shows particularly interesting coupling between its magnetic properties and its structure. It is a geometrically frustrated material, being partly comprised of the pyrochlore lattice, and at its magnetic transition, it undergoes a structural transition as well as a large (5%) volume change. Furthermore, this magnetostructural transition exhibits a large (approx. 30 K) and reproducible thermal hysteresis depending on the direction of the temperature sweep. Here we discuss our efforts to understand and develop control over the coupling of strain and magnetization in this intermetallic using chemical substitution as a tuning parameter. Specifically, we are to creating solid solutions with other AB2 compounds with non-cubic structures to understand if morphotropic phase boundaries can be designed into this system to enhance magnetoelastic coupling. We seek to understand how chemical substitution affects the ordering temperature, thermal hysteresis, and magnitude of the volume change in YMn2.

Magnetovolume effects in geometrically frustrated Laves phases

2019 Spring National Meeting

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