Synthesis and Strain Gradient Induced Flexomagnetism in Rippled GdAuGe Heusler Membranes*

Elastic strain is a powerful tool for tuning the ferroic properties of materials. Freestanding membranes of crystalline materials provide unique opportunities to apply large strains and strain gradients beyond the limits that exist for bulk crystals and epitaxially clamped films. Here we present the synthesis of single crystalline GdAuGe membranes by molecular beam epitaxy on graphene-terminated germanium substrates. By employing a seeded growth approach, we overcome the challenges associated with wetting on low surface energy graphene, resulting in smooth, highly ordered films. However, the introduction of strain gradient in the rippled membranes induces an antiferromagnetic to ferrimagnetic transition. First principles calculations suggest a dominant role of strain gradients, rather than homogeneous strain, on inducing the ferrimagnetic states. We will discuss local mapping of magnetization by scanning probe and optical measurements to unravel the underlying mechanisms and advance our understanding of these phenomena in GdAuGe Heusler membranes.