Nonlinear emergent elasticity and structural transitions of a skyrmion crystal under uniaxial distortion

作者：Yangfan Hu, Xiaoming Lan, Biao Wang · 发表于：Physical review. B./Physical review. B · 年份：2019 · DOI：10.1103/physrevb.99.214412 · 被引用次数：13 · 研究领域：Magnetic properties of thin films、Magnetic and Electromagnetic Effects、Metallic Glasses and Amorphous Alloys

Emergent crystals are the periodic alignment of ``emergent particles,'' i.e., localized collective behavior of atoms or their charges, spins, or orbits. The elasticity of these novel states of matter suffering mechanical loads can be strikingly softer than that of the underlying material, showing great strain-mediated tunability. However, the deformation and possible failure of emergent crystals under strong strain, vital for realizing related applications, are hitherto unclear. Here we theoretically study the nonlinear elasticity and structural transitions of a Skyrmion crystal (SkX) suffering uniaxial distortion. Under moderate tension, a SkX behaves like a ductile material, with an exotic negative crossover elastic stiffness and a negative emergent Poisson's ratio at appropriate conditions of magnetic field. Under strong strain, we observe at most six phase transitions, generating four novel emergent crystals that are thermodynamically metastable. We argue that this nondestructive polymorphism is a general feature for any emergent crystals exposed to mechanical loads.