Fig. 1: Concept of bi-reflection.
a A schematic of birefringence of a light. The transmitted light splits into two depending on the light polarization. b A schematic of reflection of a light. The light is totally reflected back at a boundary between materials. When boundary normal and an optical axis satisfies particular relation, reflected light wave may split into two. c A schematic of bi-reflection of spin waves. Spin waves, a collective wavy motion of electron spins in a magnetic material, reflect and split into two rays at the edge of out-of-plane magnetized film.
