Quantum spin Hall and quantum valley Hall effects in trilayer graphene and their topological structures
Ur Rehman Majeed1, 2, †, A Abid A1, 2
       

(color online) Four flavors of triple-vortex merons. (a) Flavor with valley and : the unit vector covers the upper hemisphere and displays a triple vortex meron-like configuration with associated topological charge . (b) Flavor with valley and : covers the lower hemisphere and displays a meron-like structure with . (c) Flavor with valley and : the mapping covers the upper hemisphere and displays a triple vortex anti-meron-like configuration with associated topological charge . (d) Flavor with valley and : covers the lower hemisphere and displays an anti-meron-like structure with .