RESUMO
Spin-valley locking in monolayer transition metal dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic state has sparsely been seen in bulk materials. Here, we report spin-valley locking in a Dirac semimetal BaMnSb2. This is revealed by comprehensive studies using first principles calculations, tight-binding and effective model analyses, angle-resolved photoemission spectroscopy measurements. Moreover, this material also exhibits a stacked quantum Hall effect (QHE). The spin-valley degeneracy extracted from the QHE is close to 2. This result, together with the Landau level spin splitting, further confirms the spin-valley locking picture. In the extreme quantum limit, we also observed a plateau in the z-axis resistance, suggestive of a two-dimensional chiral surface state present in the quantum Hall state. These findings establish BaMnSb2 as a rare platform for exploring coupled spin and valley physics in bulk single crystals and accessing 3D interacting topological states.
RESUMO
OBJECTIVE: To evaluate the clinical efficacy of thin flap with subdermal vascular network of the neck-pectoral region on repair of the contracture of the burn scar on the neck. METHODS: From March 1990 to May 1998, 21 cases of deformity of neck due to burn scar were repaired with the thin flap ranging from 8 cm x 5 cm to 14 cm x 8 cm, and all of the cases were followed up for 6 to 42 months. RESULTS: Except partial necrosis of the distal end of the flap in 1 case, the flaps in the other 20 cases all survived and presented a satisfactory appearance and function. CONCLUSION: The thin flap with subdermal vascular network in neck-pectoral region may provide a large area of flap, and could be easily transferred. It's an ideal flap for the repair of skin defect on the neck.