Table 1 The lattice constant a, Bi-Bi and Sb-Sb bond length b, Bi-X and Sb-X bond length d, buckling height h shown in Figure 1a (h is defined as the distance from the center of the upper to that of the lower Bi/Sb atoms), global band gap Δ (the superscripts d and i represent the direct gap and indirect gap, respectively)

From: Quantum spin Hall insulators and quantum valley Hall insulators of BiX/SbX (X=H, F, Cl and Br) monolayers with a record bulk band gap

Monolayers

a (Å)

b (Å)

d (Å)

h (Å)

Δ (eV)

v F (10 5 m/s)

λ SO

Z 2

BiH

5.53

3.19

1.82

0.08

1.03i

8.9

0.56

1

BiF

5.38

3.14

2.12

0.46

1.08i

7.2

0.55

1

BiCl

5.49

3.17

2.54

0.24

0.95i

6.9

0.56

1

BiBr

5.52

3.18

2.69

0.16

0.74i

8.0

0.65

1

SbH

5.29

3.05

1.73

0.08

0.41d

8.6

0.21

1

SbF

5.12

2.96

1.99

0.30

0.32d

7.9

0.16

1

SbCl

5.17

2.98

2.42

0.14

0.36d

7.7

0.18

1

SbBr

5.25

3.03

2.57

0.09

0.40d

8.6

0.20

1

  1. Fermi velocity vF and magnitude of the intrinsic effective SOC λSO for Bi and Sb hydride/halide monolayers obtained from the first-principles calculations. Note that λSO=Eg/2, with the local gap Eg opened by SOC at the Dirac point.
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