Unstable regions in the disks with various surface densities: (a) ﹩f_{\Sigma }=0.3﹩, (b) ﹩f_{\Sigma }=1﹩ (the minimum‐mass solar nebula), (c) ﹩f_{\Sigma }=3﹩, and (d) ﹩f_{\Sigma }=10﹩. The other parameters are the same as those of the fiducial model. The solid and dashed curves represent the loci of ﹩\lambda _{\mathrm{res}\,}/ H=1﹩ for the cases of the field strength ﹩\beta _{c}=100﹩ and 1000, respectively, inside of which is magnetorotationally stable. The dotted curve represents the scale height of the disk ﹩z=H( r) ﹩.