Monotonic Increase of Upper Critical Field with Hole Doping in High-Tc Cuprate Bi2+xSr2-xCaCu2O8+d

The upper critical field Hc2(0) of high-Tc cuprate Bi2+xSr2-xCaCu2O8+d increases monotonically with hole doping from the underdoped to the overdoped regime, in contrast to the parabolic doping dependence of the critical temperature Tc.