On the doping variation of the pseudogap in high-T-c cuprates

We briefly summarize well established and the latest experimental results c oncerning the doping dependence of the so-called pseudogap (T*) and emphasi ze that surface related techniques, like ARPES or tunneling, give somewhat higher value of T* as compared to the bulk techniques, like specific heat. In the underdoped regime most theoretical models differ in extrapolating th e T*-line to zero doping. As underdoped cuprates are rather inhomogeneous a nd the disorder plays an important role, the complete microscopic theory wi ll have to take into account all these subtle effects. (C) 2001 Elsevier Sc ience B.V. All rights reserved.