Abstract
We determine the magnetic properties of the two-dimensional n=0 vector model using transfer matrix calculations and finite-size scaling. In the high-temperature region, we obtain results similar to the mean-field picture. In the low-temperature region, we find a very different behavior with a susceptibility which is always negative and an infinite spontaneous magnetization. This is shown to be in agreementn with some works of Nienhuis. The physical interpretation is discussed.