Point contact spectrscopy of electron-doped cuprates in a magnetic field of 32 tesla

Electron-doped cuprates have low values of the upper critical field ($H_{c2} \sim 10$ T at 1.5 K) and hence it is possible to study their normal state at low temperatures. Such studies have been done before and showed evidence of a ``pseudogap". However, to understand the origin of this pseudogap and which model of high-$T_c$ superconductivity it supports, it is necessary to study the effect of high magnetic fields on this pseudogap. We have performed point contact spectroscopy experiments using junctions between a normal metal (Pt-Rh) and electron-doped Pr$_{2-x}$Ce$_x$CuO$_4$ (PCCO) films for $0.13 < x < 0.17$. To probe the normal state at low temperatures ($\sim$ 0.4 K), we suppressed the superconductivity by applying high magnetic fields (up to 32T). We will show the effects of such high fields on the pseudogap and discuss our results in the context of present theories {\em viz.} preformed pairs and the presence of a quantum critical point.