Multiband effects on β -FeSe single crystals

We present the upper critical fields mu sub(0)H sub(c2)(T) and Hall effect in beta -FeSe single crystals. The mu sub(0)H sub(c2)(T) increases as the temperature is lowered for fields applied parallel and perpendicular to (101), the natural growth facet of the crystal. The mu sub(0)H sub(c2)(T) for both field directions and the anisotropy at low temperature increase under pressure. Hole carriers are dominant at high magnetic fields. However, the contribution of electron-type carriers is significant at low fields and low temperature. Our results show that multiband effects dominate mu sub(0)H sub(c2)(T) and electronic transport in the normal state.