Anisotropic suppression of the energy gap in CeNiSn by high magnetic fields

The formation of the pseudogap in CeNiSn has been investigated by means of resistivity and specific-heat measurements in high magnetic fields. When the field is raised from 0 to 12 T along the orthorhombic a axis, the semiconductorlike behavior in the resistivity below 6 K disappears and the linear electronic term in the specific heat increases from 57 to 100 mJ/${\mathrm{K}}^2$ mol. However, no significant effect was observed for fields along the b and c axes up to 15 T. These results suggest an anisotropic suppression of the pseudogap, which can be interpreted as a result of strong spin polarization of the renormalized narrow band.