Thermopower of CeNiSn under a magnetic field

We have measured the thermopower along the three crystallographic axes of single crystals at 1.3 K and 4.2 K under a magnetic field up to 10 T applied perpendicularly to the direction of the temperature gradient. There are six cases altogether for the direction of the magnetic field relative to the temperature gradient along the crystal axis. The value of the thermopower was found to decrease drastically as the increase of the magnetic field applied in parallel only to the a-axis, the axis having the largest magnetic susceptibility, inferring the destruction of the band gap due to the magnetic field.