Investigations of the nature of the 0.4K phase transition in YbBiPt

We report results of resistivity measurements at ambient and hydrostatic pressures of up to ≈ 6 kbar. Large resistivity anisotropy sets in below the phase-transition temperature of 0.4 K. In some directions the resistivity increases below 0.4 K, which we interpret as partial gapping of the Fermi surface. Hydrostatic pressure of less than 1 kbar suppresses the low-temperature phase entirely. © 1994