Uniaxial-Pressure-Induced Release of Magnetic Frustration in a Triangular Lattice Antiferromagnet YbCuGe

We have studied the effect of geometrical frustration on the antiferromagnetic order in the Yb-based triangular lattice compound YbCuGe below TN = 4.2 K by the measurements of magnetization and specific heat under hydrostatic and uniaxial pressures. By applying hydrostatic pressure P up to 1.34 GPa, TN hardly changes. By contrast, TN increases as P is applied along the hexagonal a axis, while TN decreases by the application of P along the c axis. The increase of TN only for P‖a suggests the release of the frustration inherent in the triangular lattice of Yb ions of this compound.