Abstract

Antiferromagnetically interacting Heisenberg spins locating on a triangle lattice, such as those in PdCrO₂, generally order into a commensurate 120-degree phase below Neel temperature. In our work, we use a newly developed piezo-actuated strain rig, which is able to apply both positive and negative uniaxial pressure to about 1 GPa, to conduct uniaxial pressure studies on PdCrO₂. By cancelling the strain due to the thermal contraction of sample holders, we achieve the true zero strain, and discover a line of first order transition well below Neel temperature. This suggests that further degree of freedom is frozen. Furthermore, we probe the response of the triangular antiferromagnet to anisotropic lattice distortion. At lattice compression of about 0.4%, we find signatures in resistivity, magnetoresistivity and Hall effect, which may indicate a commensurate-to-incommensurate transition.