Chemical pressure effect on dynamic spin properties in CrAs*

CrAs is an antiferromagnetic metal, which shows a helical spin structure accompanied by an abrupt lattice expansion at $T\rm_{N}$$\sim$260 K in ambient pressure. With applying pressure, the magnetic transition is suppressed and superconductivity appears with a maximum transition temperature of $\sim$2 K. Since Cr has the spin degree of freedom, elucidating the magnetic contribution to the superconductivity is crucial to understand the pairing mechanism. However, inelastic neutron scattering (INS) measurement under high pressure is challenging due to sample space limitation. Therefore, we studied chemical pressure effect by substituting As by P, which is found to be almost the same as the external pressure. We performed INS experiments in undoped and P-doped CrAs using powder samples. The results in the P-doped CrAs clearly indicate that the antiferromagnetic fluctuations still remain above the critical P content, where the long range magnetic order is suppressed, suggesting a coupling between the magnetism and the superconductivity.