The effect of high pressure on antiferromagnetic correlations in the Kondo semimetal CeNiSn

Magnetic excitation spectra of the Kondo semimetal CeNiSn have been studied by neutron scattering under hydrostatic pressure up to 11 kbar. The inelastic peak at <(h)over bar omega> = 4 meV has been observed at the ambient pressure below T-coh = 20 K and is regarded as a dynamic antiferromagnetic correlation. As pressure is applied, the 4 meV peak shifts to a higher-energy region and becomes weak. Since the pseudogap is known to be suppressed under high pressure, this result strongly suggests that the antiferromagnetic correlation is closely related to pseudogap formation.