NMR of 31P in CrRuP

NMR properties of 31P in CrRuP at low temperatures are reported. The compound CrRuP, which is a member of a series of compounds MRuP (M=3d transition metal), was expected to be in a nonmagnetic state at low temperature such as a Kondo insulator from the susceptibility data. However, field-swept and zero-field NMR spectra show that it is an antiferromagnet at low temperature. The hyperfine field at the 31P site at 4.2 K is determined to be 9.6 kOe with a half-width of 2.3 kOe. A simulation using the broad zero-field data and a simple antiferromagnetic spin structure explains the field-swept powder spectrum only qualitatively, suggesting a complex antiferromagnetic spin structure in this material.