Low Temperature NMR Studies of YbSb

Nuclear Magnetic Resonance of YbSb was measured below 1 K to investigate a phase transition around 0.5 K including sample dependence. The observed broadening of spin echo spectra below 0.4 K demonstrates the existence of a phase transition clearly. The width of spin echo spectra are comparable to those of YbAs below 0.4 K, which is suggests the ordered moments are also comparable although the shape of spin echo spectra are quite different. The temperature dependence of relaxation rate shows rather abrupt decrease below 0.4 K. This is not consistent with the previous µSR measurements.