NMR Measurements on a Triangular-Lattice Antiferromagnet YbCuGe

We report Cu-NMR measurements on a metallic triangular-lattice antiferromagnet YbCuGe.There is an antiferromagnetic ordering below T N = 4.2 K.The released entropy at T N is 28 % of Rln2.As there is no indication of Kondo effect in the resistivity and in the small linear coefficient of the specific heat (γ), the small entropy at T N suggests the geometrical frustration effect.The gradual increase of the spectral width and the abrupt decrease of the spin-lattice relaxation rate T -1 1 below T N demonstrate the occurrence of the magnetic ordering.In contrast to T -1 1 , the spin-spin relaxation rate T -1 2 increases below T N .These properties suggest that the slow spin fluctuations remain in the magnetically ordered state in this compound.