Magnetic properties of the S=1/2 antiferromagnetic triangular lattice LiNiO2

The authors measured susceptibility, resistivity and specific heat of the S=1/2 anti-ferromagnetic triangular lattice LiNiO 2 . In addition to the formerly recognized characteristic temperatures T N1 ( approximately 210 K) and T N2 ( approximately 20 K), they found another characteristic temperature T N3 ( approximately 70 K) from the susceptibility measurement, at which three-dimensional short-range order presumably sets in at the expense of the planar frustration. In the range between T N1 and T N3 , an exponentially increasing susceptibility with decreasing temperature was disclosed, which is believed to be one of the characteristic features of the planar frustration in this system. The specific heat results revealed that the magnetic entropy gradually decreases from R In 2 without any pronounced anomalies corresponding to a long-range magnetic order down to 0.4 K. The nature of the ordering process of LiNiO 2 is discussed by referring these characteristic temperatures.