μSR Study of Cu Benzoate at Very Low Temperature - Existence or Nonexistence of Long Range Order in Coupled Chains -

抄録

Zero-, longitudinal- and transverse-field μSR experiments are performed for a linear chain antiferromagnet Cu benzoate, Cu(C₆H₅COO)·3H₂O, and no long range order (LRO) is found down to 20 mK. The upper limit of the ratio of the Néel temperature to the exchange coupling, k_BT_N/J<0.002, is even better than that of Sr₂CuO₃, which is known as the best candidate of S=1/2 antiferromagnetic Heisenberg quantum spin chain. Significance of our findings is discussed in view of whether there is a non-zero critical coupling ratio necessary for LRO in coupled Heisenberg chains.