Field-induced long-range-ordering in the S = 1 quasi-one-dimensional Heisenberg antiferromagnet Ni(C5H14N2)2N3(ClO4)

Abstract We have performed a heat capacity ( C p ) measurement using a relaxation method on a single-crystal sample of the S = 1 quasi-one-dimensional Heisenberg antiferromagnet Ni(C 5 H 14 N 2 ) 2 N 3 (ClO 4 ) in high magnetic fields and at low temperatures. An anomaly in C p has been observed at about 0.9 K and at 12 T. We interpret this anomaly as an indication of field induced long-range magnetic ordering.