Quantum spin chain as a potential realization of the Confederate Flag model

It is well established that long-range magnetic order is suppressed in magnetic systems whose interactions are low dimensional. The prototypical example is the S-12 Heisenberg antiferromagnetic chain (S-12 HAFC) whose ground state is quantum critical. In real S-12 HAFC compounds interchain coupling induces long-range magnetic order although with a suppressed ordered moment and reduced Néel temperature compared to the Curie-Weiss temperature. Recently, it was suggested that order can also be suppressed if the interchain interactions are frustrated, as for the Confederate Flag model. Here, we study the new S-12 HAFC, (NO)[Cu(NO3)3]. This material shows extreme suppression of order which furthermore is incommensurate revealing the presence of frustration consistent with the Confederate Flag model. © 2014 American Physical Society