Heisenberg antiferromagnetic model

In order to further test this model of intrinsic random fields in the crossover regime to SG order, neutron diffraction experiments on the diluted Heisenberg antiferromagnetic system Eu Srj.j Te are underway (see its preliminary magnetic phase diagram in fig. 7b). As described in sec. 6.1, the borderline between SG and AFM behavior in Eu4.Sr,, Te has been determined up to now (Borgermann... 

We now map this quantum phase transition onto a classical transition. Chakravarty and co-workers ° showed that the low-energy behavior of two-dimensional quantum Heisenberg antiferromagnets is generally described by a (2 - - l)-dimensional quantum rotor model with the Euclidean action... 

An interesting feature of the spin system of this LB film was revealed by temperature dependent ESR measurements [76-78]. The temperature dependence of spin susceptibility of the LB film together with that of powder sample is shown in Figure 14.10. The magnetic properties in both LB and powder state were adequately explained by the random-exchange Heisenberg antiferromagnetic chain (REHAC) model. 

Random-exchange Heisenberg antiferromagnetic chain (REHAC) model, 735... 

Temperature dependence of magnetic susceptibility of the PF6 salt was measured from 300 to 4 K at 5 T [35], The spin susceptibility of this salt gradually decreases from 300 to 50 K. Below 50 K, the susceptibility exhibits a rapid decrease accompanied by anisotropic temperature dependence, which is an indication of the long-range antiferromagnetic ordering. A one-dimensional Heisenberg model is... 

For a two-qubit isotropic Heisenberg model, there exists thermal entanglement for the antiferromagnetic case and no thermal entanglement for the... 

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