The Two Dimensional Antiferromagnetic Heisenberg Model with next Nearest Neighbour Ising Exchange
نویسندگان
چکیده
We have studied the S = 1/2 antiferromagnetic Heisenberg model in two dimensions, with an additional Ising next-nearest neighbour interaction. The next-nearest neighbour Ising interaction breaks the isotropy in spin space, for a ferromagnetic next-nearest neighbour interaction the system will order antiferromagnetically along the z axis. Antiferromagnetic next-nearest neighbour interactions will lead to frustration, and the system responds with flipping the spins down in the xy plane. For large next nearest neighbour coupling the system will order in a striped phase along the z axis, this phase is reached through a first order transition. We also consider the case of frustration through disorder on diagonal bonds, and find that any amount of diagonal-bond will tilt the magnetization away from the z axis.
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