College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, China.
Department of Physics, Tsinghua University, Beijing, 100084, China.
Sci Rep. 2017 Sep 5;7(1):10477. doi: 10.1038/s41598-017-10986-8.
The frustrated spin-1/2 J -J -J antiferromagnet with exchange anisotropy on the two-dimensional square lattice is investigated. The exchange anisotropy is presented by η with 0 ≤ η < 1. The effects of the J , J , J and anisotropy on the possible phase transition of the Néel state and collinear state are studied comprehensively. Our results indicate that for J > 0 there are upper limits [Formula: see text] and η values. When 0 < J ≤ [Formula: see text] and 0 ≤ η ≤ η , the Néel and collinear states have the same order-disorder transition point at J = J /2. Nevertheless, when the J and η values beyond the upper limits, it is a paramagnetic phase at J = J /2. For J < 0, in the case of 0 ≤ η < 1, the two states always have the same critical temperature as long as J = J /2. Therefore, for J = J /2, under such parameters, a first-order phase transition between the two states for these two cases below the critical temperatures may occur. When J ≠ J /2, the Néel and collinear states may also exist, while they have different critical temperatures. When J > J /2, a first-order phase transition between the two states may also occur. However, for J < J /2, the Néel state is always more stable than the collinear state.
二维正方形晶格上具有交换各向异性的受挫自旋 1/2 J-J-J 反铁磁体被研究。交换各向异性由 0 ≤ η < 1 的 η 来表示。全面研究了 J、J、J 和各向异性对奈尔态和共线态可能相变的影响。我们的结果表明，对于 J > 0，存在上限 [公式：见正文] 和 η 值。当 0 < J ≤ [公式：见正文] 和 0 ≤ η ≤ η 时，奈尔态和共线态在 J = J /2 处具有相同的有序-无序相变点。然而，当 J 和 η 值超过上限时，在 J = J /2 处为顺磁相。对于 J < 0，在 0 ≤ η < 1 的情况下，只要 J = J /2，两种状态始终具有相同的临界温度。因此，对于 J = J /2，在这些参数下，两种情况下低于临界温度的两种状态之间可能发生一级相变。当 J ≠ J /2 时，也可能存在奈尔态和共线态，而它们具有不同的临界温度。当 J > J /2 时，两种状态之间也可能发生一级相变。然而，对于 J < J /2，奈尔态总是比共线态更稳定。
