Saunders T E, Chalker J T
Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP, United Kingdom.
Phys Rev Lett. 2007 Apr 13;98(15):157201. doi: 10.1103/PhysRevLett.98.157201. Epub 2007 Apr 9.
We investigate the consequences for geometrically frustrated antiferromagnets of weak disorder in the strength of exchange interactions. Taking as a model the classical Heisenberg antiferromagnet with nearest neighbor exchange on the pyrochlore lattice, we examine low-temperature behavior. We show that spatial modulation of exchange generates long-range effective interactions within the extensively degenerate ground states of the clean system. Using Monte Carlo simulations, we find a spin glass transition at a temperature set by the disorder strength. Disorder of this type, which is generated by random strains in the presence of magnetoelastic coupling, may account for the spin freezing observed in many geometrically frustrated magnets.
我们研究了交换相互作用强度中的弱无序对几何阻挫反铁磁体的影响。以具有最近邻交换作用的经典海森堡反铁磁体在烧绿石晶格上作为模型，我们研究了其低温行为。我们表明，交换作用的空间调制在清洁系统的广泛简并基态中产生了长程有效相互作用。通过蒙特卡罗模拟，我们发现在由无序强度设定的温度下存在自旋玻璃转变。这种类型的无序是由磁弹性耦合存在时的随机应变产生的，可能解释了在许多几何阻挫磁体中观察到的自旋冻结现象。
