小世界网络中的相分离和超大磁电阻效应

由于自旋、轨道、电荷和晶格的关联作用,具有超大磁电阻效应的锰氧化物表现出自发的相分离特征和复杂网络的输运特性.小世界网络是介于规则网络与无规网络之间的一种新的网络构形,它能够很好地描述锰氧化物的相分离特征.我们运用蒙特卡罗方法研究了基于小世界网络的一维伊辛自旋链中的磁输运性质,发现小世界关联会导致自发的长程序.随着小世界长程作用的增强,铁磁相的区域扩大,同时体系的磁性相变温度升高.相应的电阻网络模拟显示,在铁磁—顺磁转变温度附近,磁电阻效应有了很大的提高,很好地解释了锰氧化物中的相分离现象与超大磁电阻效应.

Phase separation and colossal magnetoresistance effect in a small-world network

Because of the interaction among spin,orbit,charge and lattice,manganites with colossal magnetoresistance effect exhibit spontaneous phase separation and complex network characteristic.Small-world network is a new type of network between regular network and random network which can describe the phase separation of manganites well.We use Monte Carlo simulation to study the magnetotransport of one dimensional Ising model in a small-world network. We find that the correlation of small-world network results in spontaneous long range order.With the increase of small-world network long range link,the ferromagnetic area become larger,the phase transition temperature increase accordingly.Resistance network simulation show that the magnetoresistance effect near phase transition temperature increase greatly,which explain the phase separation and colossal magnetoresistance effect of manganites well.