Orbital Order, Metal Insulator Transition, and Magnetoresistance-Effect in the
Orbital Order, Metal Insulator Transition, and Magnetoresistance-Effect in the
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轨道有序、金属绝缘体跃迁和磁阻效应
DOI：
10.1103/physrevb.83.125110
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T.Pruschke
中科院分区：
文献类型：
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作者：
R.Peters;N.Kawakami;T.Pruschke
我们研究了动态平均场理论中温度和磁场对双轨道哈伯德模型的影响。我们关注四分之一填充系统，由于轨道简并，这是相图中的一个特殊点。在这种特定的填充下，模型表现出两种不同的长程有序机制，即轨道有序和铁磁性。两者可以合作但不依赖对方的存在，创造出丰富的相图。特别是，在向轨道有序铁磁态的相变附近，我们观察到强磁阻效应。除了低温相变之外，我们还观察到顺磁绝缘态和顺磁金属态之间的交叉，以增加高温下的洪德耦合。
We study the effects of temperature and magnetic field on a two-orbital Hubbard model within dynamical mean-field theory. We focus on the quarter filled system, which is a special point in the phase diagram due to orbital degeneracy. At this particular filling the model exhibits two different long-range order mechanisms, namely orbital order and ferromagnetism. Both can cooperate but do not rely on each other’s presence, creating a rich phase diagram. Particularly, in the vicinity of the phase transition to an orbitally ordered ferromagnetic state, we observe a strong magnetoresistance effect. In addition to the low temperature phase transitions, we also observe a crossover between a paramagnetic insulating and a paramagnetic metallic state for increasing Hund’s coupling at high temperatures.