De Poortere E P, Tutuc E, Papadakis S J, Shayegan M
Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
Science. 2000 Nov 24;290(5496):1546-9. doi: 10.1126/science.290.5496.1546.
We report a manifestation of first-order magnetic transitions in two-dimensional electron systems. This phenomenon occurs in aluminum arsenide quantum wells with sufficiently low carrier densities and appears as a set of hysteretic spikes in the resistance of a sample placed in crossed parallel and perpendicular magnetic fields, each spike occurring at the transition between states with different partial magnetizations. Our experiments thus indicate that the presence of magnetic domains at the transition starkly increases dissipation, an effect also suspected in other ferromagnetic materials. Analysis of the positions of the transition spikes allows us to deduce the change in exchange-correlation energy across the magnetic transition, which in turn will help improve our understanding of metallic ferromagnetism.
我们报道了二维电子系统中一阶磁转变的一种表现形式。这种现象发生在载流子密度足够低的砷化铝量子阱中，表现为置于交叉平行和垂直磁场中的样品电阻出现一组磁滞尖峰，每个尖峰出现在具有不同部分磁化状态之间的转变处。我们的实验因此表明，转变处磁畴的存在显著增加了耗散，这一效应在其他铁磁材料中也被怀疑存在。对转变尖峰位置的分析使我们能够推断出磁转变过程中交换关联能的变化，这反过来将有助于增进我们对金属铁磁性的理解。
