论文标题

高阶范霍夫点竞争订单

Competing orders at higher-order Van Hove points

论文作者

Classen, Laura, Chubukov, Andrey V., Honerkamp, Carsten, Scherer, Michael M.

论文摘要

Van Hove点是能量分散的特殊点,状态的密度表现出分析性奇异性。当van霍夫点接近费米水平时,通常会在一个以上的通道中增强对密度波顺序,pomeranchuk订单和超导性的趋势,都可以增强,从而导致不同的订单和非常规地面状态之间的竞争。在这里,我们考虑了高阶范霍夫点的影响,该点的分散体比传统的范霍夫点附近,状态的密度具有幂律差异。我们认为,这种点存在于插入的石墨烯和其他材料中。我们使用有效的低能模型对高阶范霍夫点附近的电子模型,并使用公正的重新归一化组方法分析了不同订购趋势之间的竞争。对于纯粹的排斥相互作用,我们发现两个关键的竞争者是铁磁性和手性超导性。对于一个小小的吸引人的交换相互作用,我们找到了一种新型的自旋Pomeranchuk顺序,其中自旋顺序参数在费米表面周围风。在我们的情况下,预测单个高阶范霍夫点的超级金属状态是一个不稳定的固定点。

Van Hove points are special points in the energy dispersion, where the density of states exhibits analytic singularities. When a Van Hove point is close to the Fermi level, tendencies towards density wave orders, Pomeranchuk orders, and superconductivity can all be enhanced, often in more than one channel, leading to a competition between different orders and unconventional ground states. Here we consider the effects from higher-order Van Hove points, around which the dispersion is flatter than near a conventional Van Hove point, and the density of states has a power-law divergence. We argue that such points are present in intercalated graphene and other materials. We use an effective low-energy model for electrons near higher-order Van Hove points and analyze the competition between different ordering tendencies using an unbiased renormalization group approach. For purely repulsive interactions, we find that two key competitors are ferromagnetism and chiral superconductivity. For a small attractive exchange interaction, we find a new type of spin Pomeranchuk order, in which the spin order parameter winds around the Fermi surface. The supermetal state, predicted for a single higher-order Van Hove point, is an unstable fixed point in our case.

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