The foot, the fan, and the cuprate phase diagram: Fermi-volume-changing quantum phase transitions

IF 1.3 3区物理与天体物理 Q4 PHYSICS, APPLIED

Physica C-superconductivity and Its Applications Pub Date : 2025-04-09 DOI:10.1016/j.physc.2025.1354707

Subir Sachdev

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引用次数: 0

Abstract

A Fermi liquid with a ‘large’ Fermi surface (FL) can have a quantum phase transition to a spin density wave state (SDW) with reconstructed ‘small’ Fermi pockets. Both FL and SDW phases obey the Luttinger constraints on the volume enclosed by the Fermi surfaces. Critical spin fluctuations lead to spin-singlet

d

-wave pairing, as observed in the cuprates. Studies of the influence of spatial disorder on the FL-SDW quantum phase transition predict an extended quantum-critical Griffiths-type phase at low temperatures on the large Fermi surface side. These computations agree with the ‘foot’ of strange metal transport, and recent low temperature neutron scattering observations on La

_{2 - x}

_{x}

CuO

_{4}

However, this theory cannot explain the higher temperature pseudogap and the ‘fan’ of strange metal behavior of the hole-doped cuprates. Here we need to consider underlying Fermi-volume-changing quantum phase transitions without symmetry breaking. Then the small Fermi surface phase does not obey the Luttinger constraint, and the pseudogap metal is described by thermal fluctuations above a ‘fractionalized Fermi liquid’ (FL*) or a ‘holon metal’, with the descriptions related by a duality on a background spin liquid. The quantum critical fan is described using a field theory for an underlying FL-FL* quantum phase transition in the presence of spatial disorder. This field theory can be mapped to a form which can be analyzed using the methods of the Sachdev–Ye–Kitaev model. Such an analysis successfully models linear-in-temperature resistivity, optical conductivity and thermopower observations in the quantum critical fan.

The confinement crossover connecting these lower and higher temperature descriptions is also discussed.

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脚、扇子和铜相图：费米变体积量子相变

具有“大”费米表面（FL）的费米液体可以具有重构的“小”费米口袋的量子相变到自旋密度波态（SDW）。在费米面包围的体积上，FL相和SDW相都服从Luttinger约束。临界自旋涨落导致自旋单线态d波配对，正如在铜酸盐中观察到的那样。空间无序对FL-SDW量子相变影响的研究预测了在大费米面侧低温下扩展的量子临界格里菲斯型相。这些计算结果与奇怪金属输运的“脚”和La2−xSrxCuO4上最近的低温中子散射观测结果一致。然而，该理论不能解释空穴掺杂铜酸盐的高温赝隙和奇异金属的“扇形”行为。这里我们需要考虑没有对称破缺的潜在的费米体积变化量子相变。然后，小费米表面相不服从Luttinger约束，伪间隙金属由“分数化费米液体”（FL*）或“全息金属”上方的热涨落描述，并与背景自旋液体上的二象性相关。利用场理论描述了空间无序存在下底层FL-FL*量子相变的量子临界扇。这个场论可以映射成一种形式，可以用Sachdev-Ye-Kitaev模型的方法来分析。这样的分析成功地模拟了量子临界风扇的线性温度电阻率、光学电导率和热功率观测。还讨论了连接这些低温度和高温度描述的约束交叉。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Physica C-superconductivity and Its Applications 物理-物理：应用

CiteScore

2.70

自引率

11.80%

发文量

102

审稿时长

66 days

期刊介绍： Physica C (Superconductivity and its Applications) publishes peer-reviewed papers on novel developments in the field of superconductivity. Topics include discovery of new superconducting materials and elucidation of their mechanisms, physics of vortex matter, enhancement of critical properties of superconductors, identification of novel properties and processing methods that improve their performance and promote new routes to applications of superconductivity. The main goal of the journal is to publish: 1. Papers that substantially increase the understanding of the fundamental aspects and mechanisms of superconductivity and vortex matter through theoretical and experimental methods. 2. Papers that report on novel physical properties and processing of materials that substantially enhance their critical performance. 3. Papers that promote new or improved routes to applications of superconductivity and/or superconducting materials, and proof-of-concept novel proto-type superconducting devices. The editors of the journal will select papers that are well written and based on thorough research that provide truly novel insights.