Hidden magnetism at the pseudogap critical point of a cuprate superconductor

Abstract

The mysterious pseudogap phase of cuprate superconductors ends at a critical hole doping level p* but the nature of the ground state below p* is still debated. Here, we show that the genuine nature of the magnetic ground state in La 2x Sr x CuO 4 is hidden by competing effects from superconductivity: applying intense magnetic fields to quench superconductivity, we uncover the presence of glassy antiferromagnetic order up to the pseudogap boundary p* ≈ 0.19, and not above. There is thus a quantum phase transition at p*, which is likely to underlie highfield observations of a fundamental change in electronic properties across p*. Furthermore, the continuous presence of quasi-static moments from the insulator up to p* suggests that the physics of the doped Mott insulator is relevant through the entire pseudogap regime and might be more fundamentally driving the transition at p* than just spin or charge ordering.

High magnetic field ultrasound study of spin freezing in La1.88Sr0.12CuO4

“…While we observe the same behaviour in LSCO p = 0.12 for B ≤ 2T (see Appendix B for more details), this scenario does not hold at higher field where we observe an increase of T min . All measurements reported here in LSCO p = 0.12 support the interpretation that the ultrasound anomalies are caused by the AFM glass phase via spin-phonon coupling [18].…”

“…Different interpretations have been proposed to explain this peculiar behaviour [11][12][13][15][16][17]. Recently, using NMR and sound velocity measurements in high magnetic field in LSCO for p ≥ 0.145, we have shown that the anomalous sound velocity appears to be caused by a coupling of the AFM glass to the lattice [18].…”

“…The hole doping p = 0.122 ± 0.002 has been determined by measuring T st = 252 K, the temperature of the HTT-OMT structural phase transition by sound velocity, as described in Ref. [18]. The different samples share a similar T st and thus a similar doping.…”

Recent progress in NMR studies on high-<italic>T</italic><sub>c</sub> superconductors

“…, 引起了国际上的广泛关注. 铁基超 图29 (网络版彩图)不同掺杂和磁场下 139 La原子核的1/T 1 T随温度的变化 [85] . 导体发展至今, 已在多种不同的铁基材料中陆续发现 了高温超导现象 [88][89][90][91][92] .…”

Bilocal quantum criticality

“…Our interest in studying gauge theories of critical points in metals was motivated by numerous experimental indications [1][2][3][4][5][6][7][8][9][10][11][12][13][14] of optimal doping criticality in the hole-doped cuprate superconductors. We examine here further aspects of a recently proposed [15,16] SU (2) gauge theory for the vicinity of optimal doping in which a parent conformal theory is coupled to a large Fermi surface of gauge-neutral electrons.…”