Vanishing Hall Coefficient in the Extreme Quantum Limit in Photocarrier-Doped SrTiO3

Vanishing pseudogap around $(π,0)$ in an electron-doped high-$\mathrm{T_{c}}$ superconductor: a simple picture

Recent ARPES measurement on electron-doped cuprate $\mathrm{Pr}_{1.3-x}\mathrm{La}_{0.7}\mathrm{Ce}_{x}\mathrm{CuO}_{4}$ finds that the pseudogap along the boundary of the antiferromagnetic Brillouin zone(AFBZ) exhibits dramatic momentum dependence. In particular, the pseudogap vanishes in a finite region around the anti-nodal point, in which a single broadened peak emerges at the un-renormalized quasiparticle energy. Such an observation is argued to be inconsistent with the antiferromagnetic(AFM) band-folding picture, which predicts a constant pseudogap along the AFBZ boundary. On the other h…

Superconductivity by Hidden Spin Fluctuations in Electron-Doped Iron Selenide

Berg, Metlitski and Sachdev, Science 338, 1606 (2012), have shown that the exchange of hidden spin fluctuations by conduction electrons with two orbitals can result in high-temperature superconductivity in copper-oxide materials. We introduce a similar model for high-temperature iron-selenide superconductors that are electron doped. Conduction electrons carry the minimal 3d xz and 3d yz iron-atom orbitals. Low-energy hidden spin fluctuations at the checkerboard wavevector Q_AF result from nested Fermi surfaces at the center and at the corner of the unfolded (one-iron) Brillouin zone. Magnetic …

Calculation of generalized spin stiffness constant of strongly correlated doped quantum antiferromagnet on two-dimensional lattice and it's application to effective exchange constant for semi-itinerant systems

The generalized spin stiffness constant for a doped quantum antiferromagnet has been investigated both analytically and numerically as a function of doping concentration at zero temperature, based on the strongly correlated t-J model on two-dimensional square lattice. The nature of the theoretical dependence of the stiffness constant on doping shows a striking similarity with that of the effective exchange constant, obtained from the combination of other theoretical and experimental techniques in the low doping region. This correspondence once again establishes that spin stiffness can very wel…

具有奇宇称ALM的空穴掺杂双层Haldane-Hubbard模型中的自旋霍尔电导率

The spin Hall conductivity in the hole-doped bilayer Haldane-Hubbard model with odd-parity ALM

基于空穴掺杂单层Haldane-Hubbard模型的研究，提出双层HH模型，通过层间时间反演变换实现补偿的奇宇称自旋劈裂和$T$偶自旋霍尔电导率，为共线磁体中同时实现这两种现象提供通用框架。

Quantum critical 5f-electrons avoid singularities in U(Ru,Rh)2Si2

We present specific heat measurements of 4% Rh-doped U(Ru,Rh)2Si2 at magnetic fields above the proposed metamagnetic transition field Hm~34 T, revealing striking similarities to the isotructural Ce analog CeRu2Si2, suggesting that strongly renormalized hybridized band models apply equally well to both systems. The vanishing bandwidths as H --> Hm are consistent with a putative quantum critical point close to Hm. The existence of a phase transition into an ordered phase in the vicinity of Hm for 4% Rh-doped U(Ru,Rh)2Si2, but not for CeRu2Si2, is consistent with a stronger super-exchange in the …

Reconstructed Fermi surface and quantum oscillation of doped resonating valence bond state with incommensurate charge order in underdoped cuprates

Recent experiments have revealed incommensurate charge density wave (CDW) in the pseudogap regime in underdoped cuprates, e.g. YBa$_2$Cu$_3$O$_{6+δ}$ and HgBa$_2$CuO$_{4+δ}$. However, its relationship with the pseudogap is still controversial. In this work, we take a phenomenological synthesis of the doped resonating valence bond (RVB) state and the CDW order. Starting from the Yang-Rice-Zhang Green's function ansatz for the doped RVB state [Phys. Rev. B {\bf 73}, 174501 (2006)], in which the Fermi surface is partially truncated into four nodal hole-like Fermi pockets by the antinodal RVB gap,…

Hidden Charge 2e Boson: Experimental Consequences for Doped Mott Insulators

We show here that many of the normal state properties of the cuprates can result from the new charge 2e bosonic field which we have recently (Phys. Rev. Lett. {\bf 99}, 46404 (2007) and Phys. Rev. B 77, 014512 (2008)) shown to exist in the exact low-energy theory of a doped Mott insulator. In particular, the 1) mid-infrared band including the non-vanishing of the restricted f-sum rule in the Mott insulator, 2) the $T^2$ contribution to the thermal conductivity, 3) the pseudogap, 4) the bifurcation of the electron spectrum below the chemical potential as recently seen in angle-resolved photoemi…

Superconducting and excitonic quantum phase transitions in doped systems with Dirac electrons

Material systems with Dirac electrons on a bipartite planar lattice and possessing superconducting and excitonic interactions are investigated both in the half-filling and doped regimes at zero temperature. Excitonic pairing is the analog of chiral symmetry breaking of relativistic fermion theories and produces an insulating gap in the electronic spectrum. Condensed matter systems with such competing interactions display phenomena that are analogous to the onset of the chiral condensate and of color superconductivity in dense quark matter. Evaluation of the free-energy (effective potential) al…

Continuous transition from a Landau quasiparticle to a neutral spinon

We examine a wavefunction ansatz in which a doped hole can experience a quantum transition from a charge $+e$ Landau quasiparticle to a neutral spinon as a function of the underlying spin-spin correlation. As shown variationally, such a wavefunction accurately captures all the essential features revealed by exact diagonalization and density matrix renormalization group simulations in a two-leg $t$-$J$ ladder. Hence its analytic form can provide an explicit understanding of the mechanism for the unconventional ground state. The transition in the phase diagram is accompanied by a change of the h…

掺杂诱导的量子反常霍尔晶体与拓扑域墙

Doping-induced Quantum Anomalous Hall Crystals and Topological Domain Walls

研究掺杂对TMD莫尔超晶格中ν=1量子反常霍尔绝缘体的影响，发现掺杂可生成量子反常霍尔晶体和拓扑域墙，其中包含skyrmion自旋纹理和chiral局域模式。

黎曼邂逅戈德斯通：磁振子在量子霍尔斯格明子晶体上的散射可探测对称性破缺与拓扑的相互作用

Riemann meets Goldstone: magnon scattering off quantum Hall skyrmion crystals probes interplay of symmetry breaking and topology

本研究构建了夹在铁磁体间的斯格明子晶体散射模型，结合解析与数值方法发现磁振子输运兼具低能Goldstone模式峰与高能演生朗道能级带状特征，可作为量子霍尔斯格明子晶体相的直接探测信号，适用于石墨烯异质结等体系。