Yiming Wu

All Publications

• Intra-Unit-Cell Singlet Pairing Mediated by Altermagnetic Fluctuations. Physical review letters Wu, Y. M., Wang, Y., Fernandes, R. M. 2025; 135 (15): 156001

  Abstract

  We investigate the superconducting instabilities induced by altermagnetic fluctuations. Because of the nontrivial sublattice structure of the altermagnetic order, shorter-range and longer-range fluctuations favor qualitatively different types of pairing states. Specifically, while the latter stabilize a standard spin-triplet p-wave state, just like ferromagnetic fluctuations, the former leads to intra-unit-cell pairing, in which the Cooper pairs are formed by electrons from different sublattices. The symmetry of the intra-unit-cell gap function can be not only p-wave, but also spin-singlet s-wave and d-wave, depending on the shape of the Fermi surface. We also show that coexistence with altermagnetic order promotes intrinsic nontrivial topology, such as protected Bogoliubov Fermi surfaces and higher-order topological superconductivity. Our Letter establishes the key role played by sublattice degrees of freedom in altermagnetic-fluctuation mediated interactions.

  View details for DOI 10.1103/dlpb-gfct

  View details for PubMedID 41138087

• Possible Sliding Regimes in Twisted Bilayer WTe_{2}. Physical review letters Wu, Y. M., Murthy, C., Kivelson, S. A. 2024; 133 (24): 246501

  Abstract

  Inspired by the observation of increasingly one-dimensional (1D) behavior with decreasing temperature in small-angle twisted bilayers of WTe_{2} (tWTe_{2}), we theoretically explore the exotic sliding regimes that could be realized in tWTe_{2}. At zero displacement field, while hole-doped tWTe_{2} can be thought of as an array of weakly coupled conventional two-flavor 1D electron gases (1DEGs), the electron-doped regime is equivalent to coupled four-flavor 1DEGs, due to the presence of an additional "valley" degree of freedom. In the decoupled limit, the electron-doped system can thus realize phases with a range of interesting ordering tendencies, including 4k_{F} charge-density-wave and charge-4e superconductivity. Dimensional crossovers and cross-wire transport due to interwire couplings of various kinds are also discussed. We find that a sliding Luther-Emery liquid with small interwire couplings is probably most consistent with current experiments on hole-doped tWTe_{2}.

  View details for DOI 10.1103/PhysRevLett.133.246501

  View details for PubMedID 39750352

• Emergence of the Chern Supermetal and Pair-Density Wave through Higher-Order Van Hove Singularities in the Haldane-Hubbard Model. Physical review letters Castro, P., Shaffer, D., Wu, Y. M., Santos, L. H. 2023; 131 (2): 026601

  Abstract

  While advances in electronic band theory have brought to light new topological systems, understanding the interplay of band topology and electronic interactions remains a frontier question. In this work, we predict new interacting electronic orders emerging near higher-order Van Hove singularities present in the Chern bands of the Haldane model. We classify the nature of such singularities and employ unbiased renormalization group methods that unveil a complex landscape of electronic orders, which include ferromagnetism, density waves, and superconductivity. Importantly, we show that repulsive interactions can stabilize the long-sought pair-density-wave state and an exotic Chern supermetal, which is a new class of non-Fermi liquid with anomalous quantum Hall response. This framework opens a new path to explore unconventional electronic phases in two-dimensional chiral bands through the interplay of band topology and higher-order Van Hove singularities.

  View details for DOI 10.1103/PhysRevLett.131.026601

  View details for PubMedID 37505946

• Pair-Density-Wave and Chiral Superconductivity in Twisted Bilayer Transition Metal Dichalcogenides. Physical review letters Wu, Y. M., Wu, Z., Yao, H. 2023; 130 (12): 126001

  Abstract

  We theoretically explore possible orders induced by weak repulsive interactions in twisted bilayer transition metal dichalcogenides (e.g., WSe_{2}) in the presence of an out-of-plane electric field. Using renormalization group analysis, we show that superconductivity survives even with the conventional van Hove singularities. We find that topological chiral superconducting states with Chern number N=1, 2, 4 (namely, p+ip, d+id, and g+ig) appear over a large parameter region with a moiré filling factor around n=1. At some special values of applied electric field and in the presence of a weak out-of-plane Zeeman field, spin-polarized pair-density-wave (PDW) superconductivity can emerge. This spin-polarized PDW state can be probed by experiments such as spin-polarized STM measuring spin-resolved pairing gap and quasiparticle interference. Moreover, the spin-polarized PDW could lead to a spin-polarized superconducting diode effect.

  View details for DOI 10.1103/PhysRevLett.130.126001

  View details for PubMedID 37027848

• Pair Density Wave Order from Electron Repulsion. Physical review letters Wu, Y. M., Nosov, P. A., Patel, A. A., Raghu, S. 2023; 130 (2): 026001

  Abstract

  A pair density wave (PDW) is a superconductor whose order parameter is a periodic function of space, without an accompanying spatially uniform component. Since PDWs are not the outcome of a weak-coupling instability of a Fermi liquid, a generic pairing mechanism for PDW order has remained elusive. We describe and solve models having robust PDW phases. To access the intermediate coupling limit, we invoke large-N limits of Fermi liquids with repulsive BCS interactions that admit saddle point solutions. We show that the requirements for long-range PDW order are that the repulsive BCS couplings must be nonmonotonic in space and that their strength must exceed a threshold value. We obtain a phase diagram with both finite temperature transitions to PDW order and a T=0 quantum critical point, where non-Fermi liquid behavior occurs.

  View details for DOI 10.1103/PhysRevLett.130.026001

  View details for PubMedID 36706394