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Grossman O, Berg E. Robust Fermi-Liquid Instabilities in Sign Problem-Free Models. PHYSICAL REVIEW LETTERS 2023; 131:056501. [PMID: 37595239 DOI: 10.1103/physrevlett.131.056501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/19/2023] [Accepted: 06/20/2023] [Indexed: 08/20/2023]
Abstract
Determinant quantum Monte Carlo (DQMC) is a powerful numerical technique to study many-body fermionic systems. In recent years, several classes of sign-free (SF) models have been discovered, where the notorious sign problem can be circumvented. However, it is not clear what the inherent physical characteristics and limitations of SF models are. In particular, which zero-temperature quantum phases of matter are accessible within such models, and which are fundamentally inaccessible? Here, we show that a model belonging to any of the known SF classes within DQMC cannot have a stable Fermi-liquid ground state in spatial dimension d≥2, unless the antiunitary symmetry that prevents the sign problem is spontaneously broken (for which there are currently no known examples in SF models). For SF models belonging to one of the symmetry classes (where the absence of the sign problem follows from a combination of nonunitary symmetries of the fermionic action), any putative Fermi liquid fixed point generically includes an attractive Cooper-like interaction that destabilizes it. In the recently discovered lower-symmetry classes of SF models, the Fermi surface (FS) is generically unstable even at the level of the quadratic action. Our results suggest a fundamental link between Fermi liquids and the fermion sign problem. Interestingly, our results do not rule out a non-Fermi-liquid ground state with a FS in a sign-free model.
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Affiliation(s)
- Ori Grossman
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Erez Berg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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2
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Ghazaryan A, Holder T, Serbyn M, Berg E. Unconventional Superconductivity in Systems with Annular Fermi Surfaces: Application to Rhombohedral Trilayer Graphene. PHYSICAL REVIEW LETTERS 2021; 127:247001. [PMID: 34951779 DOI: 10.1103/physrevlett.127.247001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/12/2021] [Indexed: 06/14/2023]
Abstract
We show that in a two-dimensional electron gas with an annular Fermi surface, long-range Coulomb interactions can lead to unconventional superconductivity by the Kohn-Luttinger mechanism. Superconductivity is strongly enhanced when the inner and outer Fermi surfaces are close to each other. The most prevalent state has chiral p-wave symmetry, but d-wave and extended s-wave pairing are also possible. We discuss these results in the context of rhombohedral trilayer graphene, where superconductivity was recently discovered in regimes where the normal state has an annular Fermi surface. Using realistic parameters, our mechanism can account for the order of magnitude of T_{c}, as well as its trends as a function of electron density and perpendicular displacement field. Moreover, it naturally explains some of the outstanding puzzles in this material, that include the weak temperature dependence of the resistivity above T_{c}, and the proximity of spin singlet superconductivity to the ferromagnetic phase.
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Affiliation(s)
| | - Tobias Holder
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Maksym Serbyn
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Erez Berg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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3
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Park JW, Cho GY, Lee J, Yeom HW. Emergent honeycomb network of topological excitations in correlated charge density wave. Nat Commun 2019; 10:4038. [PMID: 31492870 PMCID: PMC6731227 DOI: 10.1038/s41467-019-11981-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 08/14/2019] [Indexed: 11/09/2022] Open
Abstract
When two periodic potentials compete in materials, one may adopt the other, which straightforwardly generates topological defects. Of particular interest are domain walls in charge-, dipole-, and spin-ordered systems, which govern macroscopic properties and important functionality. However, detailed atomic and electronic structures of domain walls have often been uncertain and the microscopic mechanism of their functionality has been elusive. Here, we clarify the complete atomic and electronic structures of the domain wall network, a honeycomb network connected by Z3 vortices, in the nearly commensurate Mott charge-density wave (CDW) phase of 1T-TaS2. Scanning tunneling microscopy resolves characteristic charge orders within domain walls and their vortices. Density functional theory calculations disclose their unique atomic relaxations and the metallic in-gap states confined tightly therein. A generic theory is constructed, which connects this emergent honeycomb network of conducting electrons to the enhanced superconductivity.
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Affiliation(s)
- Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Gil Young Cho
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Jinwon Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea.
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea.
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Hsu YT, Vaezi A, Fischer MH, Kim EA. Topological superconductivity in monolayer transition metal dichalcogenides. Nat Commun 2017; 8:14985. [PMID: 28397804 PMCID: PMC5394266 DOI: 10.1038/ncomms14985] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 02/20/2017] [Indexed: 12/23/2022] Open
Abstract
Theoretically, it has been known that breaking spin degeneracy and effectively realizing spinless fermions is a promising path to topological superconductors. Yet, topological superconductors are rare to date. Here we propose to realize spinless fermions by splitting the spin degeneracy in momentum space. Specifically, we identify monolayer hole-doped transition metal dichalcogenide (TMD)s as candidates for topological superconductors out of such momentum-space-split spinless fermions. Although electron-doped TMDs have recently been found superconducting, the observed superconductivity is unlikely topological because of the near spin degeneracy. Meanwhile, hole-doped TMDs with momentum-space-split spinless fermions remain unexplored. Employing a renormalization group analysis, we propose that the unusual spin-valley locking in hole-doped TMDs together with repulsive interactions selectively favours two topological superconducting states: interpocket paired state with Chern number 2 and intrapocket paired state with finite pair momentum. A confirmation of our predictions will open up possibilities for manipulating topological superconductors on the device-friendly platform of monolayer TMDs.
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Affiliation(s)
- Yi-Ting Hsu
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Abolhassan Vaezi
- Department of Physics, Stanford University, Stanford, California 94305-4060, USA
| | - Mark H. Fischer
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eun-Ah Kim
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
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Chen X, LeBlanc JPF, Gull E. Superconducting fluctuations in the normal state of the two-dimensional Hubbard model. PHYSICAL REVIEW LETTERS 2015; 115:116402. [PMID: 26406843 DOI: 10.1103/physrevlett.115.116402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Indexed: 06/05/2023]
Abstract
We compute the two-particle quantities relevant for superconducting correlations in the two-dimensional Hubbard model within the dynamical cluster approximation. In the normal state we identify the parameter regime in density, interaction, and second-nearest-neighbor hopping strength that maximizes the d_{x^{2}-y^{2}} superconducting transition temperature. We find in all cases that the optimal transition temperature occurs at intermediate coupling strength, and is suppressed at strong and weak interaction strengths. Similarly, superconducting fluctuations are strongest at intermediate doping and suppressed towards large doping and half filling. We find a change in sign of the vertex contributions to d_{xy} superconductivity from repulsive near half filling to attractive at large doping. p-wave superconductivity is not found at the parameters we study, and s-wave contributions are always repulsive. For negative second-nearest-neighbor hopping the optimal transition temperature shifts towards the electron-doped side in opposition to the van Hove singularity, which moves towards hole doping. We surmise that an increase of the local interaction of the electron-doped compounds would increase T_{c}.
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Affiliation(s)
- Xi Chen
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - J P F LeBlanc
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Emanuel Gull
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
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She JH, Bishop AR. RKKY interaction and intrinsic frustration in non-Fermi-liquid metals. PHYSICAL REVIEW LETTERS 2013; 111:017001. [PMID: 23863021 DOI: 10.1103/physrevlett.111.017001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 05/16/2013] [Indexed: 06/02/2023]
Abstract
We study the RKKY interaction in non-Fermi-liquid metals. We find that the RKKY interaction mediated by some non-Fermi-liquid metals can be of much longer range than for a Fermi liquid. The oscillatory nature of the RKKY interaction thus becomes more important in such non-Fermi liquids, and gives rise to enhanced frustration when the spins form a lattice. Frustration suppresses the magnetic ordering temperature of the lattice spin system. Furthermore, we find that the spin system with a longer range RKKY interaction can be described by the Brazovskii model, where the ordering wave vector lies on a higher dimensional manifold. Strong fluctuations in such a model lead to a first-order phase transition and/or glassy phase. This may explain some recent experiments where glassy behavior was observed in stoichiometric heavy fermion material close to a ferromagnetic quantum critical point.
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Affiliation(s)
- Jian-Huang She
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Koschorreck M, Pertot D, Vogt E, Fröhlich B, Feld M, Köhl M. Attractive and repulsive Fermi polarons in two dimensions. Nature 2012; 485:619-22. [DOI: 10.1038/nature11151] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 04/18/2012] [Indexed: 11/09/2022]
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Galitski V, Kim YB. Spin-triplet pairing instability of the spinon fermi surface in a U(1) spin liquid. PHYSICAL REVIEW LETTERS 2007; 99:266403. [PMID: 18233593 DOI: 10.1103/physrevlett.99.266403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Indexed: 05/25/2023]
Abstract
Recent experiments on the organic compound kappa-(ET)2Cu2(CN)3 have provided a promising example of a two-dimensional spin liquid state. This phase is described by a two-dimensional spinon Fermi sea coupled to a U(1) gauge field. We study Kohn-Luttinger-like pairing instabilities of the spinon Fermi surface due to singular interaction processes with twice-the-Fermi-momentum transfer. We find that under certain circumstances the pairing instability occurs in odd-orbital-angular momentum or spin-triplet channels. Implications to experiments are discussed.
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Affiliation(s)
- Victor Galitski
- Department of Physics and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA
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Saraga DS, Altshuler BL, Loss D, Westervelt RM. Coulomb scattering in a 2D interacting electron gas and production of EPR pairs. PHYSICAL REVIEW LETTERS 2004; 92:246803. [PMID: 15245120 DOI: 10.1103/physrevlett.92.246803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Indexed: 05/24/2023]
Abstract
We propose a setup to generate nonlocal spin Einstein-Podolsky-Rosen pairs via pair collisions in a 2D interacting electron gas, based on constructive two-particle interference in the spin-singlet channel at the pi/2 scattering angle. We calculate the scattering amplitude via the Bethe-Salpeter equation in the ladder approximation and small r(s) limit and find that the Fermi sea leads to a substantial renormalization of the bare scattering process. From the scattering length, we estimate the current of spin-entangled electrons and show that it is within experimental reach.
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Affiliation(s)
- D S Saraga
- Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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Ho PC, Hallock RB. Heat-capacity studies of (3)He in (3)He-(4)He mixture films and the coverage dependence of the two-dimensional (3)He Landau Fermi-liquid parameters. PHYSICAL REVIEW LETTERS 2001; 87:135301. [PMID: 11580601 DOI: 10.1103/physrevlett.87.135301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2001] [Indexed: 05/23/2023]
Abstract
The heat capacity of (3)He in (3)He-(4)He mixture films on a nuclepore substrate is reported over the temperature range 90<T<124 mK, for (3)He coverages between 0.05 and 1.4 bulk-density atomic layers, and a (4)He film thickness of 4.33 bulk-density atomic layers. A step structure appears in the specific heat as a function of (3)He coverage. Combining NMR and specific heat data for (3)He atoms on the same substrate and for the same (4)He coverage allows the two-dimensional Landau Fermi-liquid parameters F(A)(0) and F(S)(1) to be extracted as a function of (3)He coverage. We conclude that in the submonalayer (3)He coverage regime p-state pairing is favored.
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Affiliation(s)
- P C Ho
- Laboratory for Low Temperature Physics, Department of Physics, University of Massachusetts at Amherst, Amherst, Massachusetts 01003
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Avivi S, Mastai Y, Gedanken A. A New Fullerene-like Inorganic Compound Fabricated by the Sonolysis of an Aqueous Solution of TlCl3. J Am Chem Soc 2000. [DOI: 10.1021/ja993109j] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- S. Avivi
- Contribution from the Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel, 52900, and Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Y. Mastai
- Contribution from the Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel, 52900, and Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - A. Gedanken
- Contribution from the Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel, 52900, and Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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Hellberg CS, Manousakis E. Two-dimensional t-J model at low electron density. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:4639-4642. [PMID: 9981622 DOI: 10.1103/physrevb.52.4639] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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13
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Chubukov AV, Sokol A. Theory of p-wave pairing in a two-dimensional Fermi gas. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:678-681. [PMID: 10009340 DOI: 10.1103/physrevb.49.678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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14
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Khveshchenko DV, Hlubina R, Rice TM. Non-Fermi-liquid behavior in two dimensions due to long-ranged current-current interactions. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:10766-10776. [PMID: 10007376 DOI: 10.1103/physrevb.48.10766] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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