We assess the ground-state phase diagram of the Heisenberg model on the Kagome lattice by employing Gutzwiller-projected fermionic wave functions. Within this framework, different states can be represented, defined by distinct unprojected fermionic Hamiltonians that include hopping and pairing terms, as well as a coupling to local Zeeman fields to generate magnetic order. For , the so-called U(1) Dirac state, in which only hopping is present (such as to generate a -flux in the hexagons), has been shown to accurately describe the exact ground state [Y. Iqbal, F. Becca, S. Sorella, and D. Poilblanc, Phys. Rev. B87, 060405(R) (2013)10.1103/PhysRevB.87.060405; Y.-C. He, M. P. Zaletel, M. Oshikawa, and F. Pollmann, Phys. Rev. X7, 031020 (2017)10.1103/PhysRevX.7.031020.]. Here we show that its accuracy improves in the presence of a small antiferromagnetic superexchange , leading to a finite region where the gapless spin liquid is stable; then, for , a first-order transition to a magnetic phase with pitch vector is detected by allowing magnetic order within the fermionic Hamiltonian. Instead, for small ferromagnetic values of , the situation is more contradictory. While the U(1) Dirac state remains stable against several perturbations in the fermionic part (i.e., dimerization patterns or chiral terms), its accuracy clearly deteriorates on small systems, most notably on 36 sites where exact diagonalization is possible. Then, on increasing the ratio , a magnetically ordered state with periodicity eventually overcomes the U(1) Dirac spin liquid. Within the ferromagnetic regime, evidence is shown in favor of a first-order transition at .

Gutzwiller projected states for the Heisenberg model on the Kagome lattice: Achievements and pitfalls

Parola A.;
2021-01-01

Abstract

We assess the ground-state phase diagram of the Heisenberg model on the Kagome lattice by employing Gutzwiller-projected fermionic wave functions. Within this framework, different states can be represented, defined by distinct unprojected fermionic Hamiltonians that include hopping and pairing terms, as well as a coupling to local Zeeman fields to generate magnetic order. For , the so-called U(1) Dirac state, in which only hopping is present (such as to generate a -flux in the hexagons), has been shown to accurately describe the exact ground state [Y. Iqbal, F. Becca, S. Sorella, and D. Poilblanc, Phys. Rev. B87, 060405(R) (2013)10.1103/PhysRevB.87.060405; Y.-C. He, M. P. Zaletel, M. Oshikawa, and F. Pollmann, Phys. Rev. X7, 031020 (2017)10.1103/PhysRevX.7.031020.]. Here we show that its accuracy improves in the presence of a small antiferromagnetic superexchange , leading to a finite region where the gapless spin liquid is stable; then, for , a first-order transition to a magnetic phase with pitch vector is detected by allowing magnetic order within the fermionic Hamiltonian. Instead, for small ferromagnetic values of , the situation is more contradictory. While the U(1) Dirac state remains stable against several perturbations in the fermionic part (i.e., dimerization patterns or chiral terms), its accuracy clearly deteriorates on small systems, most notably on 36 sites where exact diagonalization is possible. Then, on increasing the ratio , a magnetically ordered state with periodicity eventually overcomes the U(1) Dirac spin liquid. Within the ferromagnetic regime, evidence is shown in favor of a first-order transition at .
2021
Iqbal, Y.; Ferrari, F.; Chauhan, A.; Parola, A.; Poilblanc, D.; Becca, F.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2119145
 Attenzione

L'Ateneo sottopone a validazione solo i file PDF allegati

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 15
  • ???jsp.display-item.citation.isi??? 15
social impact