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2024
Birnkammer, S.; Knolle, J.; Knap, M. Signatures of domain-wall confinement in Raman spectroscopy of Ising spin chains Journal Article Phys. Rev. B 110, 134408 (2024). Abstract \| Links \| BibTeX \| Project(s): C6 @article{birnkammer_signatures_2024, title = {Signatures of domain-wall confinement in Raman spectroscopy of Ising spin chains}, author = {S. Birnkammer and J. Knolle and M. Knap}, doi = {10.1103/PhysRevB.110.134408}, year = {2024}, date = {2024-10-03}, urldate = {2024-10-03}, journal = {Phys. Rev. B}, volume = {110}, number = {13}, pages = {134408}, abstract = {Mesonic bound states of domain walls (DWs) can be stabilized in quasi-one-dimensional magnetic compounds. Here, we theoretically study the Raman light scattering response of a twisted Kitaev chain with tilted magnetic fields as a minimal model for confinement in CoNb2⁢O6. By both numerical matrix product states and few-DW variational states, we show that confinement-induced bound states directly manifest themselves as sharp peaks in the Raman response. Remarkably, by tuning the polarization of the incident light field, we demonstrate that the Raman response offers insights into the intrinsic symmetry of the bound-state wave function.}, keywords = {C6}, pubstate = {published}, tppubtype = {article} } Close Mesonic bound states of domain walls (DWs) can be stabilized in quasi-one-dimensional magnetic compounds. Here, we theoretically study the Raman light scattering response of a twisted Kitaev chain with tilted magnetic fields as a minimal model for confinement in CoNb2⁢O6. By both numerical matrix product states and few-DW variational states, we show that confinement-induced bound states directly manifest themselves as sharp peaks in the Raman response. Remarkably, by tuning the polarization of the incident light field, we demonstrate that the Raman response offers insights into the intrinsic symmetry of the bound-state wave function. Close doi:10.1103/PhysRevB.110.134408 Close
Jin, H. -K.; Kadow, W.; Knap, M.; Knolle, J. Kinetic ferromagnetism and topological magnons of the hole-doped Kitaev spin liquid Journal Article npj Quantum Mater. 9, 65 (2024). Abstract \| Links \| BibTeX \| Project(s): C6 @article{jin_kinetic_2024, title = {Kinetic ferromagnetism and topological magnons of the hole-doped Kitaev spin liquid}, author = {H. -K. Jin and W. Kadow and M. Knap and J. Knolle}, doi = {10.1038/s41535-024-00678-8}, year = {2024}, date = {2024-09-04}, urldate = {2024-09-01}, journal = {npj Quantum Mater.}, volume = {9}, number = {1}, pages = {65}, abstract = {We study the effect of hole doping on the Kitaev spin liquid (KSL) and find that for ferromagnetic (FM) Kitaev exchange K the system is very susceptible to the formation of a FM spin polarization. Through density matrix renormalization group simulations on finite systems, we uncover that the introduction of a single hole, corresponding to ≈1% hole doping for the system size we consider, with a hopping strength of just t textasciitilde 0.28K is enough to disrupt fractionalization and polarize the spins in the [001] direction due to an order-by-disorder mechanism. Taking into account a material relevant FM anisotropic exchange Γ drives the polarization towards the [111] direction via a transition into a topological FM state with chiral magnon excitations. We develop a parton mean-field theory incorporating fermionic holons and bosonic magnons, which accounts for the doping induced FM phases and topological magnon excitations. We discuss experimental implications for Kitaev candidate materials.}, keywords = {C6}, pubstate = {published}, tppubtype = {article} } Close We study the effect of hole doping on the Kitaev spin liquid (KSL) and find that for ferromagnetic (FM) Kitaev exchange K the system is very susceptible to the formation of a FM spin polarization. Through density matrix renormalization group simulations on finite systems, we uncover that the introduction of a single hole, corresponding to ≈1% hole doping for the system size we consider, with a hopping strength of just t textasciitilde 0.28K is enough to disrupt fractionalization and polarize the spins in the [001] direction due to an order-by-disorder mechanism. Taking into account a material relevant FM anisotropic exchange Γ drives the polarization towards the [111] direction via a transition into a topological FM state with chiral magnon excitations. We develop a parton mean-field theory incorporating fermionic holons and bosonic magnons, which accounts for the doping induced FM phases and topological magnon excitations. We discuss experimental implications for Kitaev candidate materials. Close doi:10.1038/s41535-024-00678-8 Close
Das, P.; Leeb, V.; Knolle, J.; Knap, M. Realizing altermagnetism in fermi-hubbard models with ultracold atoms Journal Article Phys. Rev. Lett. 132, 263402 (2024). Abstract \| Links \| BibTeX \| Project(s): C6 @article{das_realizing_2024, title = {Realizing altermagnetism in fermi-hubbard models with ultracold atoms}, author = {P. Das and V. Leeb and J. Knolle and M. Knap}, doi = {10.1103/PhysRevLett.132.263402}, year = {2024}, date = {2024-06-26}, urldate = {2024-06-01}, journal = {Phys. Rev. Lett.}, volume = {132}, number = {26}, pages = {263402}, abstract = {Altermagnetism represents a type of collinear magnetism, that is in some aspects distinct from ferromagnetism and from conventional antiferromagnetism. In contrast to the latter, sublattices of opposite spin are related by spatial rotations and not only by translations and inversions. As a result, altermagnets have spin-split bands leading to unique experimental signatures. Here, we show theoretically how a 𝑑-wave altermagnetic phase can be realized with ultracold fermionic atoms in optical lattices. We propose an altermagnetic Hubbard model with anisotropic next-nearest neighbor hopping and obtain the Hartree-Fock phase diagram. The altermagnetic phase separates in a metallic and an insulating phase and is robust over a large parameter regime. We show that one of the defining characteristics of altermagnetism, the anisotropic spin transport, can be probed with trap-expansion experiments.}, keywords = {C6}, pubstate = {published}, tppubtype = {article} } Close Altermagnetism represents a type of collinear magnetism, that is in some aspects distinct from ferromagnetism and from conventional antiferromagnetism. In contrast to the latter, sublattices of opposite spin are related by spatial rotations and not only by translations and inversions. As a result, altermagnets have spin-split bands leading to unique experimental signatures. Here, we show theoretically how a 𝑑-wave altermagnetic phase can be realized with ultracold fermionic atoms in optical lattices. We propose an altermagnetic Hubbard model with anisotropic next-nearest neighbor hopping and obtain the Hartree-Fock phase diagram. The altermagnetic phase separates in a metallic and an insulating phase and is robust over a large parameter regime. We show that one of the defining characteristics of altermagnetism, the anisotropic spin transport, can be probed with trap-expansion experiments. Close doi:10.1103/PhysRevLett.132.263402 Close
2023
Kadow, W.; Jin, H. -K.; Knolle, J.; Knap, M. Single-hole spectra of Kitaev spin liquids: From dynamical Nagaoka ferromagnetism to spin-hole fractionalization Journal Article npj Quantum Mater. 9, 32 (2023). Links \| BibTeX \| Project(s): C6 @article{kadow_single-hole_2023, title = {Single-hole spectra of Kitaev spin liquids: From dynamical Nagaoka ferromagnetism to spin-hole fractionalization}, author = {W. Kadow and H. -K. Jin and J. Knolle and M. Knap}, doi = {10.1038/s41535-024-00641-7}, year = {2023}, date = {2023-01-01}, urldate = {2023-01-01}, journal = {npj Quantum Mater.}, volume = {9}, pages = {32}, keywords = {C6}, pubstate = {published}, tppubtype = {article} } Close doi:10.1038/s41535-024-00641-7 Close	$Single-hole spectra of Kitaev spin liquids: From dynamical Nagaoka ferromagnetism to spin-hole fractionalization$