Fermi liquid of spinons in quasi-one-dimensional antiferromagnets

B. Lake, Anup Kumar Bera, Fabian H. L. Eßler +6 more

Oleg A. Starykh, Leon Balents

P. Lecheminant

Aleksandr I. Smirnov

We report the experimental observation of a shift of the boundaries of the spinon continuum caused by a Fermiliquid interaction of spinons in the spin-liquid S 1a2 chaintype antiferromagnet K 2 CuSO 4 Br 2 .The parameter of spinon interaction, which determines the probability of backscattering, is found.In the pseudospin S 1a2 chain-type strongly anisotropic antiferromagnet Cs 2 CoCl 4 , a shift in the magnetic resonance frequency is detected during the crossover from the disordered spin regime to the state of correlated XXZ-type spin chains at a temperature above the emergence of longrange antiferromagnetic order.This resonance shift is explained on the basis of the spectrum of spin excitations in correlated XXZ chains and corresponds to theoretical simulation of the spectra of spinon-type magnetic fluctuations in XXZ chains [P.Laurell et al.Phys.Rev. Lett.127 037201 (2021)].

Anna Minguzzi

Ryan V. Mishmash, Amir M-Aghaei, Bela Bauer +1 more

The search for exotic quantum spin liquid states in simple yet realistic spin models remains a central challenge in the field of frustrated quantum magnetism. Here we consider the canonical nearest-neighbor kagome Heisenberg antiferromagnet restricted to a quasi-one-dimensional strip consisting entirely of corner-sharing triangles. Using large-scale density matrix renormalization group calculations, we identify in this model an extended gapless quantum phase characterized by central charge c = 2 and power-law decaying spin and bond-energy correlations which oscillate at tunably incommensurate wave vectors. We argue that this intriguing spin liquid phase can be understood as a marginal instability of a two-band spinon Fermi surface coupled to an emergent U(1) gauge field, an interpretation which we substantiate via bosonization analysis and Monte Carlo calculations on model Gutzwiller variational wave functions. Our results represent one of the first numerical demonstrations of emergent fermionic spinons in a simple SU(2) invariant nearest-neighbor Heisenberg model beyond the strictly one-dimensional (Bethe chain) limit.