Unconventional Field-Induced Spin Gap in an S=1/2 Chiral Staggered Chain

Abstract

We investigate the low-temperature magnetic properties of the molecule-based chiral spin chain [Cu(pym)(H2O)4]SiF6·H2O (pym = pyrimidine). Electron-spin resonance, magnetometry and heat capacity measurements reveal the presence of staggered g tensors, a rich low-temperature excitation spectrum, a staggered susceptibility and a spin gap that opens on the application of a magnetic field. These phenomena are reminiscent of those previously observed in non-chiral staggered chains, which are explicable within the sine-Gordon quantum-field theory. In the present case, however, although the sine-Gordon model accounts well for the form of the temperature-dependence of the heat capacity, the size of the gap and its measured linear field dependence do not fit with the sine-Gordon theory as it stands. We propose that the differences arise due to additional terms in the Hamiltonian resulting from the chiral structure of [Cu(pym)(H2O)4]SiF6·H2O, particularly a uniform Dzyaloshinskii-Moriya coupling and a four-fold periodic staggered field.

Nonlinear soliton confinement in weakly coupled antiferromagnetic spin chains

“…This suggests that spinons can be viewed as quantum solitons [24] and therefore exhibit chirality, which was indeed confirmed by polarized neutron scattering [25]. Soliton and breather modes were identified in neutron-scattering [26,27] and electron-spin-resonance [28,29] experiments.…”

Magnetic ground state of the one-dimensional ferromagnetic chain compoundsM(NCS)2(thiourea)2(MCurley1, Scatena2, Williams3 et al. 2021Phys. Rev. MaterialsSelf Cite8130View full textAdd to dashboardCite

“…In terms of physically realising such systems, the use of organic ligands has proven highly effective in constructing crystal architectures that readily promote lowdimensional magnetic behaviour [12][13][14][15][16]. A selection of recently published materials showcase the ability to test the limits of the theoretical understanding of S = 1/2 and S = 1 chain materials [17][18][19]. To achieve quasi-onedimensional (Q1D) behaviour, the choice of intrachain bridging-ligand is a decisive one, as it ultimately determines the sign and strength of the intrachain exchange interaction (J).…”

Field-induced dimer orders in quantum spin chains

“…The experiment [16] on [Cu(pym)(H 2 O) 4 ]SiF 6 · H 2 O found that ESR peaks of this compound exhibit unconventional power-law dependence on the magnetic field. A part of this unconventional behavior is attributed to the chiral rotation and the complex dependence of the coupling constant on the magnetic field.…”

“…h 0 and h 2 are applied in the x and the y directions, respectively. The model used in Ref [16]. contains a weak XXZ interaction and the uniform DM interaction.…”