The ground state phase diagram of a spin S=1/2 XXZ Heisenberg chain with spatially modulated Dzyaloshinskii-Moriya (DM) interaction

is studied using the continuum-limit bosonization approach and density matrix renormalization group computations. It is shown that at  the effective continuum-limit bosonized theory of the model is given by the double frequency sine-Gordon model (DSG) where the frequencies i.e. the scaling dimensions of the two competing cosine perturbation terms depend on the effective anisotropy parameter . Exploring the ground state properties of the DSG model is show that the zero-temperature phase diagram contains the following four phases: (i) the ferromagnetic phase (FM) at  (ii) the gapless Luttinger-liquid (LL) phase at (iii) the gapped composite (C1) phase characterized by coexistence of the long-range-ordered (LRO) dimerization pattern  with the LRO alternating spin chirality pattern  at  and (iv) at at  the gapped composite (C2) phase characterized in addition to the coexisting spin dimerization and alternating chirality patterns, by the presence of LRO antiferromagnetic order. The transition from the LL to the C1 phase at  belongs to the Berezinskii-Kosterlitz-Thouless universality class, while the transition at  from C1 to C2 phase is of the Ising type.

Prof. George I. Japaridze received his MSc from the Tbilisi State University in 1975. Starting from 1976, he continuously works at the Andronikashvili Institute of Physics, where he received his PhD degree in 1983 and Doctor of Sciences degree in 1998. Currently he is the head of the Scientific Council of the Institute and Academician-Secretary of the Mathematics and Physics Department of the Georgian National Academy of Sciences. Scientific interests are connected with the physics of low-dimensional systems, including correlated electrons, spin systems, spintronics, theory of metal-insulator transitions, unconventional mechanisms of superconductivity and topological materials.