Физика Низких Температур: Том 47, Выпуск 6 (Июнь 2021), c. 477-482 ( к оглавлению , назад )
Quantum phase transitions in frustrated 1D Heisenberg spin systems
V. O. Cheranovskii1, V. V. Slavin2, and D. J. Klein3
1V. N. Karazin Kharkiv National University, Kharkiv 61022, Ukraine
2B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine Kharkiv 61103, Ukraine
3Texas A&M University at Galveston, Galveston, TX, USA
Received February 8, 2021, published online April 26, 2021
A class of frustrated one-dimensional periodic Heisenberg spin systems formed either by triangular unit cells with spin 1/2 or by composite unit cells formed by two different structural units, triangles and small linear segments formed by an odd number of spin-1/2 is investigated. Based on perturbative processing and numerical calculations of the density matrix renormalization group method, the gapless character of the exact energy spectrum of excitation for these systems was found. Their instability with respect to regular (Peierls) oscillations of interactions between structural units is demonstrated. The corresponding critical exponents for the energies of the ground state are estimated numerically. For some frustrated systems, a quantum phase transition associated with the spin symmetry of the ground state, caused by frustration, has been discovered.
Key words: Heisenberg spin Hamiltonian, frustrated one-dimensional spin systems, quantum phase transitions.