Parity dependent phase diagrams in spin-cluster two-leg ladders

Abstract

Motivated by the recent experiment on K2Cu3O (SO4) 3 , an edge-shared tetrahedral spin-cluster compound [M. Fujihala et al., Phys. Rev. Lett. 120, 077201 (2018)], we investigate two-leg spin-cluster ladders with the plaquette number np in each cluster up to six by the density-matrix renormalization group method. We find that the phase diagrams of such ladders strongly depend on the parity of np. For even np, the phase diagrams have two phases, one is the Haldane phase, and the other is the cluster rung-singlet phase. For odd np, there are four phases, which are a cluster-singlet phase, a cluster rung-singlet phase, a Haldane phase and an even Haldane phase. Moreover, in the latter case the region of the Haldane phase increases while that of the cluster-singlet phase and the even Haldane phase shrinks as np increases. We thus conjecture that in the large np limit, the phase diagrams will become independent of np. By analysing the ground-state energy and entanglement entropy we obtain the order of the phase transitions. In particular, for np = 1 there is no phase transition between the even Haldane phase and the cluster rung-singlet phase while for other odd np there is a first-order phase transition. Our work provides comprehensive phase diagrams for these cluster-based models and may be helpful to understand experiments on related materials.

Real-space parallel density matrix renormalization group with adaptive boundaries*

“…[44] This kind of spin-cluster chain (SCC) has attracted recent researches about quantum phase transitions and magnetic properties, both theoretically and experimentally. [45][46][47] The quasi-onedimensional K 2 Cu 3 O(SO 4 ) 3 material can be described by the Hamiltonian [44]…”

Synthetic gauge field and chiral physics on two-leg superconducting circuits

“…In a recent breakthrough experiment, a two-leg superconducting circuits with 24 transmon qubits has been reported and the singleand double-excitation dynamics has been observed [21]. This experiment opens a new route to explore exotic many-body physics [22][23][24][25][26][27][28][29][30][31], which can be induced by the competition between interleg and intraleg hoppings and strong interaction of photons on superconducting circuits.…”