Details

Autor(en) / Beteiligte

• Sahoo, Shaon
• Dey, Dayasindhu
• Saha, Sudip Kumar
• Kumar, Manoranjan

Titel

Haldane and dimer phases in a frustrated spin chain: an exact groundstate and associated topological phase transition

Ist Teil von

• Journal of physics. Condensed matter, 2020-08, Vol.32 (33), p.335601

Ort / Verlag

England: IOP Publishing

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A Heisenberg spin-s chain with alternating ferromagnetic (FM) (−J1F<0) and antiferromagnetic (J1A>0) nearest-neighbor (NN) interactions, exhibits the dimer and spin-2s Haldane phases in the limits J1F/J1A→0 and J1F/J1A→∞ respectively. These two phases are understood to be topologically equivalent. Induction of the frustration through the next NN FM interaction (−J2F<0) produces a very rich quantum phase diagram. With frustration, the whole phase diagram is divided into a FM and a nonmagnetic (NM) phase. For s = 1/2, the full NM phase is seen to be of Haldane-dimer type, but for s > 1/2, a spiral phase comes between the FM and the Haldane-dimer phases. The study of a suitably defined string-order parameter and spin-gap at the phase boundary indicates that the Haldane-dimer and spiral phases have different topological characters. We also find that, along the J2F=12J1F line in the NM phase, an NN dimer state is the exact groundstate, provided J1A>JC=κJ1F where κ ⩽ s + h for applied magnetic field h. Without magnetic field, the position of JC is on the FM-NM phase boundary when s = 1/2, but for s > 1/2, the location of JC is on the phase separation line between the Haldane-dimer and spiral phases.