Effects of Single-site Anisotropy on Mixed Diamond Chains with Spins 1 and 1/2

TL;DR

This paper studies how single-site anisotropy influences the ground states and finite-temperature properties of mixed spin-1 and spin-1/2 diamond chains, revealing various magnetic phases and their thermal behaviors.

Contribution

It provides a detailed analysis of anisotropy effects on phase diagrams and thermodynamic properties in mixed-spin diamond chains, highlighting new phase distinctions and temperature sensitivities.

Findings

Ground state can be nonmagnetic or paramagnetic depending on anisotropy.

Identifies phases like Néel, Haldane, and large-D with infinite spin clusters.

Finite-temperature susceptibilities and entropy are highly anisotropy-dependent.

Abstract

Effects of single-site anisotropy on mixed diamond chains with spins 1 and 1/2 are investigated in the ground states and at finite temperatures. There are phases where the ground state is a spin cluster solid, i.e., an array of uncorrelated spin-1 clusters separated by singlet dimers. The ground state is nonmagnetic for the easy-plane anisotropy, while it is paramagnetic for the easy-axis anisotropy. Also, there are the N\'eel, Haldane, and large-$D$ phases, where the ground state is a single spin cluster of infinite size and the system is equivalent to the spin-1 Heisenberg chain with alternating anisotropy. The longitudinal and transverse susceptibilities and entropy are calculated at finite temperatures in the spin-cluster-solid phases. Their low-temperature behaviors are sensitive to anisotropy.