Modelling magnetic anisotropy of single-chain magnets in |d/J| ≥ 1 regime. (17th November 2017)

• Record Type: Journal Article
• Authors: Haldar, Sumit; Raghunathan, Rajamani; Sutter, Jean-Pascal; Ramasesha, S.
• Is Part Of: Molecular physics. Volume 115:Number 21/22(2017)
• Page Start: 2849
• Page End: 2859
• Publication Date: 2017-11-17
• Subjects: Single-chain magnets -- anisotropy -- model Hamiltonian; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2017.1346832
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: Single-molecule magnets (SMMs) with single-ion anisotropies comparable to exchange interactions J between spins have recently been synthesised. Here, we provide theoretical insights into the magnetism of such systems. We study spin chains with site-spins, s = 1, 3/2 and 2 and strength of on-site anisotropy comparable to the exchange constants between the spins. We find that large on-site anisotropies lead to crossing of the states with different M S values in the same spin manifold to which they belong in the absence of anisotropy. When on-site anisotropy is increased further, we also find that the M S states of the higher energy spin states descend below the M S states of the ground spin manifold. Giant spin in this limit is no longer conserved and describing the axial and rhombic anisotropies of the molecule, D M and E M, respectively, is not possible. However, the giant spin of the low-lying large M S states is very nearly an integer and, using this spin value, it is possible to construct an effective spin-Hamiltonian and compute the molecular magnetic anisotropy constants D M and E M . We report effect of finite sizes, rotations of site anisotropies and chain dimerisation on the effective anisotropy of the spin chains. Abstract :