Switchable Multiple Spin States in the Kondo description of Doped Molecular Magnets

Rajyavardhan Ray,Sanjeev Kumar

doi:10.1038/srep42255

Abstract

We show that introducing electrons in magnetic clusters and molecular magnets lead to rich phase diagrams with a variety of low-spin and high-spin states allowing for multiple switchability. The analysis is carried out for a quantum spin-fermion model using the exact diagonalization, and the cluster mean-field approach. The model is relevant for a number of molecular magnets with triangular motifs consisting of transition metal ions such as Cr, Cu and V. Re-entrant spin-state behavior and chirality on-off transitions exist over a wide parameter regime. A subtle competition among geometrical frustration effects, electron itinerancy, and Kondo coupling at the molecular level is highlighted. Our results demonstrate that electron doping provides a viable mean to tame the magnetic properties of molecular magnets towards potential technological applications.

Highlights

Molecular Magnets (MMs) comprising of exchange-coupled cluster of transition metal ions have emerged as potential candidates for technological applications in recent years[1,2,3]
We begin with a model for a triangular single-molecule magnetss (SMMs) cluster doped with a single electron
The net magnetic moment is zero, the ground state corresponds to the symmetry-broken mean field which acts like an external magnetic field coupled to the total spin

Summary

Introduction

Molecular Magnets (MMs) comprising of exchange-coupled cluster of transition metal ions have emerged as potential candidates for technological applications in recent years[1,2,3]. In order to clearly understand the origin of the spin-state switching driven by Kondo coupling, we compute the contribution of each term in the Hamiltonian to the total ground state energy. For an undoped cluster applying large external magnetic field, B, leads to a high-spin ground state, HS, characterized by Stot = 3/2 and Dij = 1/4 =Fij (∀ij).

Results

Conclusion