Tuning the magnetic ground state of a novel tetranuclear Nickel(II) molecular complex by high magnetic fields

TL;DR

This study investigates a novel tetranuclear Nickel(II) complex, demonstrating how high magnetic fields can tune its magnetic ground state from nonmagnetic to magnetic through spin level crossing.

Contribution

It provides detailed ESR and magnetization analysis of a new Ni4 complex, revealing magnetic ground state tuning via high magnetic fields, which was not previously demonstrated in such complexes.

Findings

Ground state switches from nonmagnetic to magnetic at ~25 T

ESR analysis yields key spin Hamiltonian parameters

Magnetic field influences the energy spectrum significantly

Abstract

Electron spin resonance and magnetization data in magnetic fields up to 55 T of a novel multicenter paramagnetic molecular complex [L_2Ni_4(N_3)(O_2C Ada)_4](Cl O_4) are reported. In this compound, four Ni centers each having a spin S = 1 are coupled in a single molecule via bridging ligands (including a \mu_4-azide) which provide paths for magnetic exchange. Analysis of the frequency and temperature dependence of the ESR signals yields the relevant parameters of the spin Hamiltonian, in particular the single ion anisotropy gap and the g factor, which enables the calculation of the complex energy spectrum of the spin states in a magnetic field. The experimental results give compelling evidence for tuning the ground state of the molecule by magnetic field from a nonmagnetic state at small fields to a magnetic one in strong fields owing to the spin level crossing at a field of ~25 T.