Magnetic properties of transition metal dimers probed by inelastic neutron scattering

Abstract

The physical characterisation and understanding of molecular magnetic materials is one of the most important steps towards the integration of such systems in hybrid spintronic devices. Amongst the many characterisation techniques employed in such a task, Inelastic Neutron Scattering (INS) stands as one of the most powerful and sensitive tools to investigate their spin dynamics. Herein, the magnetic properties and spin dynamics of two dinuclear complexes, namely [(M(hfacac)2)2(bpym)] (where M = Ni2+, Co2+, abbreviated in the following as Ni2, Co2) are reported. These are model systems that could constitute fundamental units of future spintronic devices. By exploiting the highly sensitive IN5 Cold INS spectrometer, we are able to gain a deep insight into the spin dynamics of Ni2 and to fully obtain the microscopic spin Hamiltonian parameters; while for Co2, a multitude of INS transitions are observed demonstrating the complexity of the magnetic properties of octahedral cobalt-based systems.

First-principles many-body models for electron transport through molecular nanomagnets

“…47, we find J = 3.3 meV, antiferromagnetic, and in good agreement with results from a recent inelastic neutron scattering study. 45 The zero-field splitting tensor D i is a full 3 × 3 matrix. By diagonalizing it we can determine the principal anisotropy axes and the values of the axial d i and rhombic e i zero-field splitting parameters.…”

“…We show the power of the method for a prototypical case, the {Ni 2 } molecule. 44,45 Transition metal dimers of this form have already been studied as test-beds for transport phenomena, such as Kondo effect or singlet-triplet switching by a bias voltage. 46 For {Ni 2 }-based junctions (see Fig.…”

Comprehensive Studies of Magnetic Transitions and Spin–Phonon Couplings in the Tetrahedral Cobalt Complex Co(AsPh3)2I2

“…Inelastic neutron scattering (INS) is a powerful method for probing magnetic energy levels and phonons in d and f complexes − with increasing uses recently. ,,,− INS, covering a variety of methods and spectrometers, has been reviewed. , As in FIRMS, finding a magnetic peak among phonon peaks in INS spectra is often a challenge. INS may directly reveal magnetic transitions, especially when few phonons are nearby. ,, When magnetic peaks overlap with phonons, variable-temperature (VT) or variable-field INS may be used to reveal the magnetic peaks.…”

Unravelling the Spin Dynamics of Molecular Nanomagnets with Four‐Dimensional Inelastic Neutron Scattering

“…Besides intra‐multiplet transitions due to anisotropy‐induced energy splittings, INS allows one to observe transitions between different total‐spin multiplets and to detect S‐mixing effects leading to the breakdown of the Giant‐Spin model , . For instance, antiferromagnetic (AF) rings have been fully characterized by this technique,, , , , together with many other MNMs . Moreover, the rich physics displayed by MNMs can be probed by INS, unravelling some of the above mentioned peculiar quantum phenomena, such as Néel‐vector tunneling,, frustration,, , , and finite‐size effects , .…”

“…[51,52] For instance, antiferromagnetic (AF) rings have been fully characterised by this technique, [13,22,28,53,54] together with many other MNMs. [55][56][57][58][59][60][61] Moreover, the rich physics displayed by MNMs can be probed by INS, unravelling some of the above mentioned peculiar quantum phenomena, such as Néel-vector tunnelling, [16,17] frustration, [8,10,11,[62][63][64][65] and finite-size effects. [14,66] Finally, INS has been employed to evidence the effect of pressure on the Mn12 anisotropy barrier [67] and to monitor its relaxation dynamics.…”