Theoretical Investigations of Electronic Structure and Magnetic and Optical Properties of Transition-Metal Dinuclear Molecules

Abstract

In this work, we have reported the electronic structure, spin state, and optical properties of a new class of transition-metal (TM) dinuclear molecules (TM = Cr, Mn, Fe, Co, and Ni). The stability of these molecules has been analyzed from the vibration spectra obtained by using density functional theory (DFT) calculations. The ground-state spin configuration of the tetra-coordinated TM atom in each molecule has been predicted from the relative total energy differences in different spin states of the molecule. The DFT + U method has been used to investigate the precise ground-state spin configuration of each molecule. We further performed time-dependent DFT calculations to study the optical properties of these molecules. The planar geometric structure remains intact in most of the cases; hence, these molecules are expected to be well adsorbed and self-assembled on metal substrates. In addition, the optical characterization of these molecules indicates that the absorption spectra have a large peak in the blue-light wavelength range; therefore, it could be suitable for advanced optoelectronic device applications. Our work promotes further computational and experimental studies on TM dinuclear molecules in the field of molecular spintronics and optoelectronics.

Understanding and tuning of spinterface for chemisorbed Ni-dinuclear quinonoid on Co(001) substrate

“…This technique has been proven to be very promising to achieve the precise spin state of molecules and low-dimensional magnetic systems [22][23][24][25]. The on-site Coulomb and exchange parameters U and J for the partially filled d orbitals of Ni atom were chosen to be 4.0 and 1.0 eV, respectively [17]. A sufficiently large planewave cutoff energy of 500 eV was used.…”

“…This can be realize from the square planer co-ordination of Ni +2 atom in the molecule. Comparatively shorter Ni-ligand bond lengths introduce a strong ligand field effect on Ni 3d-orbitals that forces all eight d electrons in Ni atom to occupy four lower energy levels, that leads to the paramagnetic low spin state (S = 0) of the molecule [17]. However, the magnetic structure of the molecule has been changed upon adsorption on Co substrate.…”

“…In search of new materials to address the magnetic switching at a molecular level, we have recently observed that the NiQ molecule undergoes a substrate-induced spin-state switching through strong ferromagnetic spin interactions with Co(001) substrate [16]. Also, the magnetic properties of a series of spin-bearing TM-dinuclear molecules in which the quinonoid molecules link two TM atoms have recently been investigated [17]. However, despite technological applications, it is essential to understand molecular adsorption and its interactions with the magnetic substrates.…”