Spin densities in organic magnets

Spin densities in organic magnets

Introduction. In our work we are focused in the development of new types of triangular spin networks employing highly isotropic organic radical spins. By rational designing of organic tri-radicals, an equilateral triangle of S = 1/2 spins can be constructed. Since the anisotropy of the g-factor of these nitroxide-based compounds is less than 0.5 %, the electron spins are fully isotropic. These would be the best realizations of fluctuating spin system, which will show novel collective phenomena. In this context we have succeeded in synthesizing the new compounds F4BIPBNN , which forms a distorted Honeycomb lattice. The magnetic and thermal properties were examined in magnetic fields and the magnetic field versus temperature phase diagram is determined (1)

The goal of the present TFM is double. On one side we are interested in the exploration of the magnetic phase diagram of F4BIPBNN by the determination the magnetic structure of below 0.4K. For this goal we will collect data of neutron diffraction in deuterated single crystals of F4BIPBNN and, as a first step, we will model the different magnetic structures allowed by the symmetry in the organic radical. On the other hand, we will determine with polarized neutrons diffraction the spin density in the radical. The real experimental spin density determination at F4BIPBNN will help us to validate the MO and Broken Symmetry calculations and to have another independent experimental estimation of the intra and inter molecular interactions. However, previously to the experiment, we will simulate the real experiments taken into account the theoretical spin density obtained by DFT calculations.

Concepts that will be acquired:

  • Single crystal diffraction
  • Group theory and magnetic crystallography
  • Neutron scattering

Task to be developped:

  • Bibliography on the subject.
  • magnetic structure simulation
  • spin density modelization

More information contact with Javier Campo

(1) Naoki Amaya, et al Journal of the Physical Society of Japan 86, 074706 (2017)