A Multiferroic Molecular Magnetic Qubit

TL;DR

This study uses density-functional methods to explore the spin-electric properties of a chiral Fe-based molecular cation, revealing multiple energetically competitive spin states and potential for external control as a molecular qubit.

Contribution

It demonstrates, through computational analysis, that this molecular system has multiple stable spin states and distinct electronic signatures, enhancing its potential as a controllable quantum bit.

Findings

Existence of energetically competitive high and low spin states.

Distinct core level broadening can indicate the preferred spin state.

Potential for external electric control of the spin states.

Abstract

The chiral $Fe_3O(NC_5H_5)_3(O_2CC_6H_5)_6$ molecular cation, with C$_3$ symmetry, is composed of three six-fold coordinated spin-carrying Fe$^{3+}$ cations that form a perfect equilateral triangle. Experimental reports demonstrating the spin-electric effect in this system also identify the presence of a magnetic uni-axis and suggest that this molecule may be a good candidate for an externally controllable molecular qubit. Here we demonstrate, using standard density-functional methods, that the spin-electric behavior of this molecule could be even more interesting as there are energetically competitive reference states associated with both high and low local spins (S=5/2 vs. S=1/2) on the Fe$^{3+}$ ions. Each of these structures allow for spin-electric ground states. We find that qualitative differences in the broadening of the Fe(2s) and O(1s) core levels and the single-spin anisotropy Hamiltonian may be used to confirm whether the high-spin manifold is lower in energy than the low-spin manifold.