Tunneling through magnetic molecules with arbitrary angle between easy axis and magnetic field

Abstract

Inelastic tunneling through magnetically anisotropic molecules is studied theoretically in the presence of a strong magnetic field. Since the molecular orientation is not well controlled in tunneling experiments, we consider arbitrary angles between easy axis and field. This destroys all conservation laws except that of charge, leading to a rich fine structure in the differential conductance. Besides single molecules we also study monolayers of molecules with either aligned or random easy axes. We show that detailed information on the molecular transitions and orientations can be obtained from the differential conductance for varying magnetic field. For random easy axes, averaging over orientations leads to van Hove singularities in the differential conductance. Rate equations in the sequential-tunneling approximation are employed. An efficient approximation for their solution for complex molecules is presented. The results are applied to Mn12-based magnetic molecules.

Random transition-rate matrices for the master equation

“…An example is provided by the differential conductance calculated in Ref. [11] for a magnetic molecule with magnetic anisotropy axis not aligned with the applied magnetic field, where N = 20, but due to noncommuting terms in the Hamiltonian many rates are nonzero and are distributed over a broad range.…”

Electronic Transport as a Driver for Self-Interaction-Corrected Methods

“…General derivations of these equations have recently appeared in the literature (Elste and Timm, 2005;Koller et al, 2010;Leijnse and Wegewijs, 2008) together with several approximate solutions applied to SETs with quantum dots (Weinmann et al, 1995) and molecules (Koller et al, 2010;Leijnse and Wegewijs, 2008;Leijnse et al, 2009) including SMMs (Elste and Timm, 2005Timm, 2007;Timm and Elste, 2006). The simplest strategy is to solve these equations perturbatively in the tunneling Hamiltonian (Bruus and Flensberg, 2004).…”

Inelastic tunneling of electrons through a quantum dot with an embedded single molecular magnet

“…Recently, a great deal of effort has been paid to study quantum transport through SMMs both theoretically and experimentally [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The experiment of electron transport through the Mn 12 attached with nonmagnetic electrodes has shown that the macroscopic quantum tunneling of the SMM plays an important role due to breaking symmetry [3].…”