Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 99: Organic Semiconductors: Transport

HL 99.2: Talk

Friday, March 30, 2012, 09:45–10:00, EW 203

Understanding charge and spin transport properties of π−conjugated polymers — •Sandip Bhattacharya, Mauro Ferreira, and Stefano Sanvito — School of Physics and CRANN, Trinity College Dublin, Ireland

An efficient spin polarized transport through Organic Spin Valves, which is quinessential for a high and stable MR, require a much broader understanding of how spins travel through an organic media. In this respect the general consensus among the Organic Spintronics community on the principal spin scattering mechanisms is often quite contentious. In the current work, we discuss our microscopic approach to this problem [1]. Organic π-conjugated polymers are represented by using a Hubbard-Peierls model that also includes Hyperfine (HF) and Spin Orbit interactions (SOC). The phononic degrees of freedom and the nuclear spins in the Hamiltonian are evolved in Monte Carlo simulations. The transport observables investigated are the spin-polarized conductance (Landauer-Buttiker formalism) and the charge carrier mobility (Kubo formula). We are able to extract the spin diffusion length and spin lifetimes of carriers from the observables and thereby compare them directly to experimental results. The problem at hand is quite an intriguing one involving a significant deal of complexity in terms of controlling the number of microscopic parameters. The strengths of the SOC constant and the HF integral are estimated from first-principle calculations. In this work we present our results on spin and charge transport properties calculated in the entire region of parameter space of the problem.

[1] S. Bhattacharya et al JPCM, 23, 316001 (2011).