High-Field Magnetoresistance of Organic Semiconductors

TL;DR

This study investigates high-field magnetoresistance in organic semiconductors, confirming theoretical models through experimental measurements of PEDOT:PSS diodes and magnetic resonance, highlighting the role of spin-mixing mechanisms.

Contribution

It provides experimental validation of the {g} spin-mixing model in high-field magnetoresistance of organic semiconductors, specifically in PEDOT:PSS diodes.

Findings

Magnetoresistance is influenced by field-dependent singlet-triplet mixing.

Experimental results support the g mechanism caused by g-factor differences.

Magnetic resonance measurements corroborate the spin-mixing model.

Abstract

The magneto-electronic field effects in organic semiconductors at high magnetic fields are described by field-dependent mixing between singlet and triplet states of weakly bound charge carrier pairs due to small differences in their Land\'e g-factors that arise from the weak spin-orbit coupling in the material. In this work, we corroborate theoretical models for the high-field magnetoresistance of organic semiconductors, in particular of diodes made of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) at low temperatures, by conducting magnetoresistance measurements along with multi-frequency continuous-wave electrically detected magnetic resonance experiments. The measurements were performed on identical devices under similar conditions in order to independently assess the magnetic field-dependent spin-mixing mechanism, the so-called {\Delta}g mechanism, which originates from differences in the charge-carrier g-factors induced by spin-orbit coupling.