Electric current noise in mesoscopic organic semiconductors induced by nuclear spin fluctuations

We demonstrate that the nuclear spin fluctuations lead to the electric current noise in mesoscopic samples of organic semiconductors, which show the pronounced magnetoresistance in weak magnetic fields. For the bipolaron and electron-hole mechanisms of organic magnetoresistance, the current noise spectrum consists of the high-frequency peak related to the nuclear spin precession in the Knight field of the charge carriers and the low-frequency peak related to the nuclear spin relaxation. The shape of the spectrum depends on the external magnetic and radio frequency fields, which allows one to prove the role of the nuclei in the magnetoresistance experimentally.

Automated summary

In organic semiconductors, nuclear spin fluctuations lead to electric current noise, manifesting as pronounced magnetoresistance, with the current noise spectrum reflecting the role of nuclei in magnetoresistance through high-frequency peaks related to nuclear spin precession and low-frequency peaks related to nuclear spin relaxation, dependent on external magnetic and radio frequency fields.