Correlation of Low-Frequency Noise to the Dynamics of Charge Transport Properties in AlO_x Magnetic Tunnel Junctions

Jhen-Yong Hong^1*, Isidoro Martinez², Cesar Gonzalez-Ruano², Farkhad G. Aliev², Minn-Tsong Lin^3,4,5, Pei-Fen Huang¹, Chi-Jia Lin⁶

¹Department of Physics, Tamkang University, New Taipei City, Taiwan
²Depto Fisica de la Materia Condensada, Universidad Autonoma de Madrid, Madrid, Spain
³Department of Physics, National Taiwan University, Taipei City, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei city, Taiwan
⁵Research Center for Applied Sciences, Academia Sinica, Taipei city, Taiwan
⁶Bachelor's Program in Advanced Material Sciences, Tamkang University, New Taipei City, Taiwan

* Presenter:Jhen-Yong Hong, email:jyhong@mail.tku.edu.tw

Low-frequency voltage noise is used to probe stochastic charge dynamics in AlO_x magnetic tunnel junctions (MTJs) exhibiting resistive switching (e.g. “memristance”) and tunneling magnetoresistance effects. 1/f noise and random telegraph noise (RTN) spectra are measured in the parallel and anti-parallel magnetization when the device is set to the high resistance state (HRS) and low resistance state (LRS). The suppressed noise magnitude and the frequency dependence strengthens at different resistance state are observed. Magneto-transport properties, I-V characteristics, and low-frequency noise spectroscopy of AlO_x MTJs are consistent with electron hopping fluctuations and rearrangements of configurations of the (re)distribution and the (re)migration of oxygen ions and oxygen vacancies in the AlO_x barrier. Such configurational fluctuations indicate that conductivity dynamics are important to charge transport in the interacting regime.

Keywords: Magnetic Tunnel Junction (MTJ), Magnetoresistance, Resistive Switching, Low Frequency Noise, Random Telegraph Noise (RTN)