Determining Magnetoelectric Coupling Phenomena in Multiferroic Materials by Spin Hall Magnetoresistance

Yu-Wei Chen^1*, Yen-Lin Huang¹

¹Department of materials sciecne and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Yu-Wei Chen, email:sanwho0814@gmail.com

Spin Hall Magnetoresistance (SMR) is a technique used to detect the spin states at material interfaces. When a current passes through a material with strong spin-orbit coupling (SOC) and transforms into a spin current, the resistance is obtained at several different values, depending on the interfacial spin states of the FM/AFM.
Bismuth Ferrite (BFO), a multiferroic material exhibiting both antiferromagnetic and ferroelectric properties at room temperature, is well-known for its magnetoelectric coupling characteristics. These characteristics have recently found applications in Magneto-Electric Spin-Orbit (MESO) devices.
In this research, pulsed laser deposition (PLD) was employed to grow La0.7Sr0.3MnO3 (LSMO) / BFO and SrRuO3 (SRO) / BFO thin films on STO (001) substrates. These two distinct bottom electrode layers induced different as-grown polarization states in the BFO layer, with LSMO causing an upward polarization and SRO inducing a downward polarization. Subsequently, we fabricated the Pt Hall bar patterns on the BFO [100] direction at angles ranging from 0 to 90 degrees. This approach allowed us to obtain SMR signals with angle dependence and simultaneously observe changes in the Néel vector under both "P up" and "P down" conditions. We also investigate the Néel vector configuration by X-ray linear dichroism (XMLD) to verify the SMR results.
In conclusion, we investigate the intricate antiferromagnetic structures of BFO thin films using two distinct methodologies, SMR and XMLD. Through our study, we successfully demonstrate the manipulation of the Néel vector through ferroelectric polarization.

Keywords: spintronics, spin hall magnetoresistance, BiFeO3, Néel vector, multiferroics