Engineering exchange bias at the interface of self-polarized ultrathin ferroelectric Ba⁢Ti⁢O3 and ferromagnetic La0.67⁢Sr0.33⁢Mn⁢O3

DOI: 10.1103/PhysRevApplied.22.054035

Authors: Tuhin Maity (University of Cambridge; Indian Institute of Science Education and Research) , Manisha Bansal (Indian Institute of Science Education and Research) , Nives Strkalj (University of Cambridge; Institute of Physics (Croatia)) , Kapildeb Dolui (University of Cambridge) , Di Zhang (Purdue University) , Zihao He (Purdue University) , Guillaume F Nataf (University of Cambridge) , Adam Lovett (University of Cambridge) , Massimo Ghidini (University of Cambridge; Diamond Light Source; University of Parma) , Sarnjeet S. Dhesi (Diamond Light Source) , Ping Lu (Sandia National Laboratories) , Haiyan Wang (Purdue University) , Weiwei Li (University of Cambridge; Nanjing University of Aeronautics and Astronautics) , Judith L. Macmanus-Driscoll (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Applied , VOL 22

State: Published (Approved)
Published: November 2024
Diamond Proposal Number(s): 22427

Abstract: We investigate the emergence and optimization of conventional exchange bias (EB) in ultrathin (<10 nm) ferroelectric (FE) Ba⁢Ti⁢O3 (BTO)/ferromagnetic (FM) La0.67⁢Sr0.33⁢Mn⁢O3 (LSMO) epitaxial bilayers without an antiferromagnetic (AFM) material. The EB originates from the electronic orbital reconstruction at the FE-FM interface due to the ferroelectric polarization. We achieve maximum EB of approximately 42 Oe with single-domain polarization in nine-unit-cell-thick BTO, setting the BTO thickness above the critical threshold for ferroelectricity yet below the thickness of strain relaxation and multidomain breakdown. Furthermore, the LSMO layer needs to be thick enough to sustain both the FM layer and polarization-induced AFM spin configuration at the LSMO/BTO interface, yet as thin as possible to enable the EB loop shift. The temperature, training, field, and thickness dependence of the EB confirm that the LSMO/BTO interface exhibits conventional EB despite its unconventional origin. Using x-ray magnetic circular dichroism, scanning transmission electron microscopy, and density-functional-theory calculations, we confirm that the macroscopic EB effect originates from the interfacial AFM spin configuration in LSMO driven by FE-induced d-orbital modifications in interfacial Mn ions. Thus, we engineer strong interfacial EB coupling in artificial multiferroics without a conventional AFM material by controlling FE polarization, highlighting the potential for advanced spintronic applications.

Journal Keywords: Exchange bias; Spintronics; Surface & interfacial phenomena; Ferroelectrics; Ferromagnets; Magnetic thin films; Multiferroics; Transition metal oxides

Diamond Keywords: Ferroelectricity; Ferromagnetism; Spintronics; Data Storage

Subject Areas: Materials, Physics


Instruments: I06-Nanoscience (XPEEM)

Added On: 20/11/2024 11:53

Documents:
PhysRevApplied.22.054035.pdf

Discipline Tags:

Surfaces Quantum Materials Multiferroics Physics Hard condensed matter - structures Electronics Components & Micro-systems Information & Communication Technologies Magnetism Materials Science interfaces and thin films

Technical Tags:

Spectroscopy Circular Dichroism (CD) X-ray Magnetic Circular Dichroism (XMCD)