CIQTEK SNVM Reveals Magnon Transport in BiFeO₃ (Advanced Functional Materials)
With the support of CIQTEK Scanning NV Microscopy (SNVM), researchers at Tsinghua University have directly visualized nanoscale spin cycloid structures in multiferroic BiFeO₃. This work, published in Advanced Functional Materials, provides the missing microscopic evidence linking crystal symmetry, magnetic structure, and anisotropic magnon transport, highlighting SNVM as a decisive tool for magnonics and low-power spintronic research. The study used the CIQTEK Scanning NV Probe Microscope (SNVM) Research Background: Magnon Transport in Multiferroic Oxides Magnon-mediated spin currents can propagate in magnetically ordered insulators with nearly zero energy dissipation, making them highly attractive for next-generation low-power spintronic devices. In multiferroic materials such as BiFeO₃, the coupling between ferroelectric and antiferromagnetic orders enables electric field control of magnons, a long-standing goal in spintronics. Despite this promise, the microscopic origin of weakly anisotropic magnon transport in rhombohedral phase BiFeO₃, commonly referred to as R-BFO, has remained unresolved. Addressing this challenge requires direct real-space characterization of nanoscale magnetic structures, which has long been inaccessible using conventional techniques. Technical Bottleneck: Lack of Direct Magnetic Structure Evidence Theoretical studies have predicted that R-BFO hosts a cycloidal spin structure that plays a critical role in suppressing strong anisotropy in magnon transport. However, experimental confirmation has been elusive. Traditional characterization techniques, such as X-ray magnetic linear dichroism, provide spatially averaged magnetic information and are unable to resolve nanoscale spin textures. As a result, the logical connection between crystal symmetry, magnetic structure, and magnon transport remained incomplete due to the absence of direct microscopic magnetic imaging. CIQTEK SNVM Approach: Direct Nanoscale Magnetic Imaging CIQTEK Scanning NV Microscopy (SNVM) overcomes these limitations by combining nanometer-scale spatial resolution with electron spin level magnetic field sensitivity. This enables non-invasive, quantitative imaging of local magnetic fields generated by complex spin textures inside functional materials. In this work, the research teams led by Prof. Yi Di from the State Key Laboratory of New Ceramic Materials and Prof. Nan Tianxiang from the School of Integrated Circuits at Tsinghua University employed CIQTEK SNVM magnetic imaging to directly probe the intrinsic magnetic structure of R-BFO. Key Findings Enabled by SNVM Magnetic Imaging Using CIQTEK SNVM, the researchers clearly observed a uniform cycloidal spin structure within R-BFO, with a characteristic periodicity of approximately 70 nanometers. The high spatial resolution of SNVM allowed precise quantification of the cycloid wavelength and confirmed that the magnetic structure exists in a single-domain state. By correlating SN...
