A new strategy to create 2D magnetic order

April 10, 2020

Grain boundaries, which are consist of periodic arrangement of structural units and generally recognized as a two-dimensional "phase", can exhibit novel properties that are not existed in the intrinsic bulk crystal. The altered continuity of atomic bonding at grain boundaries cause local chemical environment dramatically change at a few unit cells, subsequently alter local electrical activity, magnetic order or other physical properties. The effects of grain boundary on properties is even more significant in the complex oxides due to the substantial interactions between lattice and other order parameters. Therefore, such an inhomogeneity of materials with grain boundary may dominate the entire response in nanoscale devices and have garnered particular interest in designing novel functional devices.

The nature of structural defects is determined by the atomic arrangements. Correlating the properties of single defect-based device with its specific atomic structure is vital and prerequisite for the device application. However, experimentally revealing such a structure-property relation is very challenging due to the atomic-size and chemical and structural complexity of defects, especially for the perovskite oxides that contain multiple elements.

In a new research article published in the Beijing-based National Science Review, scientists at Peking university, Institute of Physics, Chinese Academy of Sciences, and Tianjin University present atomic mechanism of spin-valve magnetoresistance at the asymmetry SrRuO3 grain boundary. The asymmetry atomic structure is very different from the common assumption based on prototype perovskite SrTiO3. The transport measurements exhibit the spin-valve magnetoresistance for the as fabricated centimeter-size and sub-nm-width Σ5(310) SrRuO3 grain boundary. Advanced scanning transmission electron microscopy and spectroscopy reveal its atomic arrangements based on which the first principles calculations reveal its electronic properties. Scientists find that owing to the Ru-O octahedron distortion near the asymmetric grain boundary, Ru d orbital reconstructs and results in reduction of magnetic moments and change of spin polarization along the grain boundary, forming a magnetic/nonmagnetic/magnetic junction. The calculations bridge the atomic structure with transport properties.

"Our findings can help us to understand the past transport properties such as the negative magnetoresistance and absence of tunneling magnetoresistance at the SrRuO3 grain boundary, and also predict new effects of SrRuO3 grain boundary such as the interfacial magnetoelectric coupling when SrRuO3 is used as a bottom electrode for growth of ferroelectric thin films." Prof. Peng Gao said, "In a broader perspective, control of defect structure at atomic scale can realize peculiar physical properties, providing us a new strategy to design devices with new low-dimensional magnetic properties by using boundary engineering."

This work was supported by the National Key R&D Program of China (2016YFA0300804), National Equipment Program of China (ZDYZ2015-1), National Natural Science Foundation of China (51672007 and 11974023), the Key-Area Research and Development Program of GuangDong Province (No. 2018B030327001?2018B010109009) and "2011 Program" Peking-Tsinghua-IOP Collaborative Innovation Center of Quantum Matter. Project was also supported by State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China
See the article:

Xujing Li, Li Yin, Zhengxun Lai, Mei Wu, Yu Sheng, Lei Zhang, Yuanwei Sun, Shulin Chen, Xiaomei Li, Jingmin Zhang, Yuehui Li, Kaihui Liu, Kaiyou Wang, Dapeng Yu, Xuedong Bai, Wenbo Mi, Peng Gao
Atomic origin of spin-valve magnetoresistance at the SrRuO3 grain boundary
Natl Sci Rev

The National Science Review is the first comprehensive scholarly journal released in English in China that is aimed at linking the country's rapidly advancing community of scientists with the global frontiers of science and technology. The journal also aims to shine a worldwide spotlight on scientific research advances across China.

Science China Press

Related Spin Polarization Articles from Brightsurf:

Anti-hacking based on the circular polarization direction of light
The Internet of Things (IoT) allowing smart phones, home appliances, drones and self-driving vehicles to exchange digital information in real time requires a powerful security solution, as it can have a direct impact on user safety and assets.

Graphene detector reveals THz light's polarization
Physicists have created a broadband detector of terahertz radiation based on graphene.

The return of the spin echo
The spin of particles can be manipulated by a magnetic field.

Squaring the circle -- Breaking the symmetry of a sphere to control the polarization of light
Scientists at Tokyo Institute of Technology (Tokyo Tech, Japan) and Institute of Photonic Sciences (ICFO, Spain) develop a method to generate circularly polarized light from the ultimate symmetrical structure: the sphere.

Spin, spin, spin: researchers enhance electron spin longevity
The electron is an elementary particle, a building block on which other systems evolve.

Ferried across: Figuring out unconventional spin transport in quantum spin liquids
Scientists at Tokyo Institute of Technology and Yokohama National University uncover the peculiar mechanism by which spin perturbations travel through a seemingly unpassable region of a quantum spin liquid system.

Optical shaping of polarization anisotropy in a laterally-coupled-quantum-dot dimer
Coupled-quantum-dot (CQD) structures are considered to be an important building block in the development of scalable quantum devices.

Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination
A hemispherical vanadium oxide cluster has a cavity that can accommodate a bromine molecule.

The spin state story: Observation of the quantum spin liquid state in novel material
The quantum spin liquid (QSL) state is an exotic state of matter where the spin of electrons, which generally exhibits order at low temperatures, remains disordered.

On-chip spin-Hall nanograting for simultaneously detecting phase and polarization singularities
A plasmonic spin-Hall nanograting structure that simultaneously detects both the polarization and phase singularities of the incident beam is reported.

Read More: Spin Polarization News and Spin Polarization Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.