image: Angle-resolved Electrical Magneto-Chiral Effect demonstrated in SrRuO3-SrRu1-xTixO3-SrTiO3-SrTiO3 ABCC structure
Credit: ©Science China Press
Chirality is ubiquitous in nature such as chiral molecules, which originate from a pair of mirror-symmetric chiral enantiomers, referred to as the left-handed and right-handed forms, respectively. When inorganic materials possess a chiral structure, we can potentially apply them in novel electronic devices. For example, chiral carbon nanotubes can exhibit different magnitudes of electrical conductivity under opposing magnetic fields. This demonstrates the significant influence of chiral structures on the movement of electrons in a magnetic field, an effect known as the electrical magneto-chiral effect.
Magnetic oxides exhibit both electron correlation interactions and spin exchange interactions. In magnetic oxides with strong spin-orbit interactions, the addition of spin-orbit coupling further enriches the material's physical properties. Spin-orbit coupling with chiral interaction characteristics includes Rashba interaction and Dzyaloshinskii-Moriya interaction. The Rashba interaction-induced electromagnetic chiral effect has been discovered in oxide interface two-dimensional electron gas systems. However, research on the magnetochiral effect of Dzyaloshinskii-Moriya interaction is more complex and challenging.
A collaborative team led by members from ShanghaiTech University has achieved an angle-resolved magneto-chiral effect in artificially constructed oxide superlattices with broken inversion symmetry. The research team utilized laser molecular beam epitaxy to fabricate SrRuO3-SrRu1-xTixO3-SrTiO3-SrTiO3 superlattices with an A-B-C-C type atomic layer stacking. By rotating the sample in a magnetic field, they discovered that the sample direction with minimum resistance follows a left-handed and right-handed rotation modes, reflecting the chiral rotation of the magnetic easy axis. Dependent on the magnitude of the magnetic field, the maximum rotation angle is as large as 45°. The researchers attribute this behavior to the Dzyaloshinskii-Moriya interaction, which was intentionally engineered into the material.
This novel electromagnetic chiral effect is no longer limited to electrical responses where the current is parallel or antiparallel to the magnetic field, thus being entirely distinct from previous electromagnetic chiral effects. By achieving such a ‘semi-self-controlled’ spinning, the material can detect not only the direction of the magnetic field but also its strength.
The research shows strong potential to develop advanced angle-resolved spintronic devices, opening new possibilities for next-generation technologies.
Journal
Science Bulletin