Real-space observation of chiral magnetic order in metallic thin film at room temperature
Event details
| Date | 18.08.2011 |
| Hour | 14:00 |
| Speaker | Y.Z. Wu, Department of Physics, State Key Laboratory of Surface Physics, and Advanced Materials Laboratory, Fudan University, |
| Location |
PH H3 31
|
| Category | Conferences - Seminars |
Magnetic domain usually considered as the result of the competition of the exchange interaction the dipolar interaction and the magnetic anisotropy will not contain the chiral order.
However the Dzyaloshinskii-Moriya (DM) interaction which arises from the spin-orbit scattering of electrons
in a system with the broken inversion symmetry will cause the chiral magnetic order.
The Chiral spin structures were observed in the helimagnets like Fe0.5Co0.5Si
with a non-centrosymmetric crystal structure (Uchida et. al Science 311 359(2006) Yu et. al Nature 465 901(2010))
and in a Mn atomic layer on a tungsten substrate with the inversion symmetry broken at the interface (Bode et. al Nature 447 190(2007)).
Chirality in Nano scale magnets may play a crucial role in spintronic devices but it should be realized at room temperature for real applications.
In this talk we will present our results on the chiral magnetic order in Fe/Ni bilayer directly observed in real space at room temperature.
The experiments were performed with the spin polarized low-energy electron microscopy (SPLEEM) in Lawrence Berkeley national laboratory.
The SPLEEM can image the magnetic domain with the magnetization along the arbitrary orientations
which allows us to map the spin structure directly in real space. The Fe/Ni bilayer grown on Cu(001) exhibits the magnetic stripe domain phase.
The domain wall of the magnetic stripe is Néel-type which is different with all the previous theoretic predictions
and the in-plane components of the neighboring domain walls are always antiparallel.
Those results clearly demonstrate the existing of the cycloidal chiral magnetic order when the magnetic spins rotate.
The chiral order in the Fe/Ni bilayer is independent of the orientation and the width of the magnetic stripes but will disappear for the Ni layer thicker than 7ML.
The chirality can switch from the right-hand cycloid in Fe/Ni/Cu(001) to the left-hand cycloid in Ni/Fe/Cu(001)
which indicates the chirality is caused by the DM interaction mainly locating at the Fe/Ni interface.
The Monte-Carlo simulation can fully explain our results and also predicts a new type of the skyrmion spin structure.
Our results provide a new way to enhance the DMI at room temperature which will benefit the application of the spintronic devices.
Work in collaboration with G.Chen J.Zhu A.Quesada J.Li A.N’Diaye Y.Huo T.P.Ma Y.Chen H.Y.Kwon C.Won Z.Q.Qiu A.K.Schmid
Practical information
- General public
- Free
Contact
- Prof. Harald Brune