Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 60: Spin Structures and Magnetic Phase Transitions

MA 60.4: Talk

Thursday, March 17, 2011, 18:15–18:30, HSZ 103

Field-induced chirality in Dy/Y multilayer systems — •Dieter Lott¹, Sergey V. Grigoriev², Yury O. Chetverikov², Roger C. Ward³, Alexander Grünwald¹, and Andreas Schreyer¹ — ¹Helmholtz Zentrum Geesthacht, Geesthacht, Germany — ²Petersburg Nuclear Physics Institute, Gatchina, Russia — ³University of Oxford, Oxford, United Kingdom

In this work a series of Dy/Y multilayer samples with different Dy and Y layer thicknesses were studied to modify the interlayer and intra-layer RKKY coupling mechanism in the system. Polarized neutron reflectometry studies reveal the occurrence of chirality effects which can be manipulated by the application of a magnetic field applied during the Field Cooling process. The studies show intriguing features giving experimental hints for the theoretical interpretation of the observed phenomena. The obtained results can be interpreted taking into account the interplay of the RKKY and Zeeman interactions. Upon Zero Field cooling a helix inside one Dy layer suffers from the domain walls between the right- and left skewed structures. The magnetic field applied upon cooling, firstly, removes the domain walls inside the Dy layer. Secondly, the Zeeman interaction, coupling the non-compensated moments of the Dy layer with the magnetic field, competes with the interlayer RKKY interaction. When at a certain condition the two interactions compensate each other, the third anti-symmetric Dzyaloshinskii-Moriya interaction, appearing due to the lack of inversion symmetry on the interfaces, reveals itself through the sign of the average chirality of the structure.