Probing the anharmonicity of the potential well for a magnetic vortex core in a nanodot.
The anharmonicity of the potential well confining a magnetic vortex core in a nanodot is measured dynamically with a magnetic resonance force microscope (MRFM). The stray field of the MRFM tip is used to displace the equilibrium core position away from the nanodot center. The anharmonicity is then inferred from the relative frequency shift induced on the eigenfrequency of the vortex core translational mode. An analytical framework is proposed to extract the anharmonic coefficient from this variational approach. Traces of these shifts are recorded while scanning the tip above an isolated nanodot, patterned out of a single crystal FeV film. We observe a +10% increase of the eigenfrequency when the equilibrium position of the vortex core is displaced to about one-third of its radius. This calibrates the tunability of the gyrotropic mode by external magnetic fields.
Departamento de Física de Materiales, Universidad del Pais Vasco, 20018 San Sebastian, Spain.
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Sukhostavets
Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France.
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Pigeau
Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France.
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Sangiao
Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France.
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de Loubens
Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France and Institute of Physics, Kazan Federal University, Kazan 420008, Russian Federation.
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Naletov
Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France.
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Klein
Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France.
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Mitsuzuka
Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France.
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Andrieu
Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France.
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Montaigne
Departamento de Física de Materiales, Universidad del Pais Vasco, 20018 San Sebastian, Spain and IKERBASQUE, The Basque Foundation for Science, 48011 Bilbao, Spain.
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Guslienko