Nanoscale physics 

Domain wall with Bloch point in ferromagnetic cylindrical nanowire 
Shevchenko A.B.1, Barabash M.Yu.2
1 G.V. Kurdymov Institute of Metal Physics of the NAS of Ukraine, 
Vernadskogo pr., 36, Kyiv-03142, Ukraine 
2 Technical Centre of the NAS of Ukraine, 
Pokrovskya str., 13, Kyiv-04070, Ukraine 
E-mail: mbarabash@nasu.kiev.ua 

The study of ferromagnetic nanowires (FNs) is an important task of nanoscale physics due to their unique properties. Among the wide variety of FNs, here we consider cylindrical nanowires, in which the formation of domain walls (DWs) takes place. It is clear that thermodynamic and magnetocaloric properties of cylindrical FNs [1-3] depend on DW magnetic structure. In this condition we will study DWs whose structure is characterized by Bloch point (BP). 
Using the indefinite Lagrange multiplier method the BP magnetic structure near its singularity center was determined [4]. It is shown that the behavior of the magnetization vector of Bloch point is affected by the symmetry of the system. It is found the critical radius of FN which ensnares the formation of a DW with BP. Given criteria is agree with the conclusion made in [5] regarding the critical radius of a permalloy cylindrical nanowire. Obtained results may be used in new methods for diagnosing both FNs and the magnetic structure of DWs in them. 

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