Giant Keplerate molecule Fe 30 - the first octopole magnet
نویسنده
چکیده
– The multipole expansion technique is applied to one of the largest magnetic molecules, Fe30. The molecule’s dipole, toroid and quadrupole magnetic moments are equal to zero (in the absence of magnetic field) so the multipole expansion starts from the octopole moment. Probably the Fe30 molecule is the most symmetrical magnetic body synthesized so far. The magnetization process is considered theoretically in different geometries. Some components of the octopole moment experience a jump while the magnetization rises linearly up to its saturation value. An elementary octopole moment consisting of four magnetic dipoles is proposed as a hint for designing of an experiment for measurement of octopole magnetic moment components. Introduction. – Multipole expansion of the electrical field generated by a number of electrical charges has been widely used in theoretical physics. However, multipole expansion of magnetic fields generated by a system of permanent currents is less known. The starting point of such an expansion is a well known formula for the vector potential of the magnetic field:
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