Abstract
The field at the center of a Lorentz-sphere due to all dipoles within this sphere has been calculated, assuming inhomogeneous orientations of the dipoles in the sphere, as one must expect in real crystals. This field has very often been neglected. The calculation shows the existence of a coupling field which stiffens the dipole directions against localized torques due to “distortion fields”. In the case of ferromagnetism, one can calculate the coupling field of an expanded Lorentz volume. This is analogous to the quantummechanical exchange field, which is due to the excess exchange energy. In many cases the above dipole coupling field is more important than the wellknown exchange field because the “dipole coupling constants” exceed the exchange constant by orders of magnitude.
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In Prof. Dr. W.Rollwagen zum 60. Geburtstag gewidmet.
Diese Arbeit entstand zum Teil während eines Gastaufenthaltes am California Institute of Technology, Pasadena, California. Dafür bin ich dieser Hochschule, den Institutionen, welche den Aufenthalt finanziell unterstützten und besonders den Professoren C. H.Wilts und F. B.Humphrey zu großem Dank verpflichtet.
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Hoffmann, H. Das Lorentzfeld und die Dipolkopplung. Z. Physik 224, 156–171 (1969). https://doi.org/10.1007/BF01392244
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DOI: https://doi.org/10.1007/BF01392244