The method of producing monocrystalline or multicrystalline blanks, especially silicon blanks, by using a vertical-gradient-freeze method, includes providing a crucible with a rectangular or square-shaped cross section and a heating jacket disposed around the crucible, which has a number of flat heating elements with a meandering course disposed on side faces of the crucible. The permanent magnet rotor includes at least one permanent magnet and a rotor core including a first end and a second end. Attachment of the wire to the bracket is faster and easier.