Study of the Morin transition in nearly perfect crystals of hematite by diffraction and topography

✍ Scribed by V.V. Kvardakov; J. Sandonís; K.M. Podurets; S.Sh. Shilstein; J. Baruchel

• Book ID: 103935995
• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 810 KB
• Volume: 168
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(91)90057-l

✦ Synopsis

The spin reorientational magnetic Morin transition is investigated on nearly pertect crystal\ of hematite hq combining neutron diffraction, neutron and synchrotron radiation topography. and magnetization mea\urcmcnts. The wmple\ at-c platclct shaped crystals, with their main surface parallel to the (I I I) hasal plane. The magnetization measurementa show that the main part of the transition occurs over a rather narrow temperature range (about 3 K). whereas this range appear\ hroadcned to about 13 K on the neutron diffraction curves. Neutron topographs show the whole crystal image during transition and X-ray topographs show zone contrast when modifying the applied magnetic field. These experimental fact\ indicate that the intcrfaccs which separate the weakly ferromagnetic and the antiterromagnetic phases are parallel to the main surfaces of the crystals. This is the hasis for a very simple model which explain. through severe extinction cffccts. the apparent contradiction hctwccn neutron diffraction and magnetization measurements. and tend\ to an estimation of the crystal perfection parameters OYZI-4526/01/$0.1.50