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物理教室談話会


題目
NEW TYPE OF FERROIC PHASE TRANSITIONS IN BORACITES:
FERROTOROIC PHASE TRANSITION
講師 Dr. Daniil G. Sannikov
      Institute of Crystallography, Russia
日時 2月1日(金)16:00-17:30
場所 コラボレーションセンター4階 共同研究室(403号室)
岡山大学津島キャンパス内
要旨  The third dipole moment (in addition to the polarization Pi and magnetisation Mi), which is called the toroidal moment Ti, was comparatively recently discovered in macroscopic electrodynamics.
   Borasites, M_3B_7O_13X, where M is a bivalent metal and X is a halogen, are the first reliable example of ferrotoroics, i.e. the crystals with ferrotoroic phase transitions (components of Ti are order paramers).
   These transitions at the same time are improper ferroelectric and ferroelastic transitions and also week ferromagnetic transitions. From the thermodynamic potential the spontaneous components of Ti, Mi, and Pi and also the susceptibilites: dielectric dPi/dEj, magnetic dMi/dHj, and magnetoelectric dPi/dHj=dMj/dEi, which show specific temperature anomalies, are derived.
 
 
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