TMR meeting Paris, 21-23.02.02 Polarisation and Magnetisation. Carmine Trimarco University of Pisa, Italy Dipartimento di Matematica Applicata ‘U.Dini’ Via Bonanno 25/B I-56126 Pisa e-mail: trimarco@dma.unipi.it Abstract. Polarisation and magnetisation are material quantities that are currently associated with the electromagnetic fields. However, there are materials that, otherwise purely thermoelastic, may undergo through a phase transition process, at the end of which they possibly exhibit also electromagnetic properties, such as ferro-electricity or ferro-magnetic properties. Typically, the crystalline unit cell suffers a permanent geometrical deformation in the phase transformation process. Such an intrinsic deformation possibly alters the initial distribution of the electric charges or of the atomic spins. As a result, electric or magnetic dipoles may arise in the crystalline cell. These dipoles, in turn, can arrange themselves in domains and possibly develop ferro-electricity or ferro-magnetism, in the absence of external electric or magnetic fields and under suitable thermal or mechanical loading, or both. This is the case of the barium titanate, which becomes anisotropic and ferro-electric below 120°C. Despite the fact that polarisation and magnetisation are governed by similar phenomenological equations in most of the cases of interest, these two quantities differ deeply from one another. Some of these differences are pointed out hereby, in rigid and in deformable bodies.
Polarisation and Magnetisation in Continua. Some remarks on similarities and differences.
TRIMARCO, CARMINE
2002-01-01
Abstract
TMR meeting Paris, 21-23.02.02 Polarisation and Magnetisation. Carmine Trimarco University of Pisa, Italy Dipartimento di Matematica Applicata ‘U.Dini’ Via Bonanno 25/B I-56126 Pisa e-mail: trimarco@dma.unipi.it Abstract. Polarisation and magnetisation are material quantities that are currently associated with the electromagnetic fields. However, there are materials that, otherwise purely thermoelastic, may undergo through a phase transition process, at the end of which they possibly exhibit also electromagnetic properties, such as ferro-electricity or ferro-magnetic properties. Typically, the crystalline unit cell suffers a permanent geometrical deformation in the phase transformation process. Such an intrinsic deformation possibly alters the initial distribution of the electric charges or of the atomic spins. As a result, electric or magnetic dipoles may arise in the crystalline cell. These dipoles, in turn, can arrange themselves in domains and possibly develop ferro-electricity or ferro-magnetism, in the absence of external electric or magnetic fields and under suitable thermal or mechanical loading, or both. This is the case of the barium titanate, which becomes anisotropic and ferro-electric below 120°C. Despite the fact that polarisation and magnetisation are governed by similar phenomenological equations in most of the cases of interest, these two quantities differ deeply from one another. Some of these differences are pointed out hereby, in rigid and in deformable bodies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
