Magnetoelectric control of frozen state in a toroidal glass

• Published in: Nature communications Vol. 4; no. 1; p. 2063
• Main Authors: Yamaguchi, Y., Kimura, T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-06-2013; Nature Publishing Group
• Subjects: 639/766/119; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723
• DOI: 10.1038/ncomms3063

The glass state of matter represents a frozen state of an atomically disordered system with local order only. Instead of atoms, systems with glassy states of magnetic and electric dipole moments in solids are known as spin and dipole glasses, respectively. In these conventional glasses, slow dynamics, such as relaxation and memory phenomena, are characteristics of their magnetic/dielectric properties. Here we propose a new glassy state in solids, a ‘toroidal glass’, in which toroidal moments—vector-like electromagnetic multipole moments breaking both space inversion and time reversal symmetries, and producing a linear magnetoelectric coupling—are randomly oriented and frozen. We investigate the dynamics of a linear magnetoelectric effect in Ni
0.4
Mn
0.6
TiO
3
and find that the magnetoelectric responses strongly depend on the magnetoelectric cooling history and show striking memory effects. These unusual magnetoelectric dynamical features can be explained in the framework of a toroidal glass in which the toroidal frozen state can be controlled magnetoelectrically.
Ferrotoroidic order has long been suggested as the fourth form of ferroic orders, in addition to known ferroelastic, ferroelectric and ferromagnetic order. Yamaguichi and Kimura propose the existence of a new glass state in solids with ferrotoroidic order and demonstrate the concept in Ni
0.4
Mn
0.6
TiO
3
.