Symmetry and macroscopic manifestations of a long-range spin order of non-orientational type in crystals
Abstract
Abstract In the framework of symmetry consideration a long-range spin order of a non-orientational (correlation) kind is studied in different types of crystal lattices. A purely correlation (non-orientational) long-range spin order is characterized by zero time-average spin moments in arbitrary points of a crystal. Nevertheless, the magnetic symmetry of the crystal proves to be lower as compared to the genuine paramagnetic phase, but, at the same time, higher than the symmetry of the orientationally ordered magnetic state. We shall consider a few specific systems in which the existence of such an intermediate phase appears almost inevitable by virtue of general symmetry consideration. Much attention is given to the possible macroscopic manifestations of a non-orientational spin order. Among them are different kinds of crystal lattice distortions, e.g., magnetostriction, ferroelectricity (as a side effect), etc. Key Words: magnetic symmetrylow-dimensional magnetic structuresmagnetostrictionmacroscopic symmetry