ANISOTROPY OF BONDS AT ANTIFERROMAGNETIC TRANSITION IN MnTe-BASED LAYERS

K. Lawniczak-Jablonska1*, I.N. Demchenko1 , W. Szuszkiewicz1 , E. Piskorska1 , E. Dynowska1 , E. Janik1 , and A. Traverse2

1 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02 668 Warsaw, Poland

2 LURE, Universite de Paris-Sud, Bat. 209D, 91405 Orsay, Cedex, France

MnTe is a well known magnetic semiconductor, which in the bulk form crystallizes in the hexagonal (NiAs) structure. Due to an application of nonequilibrium growth technique, like molecular beam epitaxy (MBE), thin layers and quantum structures containing zinc-blende MnTe (the metastable phase of this compound) can also be obtained. All zinc-blende manganese chalcogenides are rare examples of fcc Heisenberg systems with strongly dominating antiferromagnetic (AF) exchange interaction between the magnetic nearest-neighbours (corresponding to the second neighbours in the crystal lattice) and significantly weaker exchange interaction between the magnetic nextnear-neighbours (this interaction is also of the antiferromagnetic type and corresponds to the fourth neighbours in the lattice). This kind of the exchange interactions between Mn ions results in magnetic AFIII type structure below the magnetic phase transition temperature.

https://www.researchgate.net/publication/268292097_ANISOTROPY_OF_BONDS_AT_ANTIFERROMAGNETIC_TRANSITION_IN_MnTe-BASED_LAYERS

In the case of zinc-blende MnTe the Mn spins are not able to satisfy simultaneously all the AF interactions with their nearest magnetic neighbors. As a consequence the magnetic frustration phenomenon occurs at low temperatures (Fig. 1). Perfect AF order exists in planes perpendicular to Z direction, the phenomenon of frustration is well seen for atoms lying in planes parallel to this direction (for example, on the left side Mn atom 4 there are two Mn spin oriented “down”, and on the right side two other spins oriented “up”). The magnetic structure shown in Fig. 1 is stable only after taking into account also the magnetic interactions between the nextnear neighbors.