Carrier Density Dependence of Magnetoresistance inTl2Mn2−x

Colossal electroresistance and colossal magnetoresistance in spinel multiferroic CdCr2S4

“…In the ferromagnetic semiconductors, another mechanism due to the magnetic polarons could lead to CMR. [16][17][18] It is plausible that CMR of CdCr 2 S 4 (also a ferromagnetic semiconductor) is due to the latter mechanism. Indeed, the origin of CMR in the similar systems of Cd-doped FeCr 2 S 4 and HgCr 2 S 4 has been discussed in the context of magnetic polarons.…”

Magnetic ordering of Mn and Ru in (La0.52Ba0.48) (Mn0.51Ru0.49)O3

“…The doping of Mn sites in (La 1-x A x ) (Mn 1-y B y )O 3 systems with ruthenium means that charges are transported through the Mn-O-Mn network via double-exchange interactions [13]. Recently, studies on a similar interesting system, Tl 2 Mn 2-x Ru x O 7 compound [14,15], have shown the Ru 4+ substitution in the Mn 4+ networks, resulting in a magnetoresistance increase as the charge density in the Tl-O conduction band is reduced. Goodenough [16] pointed out that ferromagnetism is governed not only by the double exchange reactions, but also by the nature of the superexchange interactions.…”

A study of two-dimensional magnetic polaron

“…Recently, the study of colossal magnetoresistance has become a hot topic [1][2][3][4][5] , and the related discussion about magnetic polaron has also drawn much attention. Most of the studies on magnetic polaron are based on double-exchange model [6][7][8][9] , from which we obtain the result that self-trapped magnetic polaron (STMP) only exists in anti-ferromagnetic materials, while no polaron would be found in a ferromagnetic material with polarized carriers due to dispersion of the probability density distribution.…”