Magnetotransport and magnetic properties of sulfospinels Zn x Fe1−x Cr2S4

Abstract

Cr-based chalcogenide spinels, which do not have heterovalency and distortioninduced ions such as manganese oxides with perovskite structure, have demonstrated the existence of colossal magnetoresistance. In order to investigate the magnetotransport phenomena and magnetic properties of sulfospinels Zn x Fe 1−x Cr 2 S 4 , polycrystalline Zn x Fe 1−x Cr 2 S 4 samples were synthesized in the 0≤x≤0.2 range by a solid reaction method. The crystal structure for x=0.05, 0.1, and 0.2 turned out to be cubic at room temperature by X-ray diffraction measurement. In magnetoresistance measurement, Zn x Fe 1−x Cr 2 S 4 samples indicate that this system is semiconducting below about 150 K. The temperature of maximum magnetoresistance is almost consistent with Curie temperature. The isomer shift and the electric quadrupole shift of Zn x Fe 1−x Cr 2 S 4 samples by Mössbauer experiment show that Fe 2+ ions occupy the tetrahedral site in the spinel structure. As the Zn ions are substituted for Fe ions, the Jahn-Teller relaxation slows down and the electric quadrupole shift increases. The magnetotransport phenomena of Zn x Fe 1−x Cr 2 S 4 is related to Jahn-Teller effect and half-metallic electronic structure, which are different from the double exchange interactions of the manganite La-Ca-Mn-O system or the triple exchange interactions of sulfospinel Cu x Fe 1−x Cr 2 S 4 .

Experimental and theoretical charge density distribution of the colossal magnetoresistive transition metal sulfide FeCr2S4

“…In recent years, some TMSs containing mainly Fe and Cr, and sometimes Cu, 5 Co, 6 or Zn, 7 have been extensively studied since the discovery, in 1997, of an intrinsic colossal magnetoresistance ͑CMR͒ effect in the formally stoichiometric thiospinel FeCr 2 S 4 . 8 Magnetoresistance ͑MR͒ is defined as the relative change in the compound electrical resis-tivity upon application of an external magnetic field.…”

Mössbauer studies of Fe‐Zn sulphur spinels

“…Moreover, T N for the x = 0.3 is lower than that for the x = 0.1. It is interpreted that the superexchange interactions for the Fe-S-Cr link decrease by substituting Fe with nonmagnetic material Zn [10]. Mössbauer spectra of Fe 1-x Zn x Cr 2 S 4 were measured at various absorber temperatures ranges from 4.2 K to room temperature.…”

“…Moreover, T N for the x = 0.3 is lower than that for the x = 0.1. It is interpreted that the superexchange interactions for the Fe-S-Cr link decrease by substituting Fe with nonmagnetic material Zn [10].…”

Spinels in Meteorites: Observation Using Mössbauer Spectroscopy

“…However, other results obtained earlier in [36,37] demonstrate similar δ values: ~0.59 mm/s. Magnetization measurements of the troilite inclusion extracted from the Sikhote-Alin iron meteorite demonstrated two features in the ZFC/FC curves (Figure 11a): (i) a distinguished peak at 74 K; and (ii) a sharp magnetic transition at 168 K. It is well known that daubréelite has the ferrimagnetic-paramagnetic phase transition around 177 K (see, for instance, [30] and references therein) while recently a transition temperature of 166.5 K was found in [31]. Therefore, the magnetic phase transition at 168 K can be assigned to the ferrimagnetic-paramagnetic phase transition in daubréelite in the troilite inclusion.…”