High spin-low spin transitions in Cu 0.2Co 0.76Cr 1.83Se 4 semiconductor

Magnetization, ac and dc magnetic susceptibility measured in the zero- eld-cooled mode were used to study the high spin low spin transitions in polycrystalline Cu0:2Co0:76Cr1:83Se4 semiconductor. The real part component of fundamental susceptibility ′ 1(T) and its second ( 2) and third ( 3) harmonics revealed two spectacular peaks at 128 K and at 147 K, con rming the appearance of the spin-crossover phenomenon.Magnetization, ac and dc magnetic susceptibility measured in the zero- eld-cooled mode were used to study the high spin low spin transitions in polycrystalline Cu0:2Co0:76Cr1:83Se4 semiconductor. The real part component of fundamental susceptibility ′ 1(T) and its second ( 2) and third ( 3) harmonics revealed two spectacular peaks at 128 K and at 147 K, con rming the appearance of the spin-crossover phenomenon

Synthesis and Magnetic Properties of CuCr1:65Se4 Nanoparticles

CuCr1:65Se4 nanoparticles crystallize in the monoclinic Cr2Se3-type structure of the space group I2=m. The average crystallite size basing on the line broadening is less than 10 nm. With decrease of the size of grains a change from ferromagnetic to ferrimagnetic order, a lack of the magnetization saturation and a strong spin orbit coupling visible in the large value of the Landé factor g = 2:72 are observed. The change in magnetic order is caused by the change of the crystalline symmetry from the cubic phase to monoclinic one

Electrical and magnetic studies of ZnxMnyCr zSe4 p-type semiconductors

The structural, electrical and magnetic investigations carried out on the ZnxMnyCrzSe4 polycrystals with y = 0:19, 0.29 and 0.38 revealed the spinel structure with the Mn ions occupying tetrahedral sites, p-type conduction with polaronic transport at high temperatures and antiferromagnetic order with a Néel temperature of 20 K and a Curie–Weiss temperature of 103 K. With increasing Mn content in a sample both the effective magnetic moment and the re-entrant temperature increase while the first and second critical fields connected with a metamagnetic transition and the breakdown of the conical spin arrangement decrease, respectively. These results are interpreted in terms of giant cubic anisotropy as well as an effect of Mn impurities on the screw structure of ZnCr2Se4

The Mossbauer and x-ray studies of the spinel ferrites Cu0.5Fe0.8Cr2Se4 prepared by the ceramic method

Seleno-spinels with nominal chemical composition Cu0:5Fe0:5Cr2Se4 and Cu0:2Fe0:8Cr2Se4 were prepared as polycrystalline samples using ceramic method. The assumed composition was verified by wavelength-dispersive X-ray °uorescence spectrometry. The X-ray analysis was carried out in order to make phase analysis and to compare its results with those obtained with the Mossbauer spectroscopy

Spin crossover in CuxCoyCrzSe4 semiconductors

Magnetization and magnetic susceptibility measured in the zero-field-cooled mode were used to study the spin crossover transition in polycrystalline CuxCoyCrzSe4 compounds. With increasing Co content a transition from ferromagnetic order via ferrimagnetic one to antiferromagnetic-like behaviour was observed. This transition is accompanied with a lowering symmetry from cubic to monoclinic and for the latter the spin crossover phenomenon occurs. These results are considered in a framework of the ligand–field split and the spin–orbit coupling

The Mossbauer spectroscopy and analytical investigations of the polycrystaline compounds with general formula ZnxSnyCr2Se4

We present combined X-ray powder diffraction and Mossbauer 119Sn studies of polycrystalline compounds with a general formula ZnxSnyCrzSe4 (where x + y + z ¼ 3). The obtained single-phase compounds crystallize in the spinel cubic structure | Fd3m. Tin ions are found to occupy both tetrahedral and octahedral sublattices. On the contrary to the strong tetrahedral site preference energy of Sn, the presented data strongly suggest that the increase in lattice parameters with Sn doping is caused by Sn ions that incorporated into octahedral positions. A quadrupole and isomer shifts of 119Sn in (SnSe4)6¡ and (SnSe6)4¡ are also reported

Effect of cation substitution on critical fields in the n-type Zn xSnyCrzSe4 spinel semiconductors

The ac dynamic magnetic susceptibility was used to study a cation substitution on critical fields in polycrystalline (Zn0:87Sn0:048)Cr2:02Se4 and Zn0:93[Cr1:95Sn0:05]Se4 spinels with tetra- and octahedral coordination of Sn ions, respectively. An increasing static magnetic field shifts the Néel temperature TN to lower temperatures while a susceptibility peak at Tm in the paramagnetic region — to higher temperatures. Below TN the magnetic field dependence of susceptibility, Âac(H), shows two peaks at critical fields Hc1 and Hc2. The values of Hc1 decrease slightly with temperature while the values of Hc2 decrease strongly with temperature, especially for spinel with octahedral coordination of Sn ions, suggesting a weakness of the ferromagnetic component