Raman studies of nearly half-metallic ferromagnetic CoS₂

Abstract

We measured the Raman spectra of ferromagnetic nearly half metal CoS2 in a broad temperature range. All five Raman active modes Ag, Eg, Tg(1), Tg(2) and Tg(3) were observed. The magnetic ordering is indicated by a change of the temperature dependences of the frequency and the line width of Ag and Tg(2) modes at the Curie point. The temperature dependence of the frequencies and linewidths of the Ag, Eg, Tg(1), Tg(2) modes in the paramagnetic phase can be described in the framework of the Klemens approach. Hardening of the Tg(2), Tg(1) and Ag modes on cooling can be unambiguously seen in the ferromagnetic phase. The linewidths of Tg(2) and Ag modes behave a natural way at low exciting laser power (decrease with decreasing temperature) in the ferromagnetic phase. At high exciting laser power the corresponding linewidths increase at temperature decreasing below the Curie temperature. Then as can be seen the line width of Ag mode reaches a maxima at about 80K. This intriging feature probably signifies a specific channel of the optical phonon decay in the ferromagnetic phase of CoS2. Tentative explanations of some of the observed effects are given, taking into account the nearly half metallic nature of CoS2.

Synthesis of Lattice‐Contracted Cobalt Disulfide as an Outstanding Oxygen Reduction Reaction Catalyst via Self‐assembly Arrangement

“…The Raman spectroscopy was also performed for the crystal structure of samples. As shown in Figure 1b, five phonon modes were clearly assigned in Raman spectra of O−CoS 2 , [11] while the pristine CoS 2 with lower crystallinity presented relatively low peak intensity and sharpness. In the crystal structure of CoS 2 , a covalent bond existed between the two nearest sulfur atoms, which can be reflected by the E g mode, that is, a pure librational vibration for dumbbells.…”

A highly active and stable hydrogen evolution catalyst based on pyrite-structured cobalt phosphosulfide

“…3d , blue trace). These Raman peaks could be attributed to the characteristic E g and A g vibrational modes corresponding to the in-phase stretching and pure libration of the S–S dumbbells in the pyrite structure 29 30 31 . For the CoS|P/CNT, the peaks slightly shifted to higher wavenumber ( Fig.…”

Laser‐Induced Reactive Deposition of Nanostructured CoS2‐ and Co2CuS4‐Based Films with Fenton Catalytic Properties

“…The values of 190 cm –1 , 470 cm –1 and 670 cm –1 are in agreement with the CoS 2 phase and similar values of Raman peaks can be also attributed to Co 9 S 8 (≈ 470 cm –1 , 513 cm –1 , 610 cm –1 and 676 cm –1 ). The broad band centered around 320 cm –1 suggests the presence of an amorphous phase which could encompass the contribution of the Eg mode of cubic‐pyrite type structure of CoS 2 and/or amorphous CoO …”