We studied magnetism of Sr${}_{2}$ScO${}_{3}$CoAs, a member of the group of layered compound with CoAs conducting layers, by using successfully synthesized polycrystalline sample. As a result of magnetic and electric resistivity measurements, Sr${}_{2}$ScO${}_{3}$CoAs was revealed to be an itinerant electronic ferromagnet with the Curie temperature ${T}_{\mathrm{C}}$ $=$ 48 K. We discussed the magnetism of this compound within the spin fluctuation theory for three-dimensional itinerant electronic ferromagnets in the ordered state and also pointed out possible quasi-two-dimensional behavior observed in magnetism.

Itinerant electronic ferromagnetism in Sr 2 ScO 3 CoAs with largely spaced CoAs conduction layers

We synthesized a series of molybdenum and tungsten η-carbide-type compounds and measured their magnetic susceptibility χ. Although the enhancement of χ was observed in several compounds, apparent magnetic order was found only in Fe3W3N (ferromagnetic at 110 K). The broad peak in χ of Fe6W6C is possibly due to antiferromagnetic order. Itinerant electron metamagnetic transitions were observed in Fe3W3C, Fe6W6C, Fe6W6N and Co6W6C. The magnetic enhancement depends on the 3d element in the order Fe > Co > Ni corresponding to DOS at theFermi energy in η-12 systems, whereas no clear trend has been observed in η-6 systems.

https://iopscience.iop.org/article/10.1088/1742-6596/344/1/012017/pdf

Magnetic susceptibility of η-carbide-type molybdenum and tungsten carbides and nitrides

η-carbide-type transition-metal compounds include the frustrated stella quadran-gula lattice. Due to characteristics of the lattice, we expect subtle transitions between frustrated and non-frustrated states. Here, we report metamagnetic transitions newly found in η-carbide-type compounds Fe3W3C, Fe6W6C and Co6W6C.

http://iopscience.iop.org/article/10.1088/1742-6596/320/1/012069/pdf

Metamagnetism of η-carbide-type transition-metal carbides and nitrides

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/171246/1/j.jallcom.2012.10.161.pdf

Itinerant electron magnetism of η-carbides Co6M6C and Ni6M6C (M=Mo and W)

A polycrystalline sample of Fe2GeMo3N has been synthesized by the reductive nitridation of a mixture of binary oxides in a flow of 10% dihydrogen in dinitrogen The reaction product has been studied by magnetometry, neutron diffraction and Mossbauer spectroscopy over the temperature range 18 ≤ T/K ≤ 700 The electronic structure and magnetic coupling have been modelled by Density Functional Theory (DFT) and Monte Carlo methods Fe2GeMo3N adopts the cubic η-carbide structure with a = 111630(1) A at 300 K The electrical resistivity was found to be ∼09 mΩ cm over the temperature range 80 ≤ T/K ≤ 300 On cooling below 455 K the compound undergoes a transition from a paramagnetic to an antiferromagnetic state The magnetic unit cell contains an antiferromagnetic arrangement of eight ferromagnetic Fe4 tetrahedra; the ordered atomic magnetic moments, 190(4) μB per Fe atom at 18 K, align along a direction DFT predicts an ordered moment of 1831 μB per Fe A random phase approximation to the DFT parameterised Heisenberg model yields a Neel temperature of 549 K, whereas the value of 431 K is obtained in the classical limit for spin Monte Carlo calculations confirm that the experimentally determined magnetic structure is the lowest-energy antiferromagnetic structure, but with a lower Neel temperature of 412 K These results emphasise the potential of these computational methods in the search for new magnetic materials

Magnetic properties of Fe2GeMo3N; an experimental and computational study

We report the magnetic properties of the cobalt molybdenum η-carbide-type compounds Co 3 Mo 3 C and Co 3 Mo 3 N. The magnetic susceptibility χ of Co 3 Mo 3 C shows a Curie–Weiss temperature dependence at high temperatures and a broad maximum at around 100 K, whereas that of Co 3 Mo 3 N shows a nearly temperature-independent enhanced Pauli paramagnetic behavior. The absence of a magnetic long-range order was confirmed by the nuclear magnetic resonance technique in both the compounds. As expected from the broad maximum of χ, we observed an itinerant electron metamagnetic transition at around 37 T in Co 3 Mo 3 C.

Yasuki Umemoto

Papers

Itinerant Electron Metamagnetism in $\eta$-Carbide-Type Compound Co3Mo3C