Results for “CaCoSi”

DOE OSTI2020

Materials Data on CaCoSi by Materials Project

CaCoSi is Matlockite structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one CaCoSi sheet oriented in the (0, 0, 1) direction. Ca2+ is bonded in a 4-coordinate geometry to four equivalent Si4- atoms. All Ca–Si bond lengths are 3.01 Å. Co2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CoSi4 tetrahedra. All Co–Si bond lengths are 2.31 Å. Si4- is bonded in a 8-coordinate geometry to four equivalent Ca2+ and four equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2024

A pyroxene-based quantum magnet with multiple magnetization plateaus

Pyroxenes (AMX 2 O 6 ) consisting of infinite one-dimensional edge-sharing MO 6 chains and bridging XO 4 tetrahedra are fertile ground for finding quantum materials. Thus, here, we have studied calcium cobalt germanate (CaCoGe 2 O 6 ) and calcium cobalt silicate (CaCoSi 2 O 6 ) crystals in depth. Heat capacity data show that the spins in both compounds are dominantly Ising-like, even after being manipulated by high magnetic fields. On cooling below the Néel temperatures, a sharp field–induced transition in magnetization is observed for CaCoGe 2 O 6 , while multiple magnetization plateaus beneath the full saturation moment are spotted for CaCoSi 2 O 6 . Our analysis shows that these contrasting behaviors potentially arise from the different electron configurations of germanium and silicon, in which the 3d orbitals are filled in the former but empty in the latter, enabling electron hopping. Thus, silicate tetrahedra can aid the interchain superexchange pathway between cobalt(II) ion centers, while germanate ones tend to block it during magnetization.

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