Spin-state transition of Co ion (S = 2 → S = 5/2) in hole substituted 1D chain of Ca₃Co₂O₆

Abstract

We have discovered spin-state transition (S = 2 to S = 5/2) of Co ions due to Mg substitution in the Ca3Co2O6 apparent in the magnetic susceptibility, XPS, and first-principles study. We also examine the effect of Mg substitution on the magnetic and electronic structure of Ca3Co2O6 by first- principles calculations. It involves generalized gradient approximation with Coulomb interaction (U) in exchange-correlation energy functional. Our study shows a reasonable agreement between effective magnetic moment (μef f ) determined from the Curie–Weiss fit with that from the XPS analysis and first-principles calculations study. We have attributed the decrease in positive intra-chain exchange interaction constant (J1/kB ) to the antiferromagnetically coupled induced Co4+ ions (S = 5/2) arising from the Mg2+ ions substitution. The in-field meta-magnetic transitions in the isothermal M(H) curves below the critical field (Hc ) have been accurately mapped and successfully explained by the change in magnetic entropy (ΔS) calculations and Arrott plots. Electronic structure study reveals hole-type doping of Mg atom, and the Fermi level (EF ) shifts below. Density of state and band structure calculation indicates strong hybridization between partial states of Co-3d and O-2p orbitals for the Mg-doped compound due to which the band crossing at Fermi level is observed, and a hole- type Fermi surface is formed.

Correlation between magnetic and dielectric anomalies arising due to spin-chain arrangements in the paramagnetic phase of 1D Ca3Co1.9Bi0.1O6

“…3(a)) for Ca 3 Co 1.9 Bi 0.1 O 6 compound. For the sake of completeness, we want to mention that this compound undergoes two transitions the partially disordered antiferromagnetic phase (T c1 = 23 K) and the short-range glassy state (T c2 = 10.3 K) [9,15,16]. However, the scope of this work lies much above these temperatures.…”

Multilevel thermal memory cell based on cyclic temperature experiment under glassy phase of frustrated magnet

“…However, in an earlier report for Ca 3 Co 2−x Mn x O 6 , the increased relaxation time for intermediate Mn-compositions has been attributed to the effect of chemical disorder [24]. Therefore, with impurity substitution in Ca 3 Co 2 O 6 , the interplay of competing magnetic interactions and chemical disorder effects become crucial for glassy features [24][25][26][27][28][29][30]. The challenging issue in this compound is the single-phase synthesis of doped samples to explore the new mechanism of in-site originated disorder, which provides a plethora of anisotropy types.…”

Enhanced Magnetic Properties of Electrodeposited Co2FeSn Film with High Structural Order

“…Electronic structure of CFS Heusler alloy was evaluated using density functional first-principle calculations based on pseudopotential with projector augmented wave (PAW) in Vienna ab initio simulation package (VASP). 2,4,25,26 The exchange-correlation energy in electronic interaction was computed using the Perdew-Burke-Ernzerhof (PBE) functional. 27 A CFS supercell consisting of 16 total atoms (8 Co, 4 Fe and 4 Sn) was used in the calculations.…”