Remnant magnetization above room temperature in semiconducting Y_0.5Ca_0.5BaCo_4O_7

Abstract

The Y_0.5Ca_0.5BaCo_4O_7 compound exhibits four magnetic anomalies at the temperatures 387, 281, 52, and 14 K; all anomalies show characteristics typical for spin freezing into disordered states: frequency dependent transition temperature in the AC magnetic susceptibility together with relaxation of thermoremnant magnetization. Y_0.5Ca_0.5BaCo_4O_7 is a semiconductor with a small band-gap of 0.17 eV concluded from four-point conductivity measurements and the conductivity is proportional to T^(-3/4), suggesting an electron hopping mechanism involving Co^(2+) and Co^(3+) ions; at higher temperatures, double-exchange is the proposed reason for the strong magnetic interaction. At lower temperatures, super-exchange interactions start to compete with the double-exchange for domination and this competition together with geometrical frustrations in the structure are responsible for magnetic disorder down to 2 K. Covalence between Co and O is also discussed as additional reason for the strong magnetic interactions.

arXiv comment13 pages, 11 figures

References in corpus (5)

• Spin chirality on a two-dimensional frustrated lattice
• Structure, Magnetization and Resistivity of La${}_{1-x}$M${}_x$CoO${}_3$ (M = Ca, Sr, and Ba)
• Evidence for magnetic clusters in BaCoO${}_3$
• Spin-Glass State in $\mathrm{CuG}{\mathrm{a}}_2{\mathrm{O}}_4$
• Field-induced magnetic anisotropy in La0.7Sr0.3CoO3

Cited by in corpus (8)

• Magnetic Structure of CaBaCo4O7: Lifting of Geometrical Frustration towards Ferrimagnetism
• Approaching the ground state of the kagome antiferromagnet
• Spin dynamics, short range order and spin freezing in Y0.5Ca0.5BaCo4O7
• Spin correlations in the extended kagome system YBaCo3FeO7
• Spin-liquid phase and order-by-disorder of classical Heisenberg spins on the swedenborgite lattice
• The antiferromagnetic Ising model on the swedenborgite lattice
• A possible chiral spin-liquid phase in non-centrosymmetric $R$BaCo${}_4$O${}_7$
• Emergence of a 2d macro-spin liquid in a highly frustrated 3d quantum magnet