Structure and magnetism in LaCoO₃

Abstract

The temperature dependence of the hexagonal lattice parameter c of single crystal LaCoO3(LCO) with H = 0 and 800 Oe, as well as LCO bulk powders with H = 0, was measured using high-resolution x-ray scattering near the transition temperature To ≈35 K. The change of c(T) is well characterized by a power law in T − To for T>To and by a temperature independent constant for T<To when convoluted with a Gaussian function of width 8.5 K. This behavior is discussed in the context of the unusual magnetic behavior observed in LCO as well as recent generalized gradient approximation calculations.

Geometric influence on the net magnetic moment in LaCoO$_3$ thin films

“…The strength of the magnetic interactions has been correlated with the angle of tilt between adjacent oxygen octahedra surrounding Co ions, given by the Co-O-Co bond angle. As the temperature decreases towards T = 40 K, the magnetic interaction weakens as the Co-O-Co angle decreases towards a critical angle of 163 • [2][3][4][5]. The critical angle of 163 • found experimentally is consistent with results from generalized gradient approximation calculations [6].…”

Origin of the net magnetic moment in LaCoO3

“…In particular, interesting behavior takes place as the temperature decreases to T ≈ 40 K where the bulk magnetic moment decreases precipitously. [70,53]. Modifications to this model can even explain surface and strain effects.…”

“…Experiments [53,29,59,70] and calculations [14] indicate that antiferromagnetic correlations are supported only for γ greater than the critical value γ C ≈ 163…”

“…• would result in essentially non-magnetic bonds [14,53,70]. First principles generalized gradient approximation (GGA) and local density approximation (LDA) [14] suggest the same dependence of the magnetization on Hamiltonian with a magnetic field of strength H z in the z direction,…”

A brief review on the effect of preparation conditions on magnetic properties of some A2MMnO6 (A = La, Eu and Y; M = Mg, Co, Ni) type perovskites

“…5,8,9 Similarly, it is also known that LaCoO 3 exhibits complex magnetic properties due to the structural transition associated with low spin and high spin Co 3? ions. 29 However , the combination of LaCoO 3 and LaMnO 3 shows a ferromagnetic ordering due to the Co 2? -O-Mn 4? and Co 3?…”