Crystal-field, exchange interactions and magnetism in pyrochlore ferromagnet R2V2O7 (R3+=Y, Lu)

Origin of ferromagnetic ordering of Lu[sub 2]V[sub 2]O[sub 7] studied with crystal-field theory in the mean-field approach

“…and Zeeman interactions as perturbations. Following detailed calculations [4], we obtain the gvalues as: ' 0 = 3224 cm 1 and total 2 D splitting becomes ' 1 =16216 cm 1 = 2.01 eV which agrees well with the previous results [1]. Calculated single-ion CF susceptibility F CF matches appreciably with the observed data at T >180 K, but differs below180 K (Fig.…”

“…The ground state wave function of LuV is < g = 0.9997 |0, r1/2² 0.01976 |r1, B1/2² r 0.012 |B2, B1/2² [4]. The other CF levels are well-separated above the ground state.…”

“…When introducing FM exchange constants O || =22.8 and O A =21.7 T/P B , the renormalized F matches well the experimental results down to ~100 K. Below 100 K, F increases very sharply due to long-range magnetic ordering or correlation among n.n. V 4 tetrahedra which may induce the splitting of the lowest Kramers doublet [4,6]. To explain the sharp rise of F below T c , we introduce a single-ion FM-like Heisenberg exchange Hamiltonian [6] in terms of thermally averaged total angular momentum…”

Magnetic properties of a new vanadate Cu13Fe4V10O44

“…They are probably arranged antiferromagnetically already at RT so there is no contribution of copper spins to the effective magnetic moment of Cu 13 Fe 4 V 10 O 44 in the whole investigated temperature range. The lack of detailed structure of Cu 13 Fe 4 V 10 O 44 compound makes it also impossible to infer its magnetic properties from the electronic structure of constituent magnetic ions [21,[37][38][39]. For example, for many compounds with 3d ions the true value of magnetic moments were theoretically derived provided the spin-orbit coupling was explicitly taken into account [37][38][39].…”

“…Strong spin frustration has been the subject of an extensive research interest, both theoretical and experimental, during the last few years. In this respect the study of magnetic pyrochlore oxides containing 4f and 3d transition ions provided many very important results concerning the interdependence of structural and magnetic parameters [21,22]. At temperature close to 10 K a kink on χ(T) curve is noticeable (see inset in Figs.…”