Noriaki Nishiguchi and Masashige Onoda 2002 J. Phys.: Condens. Matter 14 L551 doi:10.1088/0953-8984/14/28/105
Noriaki Nishiguchi and Masashige Onoda1
Show affiliationsThe structural and magnetic properties of the geometrically frustrated spinel system CdV2O4 with V3+ (S = 1), whose lattice constant and oxygen u-parameter differ significantly from those of isomorphous MgV2O4 and ZnV2O4, have been explored by means of x-ray diffraction and through measurements of the magnetization and nuclear magnetic resonance. CdV2O4 undergoes a cubic–tetragonal structural transition with ct/at = 0.990 as well as a magnetic transition with a jump of the susceptibility at Tc1 = 97 K. Another magnetic anomaly appears at Tc2 = 35 K which may be a transition to the antiferromagnetic state. The analysis in terms of the high-temperature series expansion of up to eighth order precisely indicates the nearest-neighbour exchange-coupling constant for the cubic phase to be J = 44 K. In the vanadium spinel with S = 1, the spin-singlet V4-tetramer model with the exchange coupling Jtet inside V4, where Jtet = 2J, is applicable at temperatures above T ≈ Jtet: for CdV2O4 with Jtet ≤Tc1, all of the susceptibility data for the cubic phase are explained using that model, while for MgV2O4 and ZnV2O4 with Jtet ≥Tc1, it is difficult to account for the data for between Jtet and Tc1. In this sense, the present bound state may be regarded as pseudotetramers.
75.30.Cr Saturation moments and magnetic susceptibilities
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
Issue 28 (22 July 2002)
Received 8 May 2002
Published 5 July 2002
Noriaki Nishiguchi and Masashige Onoda 2002 J. Phys.: Condens. Matter 14 L551
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