Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 6: Niederdimensionale Systeme (incl. Peierls-Übergang, organische Leiter, ...)

TT 6.9: Vortrag

Montag, 8. März 2004, 16:15–16:30, H18

Zn₂VO(PO₄)₂: An unfrustrated, s=1/2 Heisenberg antiferromagnetic square lattice system. — •N.S. Kini, E.E. Kaul, and C. Geibel — Max Planck Institute for Chemical Physics of Solids, Dresden

Antiferromagnetic frustrated square lattices consisiting of s=1/2 Heisenberg spins have been reported to give rise to unusual ground states depending on the magnitude of nearest neighbour (J₁) and next nearest neighbour (J₂) interactions. As a part of a study on new frustrated systems, we have investigated the compound Zn₂VO(PO₄)₂, in which V⁴⁺ (s=1/2) ions are located on a perfect square lattice.
Polycrystalline samples were synthesised by solid state reaction and characterised by magnetic susceptibility and specific heat measurements. This compound has been found to be made up of a nearly perfect, unfrustrated, s=1/2 Heisenberg antiferromagnetic square lattice with J₁≈6.8 K and J₂≈0.1 K. Anomalies in the specific heat and in the suscptibility point to a transition to an antiferromagnetic state at 3.2 K. Results of magnetic susceptibility and specific heat measurements will be discussed in the light of various theoretical models.