2008/04/30 by R. Nath, Alexander A. Tsirlin, A. A. Tsirlin +6 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Crystal Structures and Properties #Polyoxometalates: Synthesis and Applications #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.024418
published as Phys. Rev. B 78, 024418 (2008) · 14 pages, 13 figures, 3 tables; published version
openalex publication_date 2008/07/18 · arxiv created 2008/07/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present a detailed investigation of the magnetic properties of complex vanadium phosphates M(VO)2(PO4)2 (M=Ca and Sr) by means of magnetization, specific heat, 31P NMR measurements, and band-structure calculations. Experimental data evidence the presence of ferromagnetic and antiferromagnetic interactions in M(VO)2(PO4)2, resulting in a nearly vanishing Curie-Weiss temperature \ensuremathθCW\ensuremath≤1 K that contrasts with the maximum of magnetic susceptibility at 3 K. Specific heat and NMR measurements also reveal weak exchange couplings with the thermodynamic energy scale Jc=10--15 K. Additionally, the reduced maximum of the magnetic specific heat indicates strong frustration of the spin system. Band-structure calculations show that the spin systems of the M(VO)2(PO4)2 compounds are essentially three-dimensional with the frustration caused by competing ferromagnetic and antiferromagnetic interactions. Both calcium and strontium compounds undergo antiferromagnetic long-range ordering at TN=1.5 and 1.9 K, respectively. The spin model reveals an unusual example of controllable frustration in three-dimensional magnetic systems.