Case study of bilayered spin- 12 square lattice compound VO(HCOO)2·(H2

Abstract

We present the synthesis and a detail investigation of structural and magnetic properties of polycrystalline [VO(HCOO)2·(H2O)] by means of x-ray diffraction, magnetic susceptibility, highfield magnetization, heat capacity, and electron spin resonance measurements. It crystallizes in a orthorhombic structure with space group P cca. It features distorted VO6 octahedra connected via HCOO linker (formate anions) forming a two-dimensional square lattice network with a bilayered structure. Analysis of magnetic susceptibility, high field magnetization, and heat capacity data in terms of the frustrated square lattice model unambiguously establish quasi-two-dimensional nature of the compound with nearest neighbour interaction J1/kB 11.7 K and next-nearest-neighbour interaction J2/kB 0.02 K. It undergoes a Néel antiferromagnetic ordering at TN 1.1 K. The ratio θCW/TN 10.9 reflects excellent two-dimensionality of the spin-lattice in the compound. A strong in-plane anisotropy is inferred from the linear increase of TN with magnetic field, consistent with the structural data.

Efficient Adiabatic Demagnetization Refrigeration to below 50 mK with Ultrahigh-Vacuum-Compatible Ytterbium Diphosphates AYbP2O7 ( Arjun1, Ranjith2, Jesche3 et al. 2023Phys. Rev. AppliedSelf Cite

“…S1 within the Supplemental Material [43]. Similar procedures have been used previously and have shown to be efficient for estimating C ph in cases where heat-capacity data of nonmagnetic analog compounds are not available [44][45][46][47]. The fit is extrapolated down to low temperatures, and the magnetic specific heat dT .…”

Adiabatic demagnetization refrigeration to millikelvin temperatures with the distorted square lattice magnet NaYbGeO4

“…For estimating the C ph , the zero-field data were fitted by a polynomial function C ph (T ) = aT 3 + bT 5 + cT 7 above 10 K, where a, b, and c are appropriate constants [53]. Similar procedures have been adopted earlier and proven to be efficient in cases where heat capacity data of nonmagnetic analog compounds are unavailable [54][55][56][57]. The fit was extrapolated down to low temperatures, and C m was obtained by subtracting the fitted data from the experimental C p data.…”

Quasi-two-dimensional magnetism in spin- square lattice compound Cu[C6H2(COO)4][H3N-(CH2)2-NH3] · 3H2O

“…Thus, this compound is another example of a quasi-2D non-frustrated system with J 1 /T N > 2.7, similar to the compounds tabulated in ref. [26].…”

“…Some of the recent studies have reported the signature of spin nematic phase in BaCdVO(PO 4 ) 2 [23][24][25]. A few metal-organic compounds based on V 4+ and Cu 2+ have also been studied in light of the 2D spin-1/2 Heisenberg model [26][27][28][29]. A series of Cubased quasi-2D organometallic magnets where Cu 2+ ions are bridged by pyrazine molecules are [Cu(HF 2 )(pyz) 2 ]X (X = BF − 4 , ClO − 4 , PF − 6 , SbF − 6 , and AsF − 6 ) [30] and [Cu(pyz) 2 ]X 2 (X = ClO − 4 and BF − 4 ) [31][32][33].…”