Singlet Ground State of the Quantum Antiferromagnet Ba3CuSb2O9

We present local probe results on the honeycomb lattice antiferromagnet Ba3CuSb2O9. Muon spin relaxation measurements in zero field down to 20 mK show unequivocally that there is a total absence of spin freezing in the ground state. Sb NMR measurements allow us to track the intrinsic susceptibility of the lattice, which shows a maximum at around 55 K and drops to zero in the low-temperature limit. The spin-lattice relaxation rate shows two characteristic energy scales, including a field-dependent crossover to exponential low-temperature behavior, implying gapped magnetic excitations.Comment: Accepted for publication in Physical Review Letter

Bis(1-ethyl-3-methylimidazolium) 3,6-diselanylidene-1,2,4,5-tetraselena-3,6-diphosphacyclohexane-3,6-diselenolate

In the title compound, 2C6H11N2+·P2Se82− or [EMIM]2P2Se8 (EMIM = 1-ethyl-3-methylimidazolium), the anions, located about inversion centers between EMIM cations, exhibit a cyclohexane-like chair conformation. The cations are found in columns along the a axis, with centroid–centroid distances of 3.8399 (3) and 4.7530 (2) Å. The observed P—Se distances and Se—P—Se angles agree with other salts of this anion

Structural, morphological and electrical properties of Cu2ZnSn1-xSixS4 (x = 0.8, x = 1) for solar-cells applications

International audienc

Substitution of Li for Cu in Cu 2 ZnSnS 4 : Toward Wide Band Gap Absorbers with Low Cation Disorder for Thin Film Solar Cells

International audienc

Synthesis, structural determination and magnetic properties of layered hybrid organic-inorganic, iron (II) propylphosphonate, Fe[(CH3(CH2)(2)PO3)(H2O)], and iron (II) octadecylphosphonate, Fe[(CH3(CH2)(17)PO3)(H2O)]

International audienceFe[(CH3(CH2)2PO3)(H2O)] (1) and Fe[(CH3(CH2)17PO3)(H2O)] (2) were synthesized by reaction of FeCl2·6H2O and the relevant phosphonic acid in water in presence of urea and under inert atmosphere. The compounds were characterized by elemental and thermogravimetric analyses, UV visible and IR spectroscopy. The crystal structure of (1) was determined from X-ray single crystal diffraction studies at room temperature: monoclinic symmetry, space group P21, a=5.707(1)Å, b=4.811(1)Å, c=11.818(2)Å, and β=98.62(3)°. The compound is lamellar and the structure is hybrid, made of alternating inorganic and organic layers along the c direction. The inorganic layers consist of Fe(II) ions octahedrally coordinated by five phosphonate oxygen atoms and one from the water molecule, separated by bi-layers of propyl groups. A preliminary structure characterization of compound (2) suggests a similar layered structure, but with an interlayer spacing of 40.3 Å. The magnetic properties of the compounds were both studied by a dc and ac SQUID magnetometer. Fe[(CH3(CH2)2PO3)(H2O)] (1) obeys the Curie Weiss law at temperatures above 50 K (C=3.81cmKmol, θ=-62K), indicating a Fe +II oxidation state, a high-spin d6 (S=2) electronic configuration and an antiferromagnetic exchange couplings between the near-neighbouring Fe(II) ions. Below T=22K, Fe[(CH3(CH2)2PO3)(H2O)] exhibits a weak ferromagnetism. The critical temperature of T=22K has been determined by ac magnetic susceptibility measurements. Compound (2) shows the same paramagnetic behaviour of the iron (II) propyl derivative. The values of C and θ were found to be 3.8cmKmol and ‑44 K, respectively, thus suggesting the presence of Fe +II ion in the S=2 spin state and antiferromagnetic interactions between Fe(II) ions at low temperatures. Zero-field and field cooled magnetic susceptibility vs. T plots do not overlap below T=30K, suggesting the presence of an ordered magnetic state. The critical temperature, T, has been located by the peaks at T=26K from the ac susceptibility (χ′and χ″) vs. T plots. Below T hysteresis loops recorded in the temperature region 1

Effect of the chemical composition of co-sputtered Zn(O,S) buffer layers on Cu(In,Ga)Se 2 solar cell performance

International audienc

Electrical properties of Cu 2 Zn(Sn 1−x Si x )S 4 ( x = 0.1, x = 0.4) compounds for absorber materials in solar-cells

International audienc

Chemical crystallographic investigation on Cu2S-In2S3-Ga2S3 ternary system

International audienc

Gapless quantum spin liquid ground state in the spin-1 antiferromagnet 6HB- Ba 3 NiSb 2 O 9

International audienc