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Abstract This communication focuses on recently discovered Ln 3 CrGe 3 Be 2 O 14 (Ln = La–Sm) compounds as a new class of low-dimensional magnets. We conducted the first studies of their magnetic properties by means of the magnetic susceptibility, specific heat, and high-resolution optical spectroscopy measurements of the La and Nd representatives. In La 3 CrGe 3 Be 2 O 14 , which contains only one (chromium) magnetic system, the shortest exchange paths are within isolated chromium chains along the c axis. The compound demonstrates one-dimensional magnetic behavior, i.e., an absence of a long-range order, at least down to 0.4 K, and short-range magnetic correlations with the antiferromagnetic exchange integral along the chains estimated as J Cr = 4.0 ± 0.5 K. In Nd 3 CrGe 3 Be 2 O 14 containing two magnetic subsystems, a splitting of the neodymium Kramers doublets at low temperatures indicates magnetic activity due to both short-range correlations and possible magnetic ordering at 2 K. Graphical abstract Image 1 Highlights • Langasite compound La 3 CrGe 3 Be 2 O 14 demonstrates one-dimensional magnetism. • Antiferromagnetic exchange integral along the Cr chains is 4.0 ± 0.5 K. • Splitting of Nd3+ Kramers doublets explains specific heat Schottky anomaly for Nd 3 CrGe 3 Be 2 O 14. • Nd 3 CrGe 3 Be 2 O 14 orders magnetically at 2 K. [ABSTRACT FROM AUTHOR]

This article investigates the magnetic susceptibility, χ(T), of the two-phase (R32 + C2/c) crystal LaCr3(BO3)4 in the temperature range 2–300 K for two orientations of an external magnetic field. It has been established that both structural modifications of lanthanum chromium borate are ordered antiferromagnetically, with each of them having its own Néel temperature (6.5 and 8.5 K). It has been shown that at T > 60 K, the magnetic susceptibility is well described by the Curie–Weiss law with an effective magnetic moment of μeff = 3.86 μB/Cr3+ and a Curie–Weiss temperature of θ = –23 K. Within the Heisenberg spin chain model, taking into account the interchain exchange interaction, the authors have obtained the following exchange-interaction constants: an antiferromagnetic intrachain exchange (J/k = 4.8 K) and a ferromagnetic interchain exchange (J'/k = –0.28 K). [ABSTRACT FROM AUTHOR]

Highlights • High-pressure optical floating-zone Single crystal growth of Li 2 FeSiO 4 is reported. • Sharp transition to antiferromagnetic order at T N = 17.0 (5) K. • Broad maximum at T m = 28 K points to quasi-low-dimensional magnetism. • Magnetostriction anomalies at 4.2 K indicate a phase transition at B = 14.8 T. Abstract A macroscopic single crystal of γ II -Li 2 FeSiO 4 has been grown by means of the high-pressure optical floating-zone technique. Static magnetic susceptibility χ implies that the tetrahedrally-coordinated Fe 2 + ions are in the high-spin, S = 2 , state. While a sharp decrease in χ implies long-range antiferromagnetic order below T N = 17.0 (5) K , the presence of a broad maximum at T m = 28 K suggests quasi-low-dimensional magnetism. Applying magnetic fields along the easy magnetic a -axis yields additional contributions to the susceptibility ∂ M / ∂ B and magnetostriction for B > 7 T , and an anomaly at B ≈ 14.8 T. [ABSTRACT FROM AUTHOR]

• No long-range magnetic order was found in Pr 3 CrGe 3 Be 2 O 14 langasite down to 0.4 K. • Isolated 1D chains of S = 3/2 Cr3+ are situated perpendicular to 2D Kagomé -layers of Pr3+. • Crystal-field splitting of Pr3+ levels explains Schottky anomaly in specific heat. [Display omitted] We present the results of thermodynamic and optical spectroscopy measurements of the Pr 3 CrGe 3 Be 2 O 14 compound - a member of the recently discovered Be-subgroup of the langasite family. Despite the presence of both rare-earth and transition-metal subsystems in Pr 3 CrGe 3 Be 2 O 14 , no long-range magnetic order has been found down to 0.4 K in terms of both magnetization M and specific heat C p. These data are compared with those on Pr 3 AlGe 3 Be 2 O 14. Both compounds evidence the Schottky anomaly at low temperatures, most pronounced in the case of Pr 3 CrGe 3 Be 2 O 14. [ABSTRACT FROM AUTHOR]

Abstract: Crystal structures and magnetic properties of metal telluromolybdates Co1− x Zn x TeMoO6 (x=0.0, 0.1,…,0.9) are reported. All the compounds have an orthorhombic structure with space group P21212 and a charge configuration of M2+Te4+Mo6+O6. In this structure, M ions form a pseudo-two-dimensional lattice in the ab plane. Their magnetic susceptibility measurements have been performed in the temperature range between 1.8 and 300K. The end member CoTeMoO6 shows a magnetic transition at 24.4K. The transition temperature for solid solutions rapidly decreases with increasing x and this transition disappears between x=0.4 and 0.5, which is corresponding to the percolation limit for the square-planer lattice. From the magnetization, specific heat, and powder neutron diffraction measurements, it is found that the magnetic transition observed in the CoTeMoO6 is a canted antiferromagnetic ordering of Co2+ ions. The antiferromagnetic component of the ordered magnetic moment (3.12(3)μ B at 10K) is along the b-axis. In addition, there exists a small ferromagnetic component (0.28(3)μ B) along the a-axis. [Copyright &y& Elsevier]

Abstract: We report structural and magnetic data of a new transition metal oxide containing hexagonal planes of magnetic () ions in a 5-fold trigonal-bipyramidal coordination of oxygen ions. Static magnetic susceptibility and electron spin resonance (ESR) data as well as numerical quantum Monte-Carlo calculations suggest that Cu spins in the layers are strongly antiferromagnetically coupled with K and form a two-dimensional -Heisenberg honeycomb lattice. Owing to the appreciable interlayer coupling the compound orders magnetically at . Remarkably, ESR gives evidence that the orbital ground state of is not the orbital as in copper oxides with the usual octahedral, square-pyramidal or square-planar coordination, but it is the orbital, which is unique for the cuprates. [Copyright &y& Elsevier]

S=1/2 KCuCl3 has a singlet ground state with a finite spin energy gap Δ=31 K to triplet excited states. The bulk magnetic susceptibility vanishes for T≪Δ according to the singlet nature of the ground state. Astonishingly, recent muon spin relaxation (μSR) measurements reveal fluctuating internal fields down to T=5 K, with the onset of a quasi-static regime below T=5 K. The presence of free electronic magnetic moments and their possible freezing at low T contradicts the bulk picture of KCuCl3. By means of polarized neutron scattering and μSR measurements on single crystals of the same batch, the nature of the local spin susceptibility is studied. The claims of a substantial muon influence in KCuCl3 are reinforced. [Copyright &y& Elsevier]

Abstract: We have synthesized Sr2PrO4, an orthorhombic oxide (S.G. Pbam), which presents a 1D-framework of edge sharing [PrO6] octahedra forming chains along the crystallographic c-axis. These chains containing Pr4+ f1 ion are far from each other and only connected through non-magnetic [SrO6] trigonal prisms. Magnetic susceptibility measurements using a SQUID magnetometer in the temperature range from RT down to 1.7K show a net maximum at 3.4K. We performed neutron powder diffraction experiments collecting patterns at temperatures below and above that of the χ maximum and the data do not show any evidence of magnetic order, which is in contradiction with the apparent feature of bulk measurements. This anomalous behaviour could be due to the low-dimensional nature of the magnetic interactions or by a strong reduction of the rare earth magnetic moment due to the crystal field. [Copyright &y& Elsevier]

We present susceptibility measurements on the natural mineral atacamite, Cu 2 Cl(OH) 3 , for the first time along the three crystallographic axes. Further, we have carried out an elastic neutron diffraction experiment which shows that the symmetry of the magnetic ground state of atacamite is described by a propagation vector q =(1/2 0 1/2). [ABSTRACT FROM AUTHOR]