Pressure driven magnetic order in Sr[Formula: see text]Ca[Formula: see text]Co[Formula: see text]P[Formula: see text].

The magnetic phase diagram of Sr[Formula: see text]Ca[Formula: see text]Co[Formula: see text]P[Formula: see text] as a function of hydrostatic pressure and temperature is investigated by means of high pressure muon spin rotation, relaxation and resonance ([Formula: see text]SR). The weak pressure dependence for the [Formula: see text] compounds suggests that the rich phase diagram of Sr[Formula: see text]Ca[Formula: see text]Co[Formula: see text]P[Formula: see text] as a function of x at ambient pressure may not solely be attributed to chemical pressure effects. The [Formula: see text] compound on the other hand reveals a high pressure dependence, where the long range magnetic order is fully suppressed at [Formula: see text] kbar, which seem to be a first order transition.

Discovery of Amorphous Iron Hydrides via Novel Quiescent Reaction in Aqueous Solution.

Novel amorphous iron hydrides (AIHs) are synthesized for the first time under ambient conditions by employing novel "quiescent reaction", without stirring for mixing solutions, during a conventional aqueous reduction-precipitation process. The kind and morphology of AIHs are dependent on the processing condition, where two types are found, with one form consisting of a tangle of uniform nanowires and the other being granular in nature. Both AIHs undergo transformation to crystalline α-Fe by heat treatment at 600 °C.

Linear Trimer Formation with Antiferromagnetic Ordering in 1-CrSe Originating from Peierls-like Instabilities and Interlayer Se-Se Interactions.

Anomalous successive structural transitions in layered 1-CrSe with an unusual Cr valency were investigated by synchrotron X-ray diffraction. 1-CrSe exhibits dramatic structural changes in in-plane Cr-Cr and interlayer Se-Se distances, which originate from two interactions: (i) in-plane Cr-Cr interactions derived from Peierls-like trimerization instabilities on the orbitally assisted one-dimensional chains and (ii) interlayer Se-Se interactions through p-p hybridization. As a result, 1-CrSe has the unexpected ground state of an antiferromagnetic metal with multiple Cr linear trimers with three-center-two-electron σ bonds.

Transitions from a Kondo-like diamagnetic insulator into a modulated ferromagnetic metal in FeGaGe.

One initial and essential question of magnetism is whether the magnetic properties of a material are governed by localized moments or itinerant electrons. Here, we expose the case for the weakly ferromagnetic system FeGa Ge , wherein these two opposite models are reconciled, such that the magnetic susceptibility is quantitatively explained by taking into account the effects of spin-spin correlation. With the electron doping introduced by Ge substitution, the diamagnetic insulating parent compound FeGa becomes a paramagnetic metal as early as at y=0.

Highly Spin-Frustrated Magnetism in the Topochemically Prepared Triangular Lattice Cluster Magnets Na A (MoO ) Mo O (A=In, Sc).

The physical properties of novel cluster-based triangular lattice antiferromagnets Na A (MoO ) Mo O (A=In, Sc), synthesized through a topochemical Na-intercalation to nonmagnetic Na A (MoO ) Mo O , are reported. The S=1/2 [Mo ] clusters form a regular triangular lattice, which gives the magnetic system a strong geometrical spin frustration effect. Despite the strong antiferromagnetic couplings among [Mo ] clusters, they show no long-range magnetic orderings down to 0.

Magnetic-Nonmagnetic Phase Transition with Interlayer Charge Disproportionation of Nb Trimers in the Cluster Compound NbCl.

We grew large single crystals of the cluster magnet NbCl with a magnetic triangular lattice and investigated its magnetic properties and crystal structure. In NbCl, the [Nb] cluster has a single unpaired spin, making it an S = 1/2 triangular lattice anti-ferromagnet. At low temperatures, NbCl exhibits a magnetic-nonmagnetic phase transition driven by a charge disproportionation, in which the paramagnetic [Nb] clusters transform into alternating layers of nonmagnetic [Nb] and [Nb] clusters.

Competition between the Direct Exchange Interaction and Superexchange Interaction in Layered Compounds LiCrSe2, LiCrTe2, and NaCrTe2 with a Triangular Lattice.

Physical properties of new S = 3/2 triangular-lattice compounds LiCrSe2, LiCrTe2, and NaCrTe2 have been investigated by X-ray diffraction and magnetic measurements. These compounds crystallize in the ordered NiAs-type structure, where alkali metal ions and Cr atoms stack alternately. Despite their isomorphic structures, magnetic properties of these three compounds are different; NaCrTe2 has an A-type spin structure with ferromagnetic layers, LiCrTe2 is likely to exhibit a helical spin structure, and LiCrSe2 shows a first-order-like phase transition from the paramagnetic trigonal phase to the antiferromagnetic monoclinic phase.

Tetramer spin singlet instability in the fluorine-substituted pyrochlore superconducting system Cd2Re2O7-x F x.

We synthesized polycrystalline samples of the fluorine-substituted pyrochlore rhenates Cd2Re2O7-x F x , and investigated their magnetic, transport and structural properties. The transition temperature T s1, where each Re4 tetrahedron in the Re pyrochlore network alternately expands and contracts, decreases with increasing x from 200 K at x  =  0 to 100 K at x  =  0.5.

Strong Coupling Superconductivity in the Vicinity of the Structural Quantum Critical Point in (Ca(x)Sr(1-x))₃Rh₄Sn₁₃.

The family of the superconducting quasiskutterudites (Ca(x)Sr(1-x))(3)Rh(4)Sn(13) features a structural quantum critical point at x(c)=0.9, around which a dome-shaped variation of the superconducting transition temperature T(c) is found. Using specific heat, we probe the normal and the superconducting states of the entire series straddling the quantum critical point.