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The temperature dependent magnetism of Fe-doped rare earth orthochromite HoCr1-xFexO3(x = 0, 0.2) was investigated by neutron powder diffraction. It is found that the magnetism of Cr(Fe)3+ can be well understood within mean field theory, while the ordering of Ho3+ was induced by the Cr(Fe)3+ sublattice and can be satisfyingly described by an effective S = 1/2 model. The absences of both the most common GxFz configuration of Cr3+ and the ordering of Ho3+ caused by Ho-Ho interaction evidence a strong Ho3+-Cr3+ interaction which dominates this system. On the other hand, a remarkable magnetoelastic strain was observed accompanying the Cr(Fe)3+ ordering. An analysis based on the equation of state with a Grüneisen approximation was performed and revealed magnetic origin of this strain. [ABSTRACT FROM AUTHOR]

The metal-nonmetal transition in Ce- and Rh-substituted PrRu4P12 was investigated through magnetic susceptibility, x-ray superlattice reflection, and inelastic neutron scattering (INS) measurements. The saturation in the magnetic susceptibility at low temperatures suggests a singlet ground state for Pr sites in both compounds. This finding is in contrast to the staggered order of singlet and triplet ground states found in the ordered phase of PrRu4P12, which leads to a diverging susceptibility. The intensities of x-ray superlattice reflections of both compounds develop below 45 K and decrease rapidly below 10 K with a simultaneous decrease in electrical resistivity. INS experiments reveal that 4f electron states in both compounds change drastically from two distinct crystal field (CF) level schemes corresponding to an order parameter in the multipole ordered phase (10 K

We report a systematic crystal growth and characterization of Ca1−yLayFe1−xNixAs2, the newly discovered 112-type iron-based superconductor. After substituting Fe by a small amount of Ni, bulk superconductivity is successfully obtained in high-quality single crystals sized up to 6 mm. Resistivity measurements indicate common features for transport properties in this 112-type iron pnictide, suggest strong scattering from chemical dopants. Together with the superconducting transition temperature Tc, and the Néel temperature TN determined by the elastic neutron scattering, we sketch a three-dimensional phase diagram in the combination of both Ni and La dopings. [ABSTRACT FROM AUTHOR]

The origin of nematic order remains one of the major debates in iron-based superconductors. In theories based on spin nematicity, one major prediction is that the spin-spin correlation length at (0,π) should decrease with decreasing temperature below the structural transition temperature Ts. Here, we report inelastic neutron scattering studies on the low-energy spin fluctuations in BaFe1.935Ni0.065As2 under uniaxial pressure. Both intensity and spin-spin correlation start to show anisotropic behavior at high temperature, while the reduction of the spin-spin correlation length at (0,π) happens just below Ts, suggesting the strong effect of nematic order on low-energy spin fluctuations. Our results favor the idea that treats the spin degree of freedom as the driving force of the electronic nematic order. [ABSTRACT FROM AUTHOR]