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We report the discovery of linear magnetoelectric effect in the well-known green phase compound, Sm 2 BaCuO 5 , which crystallizes in the centrosymmetric orthorhombic (Pnma) structure. Magnetization and specific heat measurements reveal the long-range antiferromagnetic ordering of Cu 2+ and Sm 3+ -ions moments at T N1 = 23 K and T N2 = 5 K, respectively. Applied magnetic field induces dielectric anomaly at T N1 whose magnitude increases with field, which results in significant (1.7%) magnetocapacitance effect. On the other hand, the dielectric anomaly observed in zero-applied magnetic field at T N2 shows a small (0.4%) magnetocapacitance effect. Interestingly, applied magnetic field induces an electric polarization below T N1 and the polarization varies linearly up to the maximum applied field of 9 T with the magnetoelectric coefficient α ~ 4.4 ps/m, demonstrating high magnetoelectric coupling. Below T N2 , the electric polarization decreases from 35 to 29 µC/m 2 at 2 K and 9 T due to ordering of Sm-sublattice. The observed linear magnetoelectricity in Sm 2 BaCuO 5 is explained using symmetry analysis.

Phase pure nanoparticles of NaCe(WO 4 ) 2 green phosphor were synthesized via a template-free solvothermal method using water (NaCeW-a) and ethylene glycol (NaCeWb) as reaction solvents. Rietveld refinements using powder neutron diffraction (NPD) data confirms that both NaCeW-a and NaCeWb crystallize in the Scheelite-like tetragonal I4 1 /a space group. However, local structure analysis using total scattering atomic pair distribution function (PDF) refinements in a shorter 'r' range (1.5 to 10 Å) established the noncentrosymmetric I4̅ space group where Na/CeO 8 polyhedra are slightly distorted, distributed in 2b and 2d sites. The interesting observation of noncentrosymmetry locally in both NaCeW-a and NaCeW-b is supported by optical nonlinear second harmonic generation (SHG) measurements. Closer inspection of the scanning electron micrograms showed a distinct difference in the particle morphology as a function of reaction solvent. Observation of the +3 valence state of the cerium ion in NaCe(WO 4 ) 2 via X-ray photoelectron spectroscopy measurements was further corroborated by magnetic (VSM) measurements. In addition, both the samples emitted bright narrow green emission upon UV excitation with no considerable change in emission intensity with respect to solvent. Hence, the sharp green light emission and SHG properties make the NaCe(WO 4 ) 2 a potential candidate for solid state display and nonlinear optical applications.

Extending our earlier investigation of magnetic properties of Nd2NiMnO6, we show that it exhibits a magnetic transition below ∼6 K to a ferrimagnetic state. This behavior is interpreted as arising from a long-range ordering of Nd moments antiferromagnetically coupled to the ferromagnetic Ni–Mn ordered moments. Due to the richness of its multiple magnetic transitions and the easily influenced magnetic state by the application of an external magnetic field, established in our earlier study, it has a remarkable inverse magneto-caloric effect (IMCE) at low temperatures (T < 50 K) together with a significant conventional magneto-caloric effect (CMCE) at the ferromagnetic ordering temperature (Tc ∼ 200 K). IMCE and CMCE correspond to the antiferromagnetic arrangement of Nd and Ni–Mn sublattices and ferromagnetic ordering of Ni–Mn sublattices, respectively. Nd2NiMnO6 with its second order phase transition follows the universal behavior of ∆SM(T); it also shows a power law dependency on the magnetic field as Δ S M ∝ H η .

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SrTi0.5Mn0.5O3 (STMO) is a chemically disordered perovskite having random distribution of Ti and Mn over 1b site. Striking discrepancies about the structural and magnetic properties of STMO demands detailed analysis which is addressed. To explore the magnetic ground state of STMO, static and dynamic magnetic properties were studied over a broad temperature range (2-300 K). The dc, ac magnetization show a cusp like peak at Tf ~ 14 K, which exhibits field and frequency dependence. The thermoremanent magnetization is characterized by using stretched exponential function and characteristic time suggests the existence of spin clusters. Also the other features observed in magnetic memory effect, muon spin resonance/rotation and neutron powder diffraction confirm the existence of cluster spin glass state in STMO, rather than the long range ordered ground state. Intriguingly, the observed spin relaxation can be attributed to the dilute magnetism due to non-magnetic doping at Mn-site and competing antiferromagnetic and ferromagnetic interactions resulting from the site disorder. I. IntroductionCompeting magnetic interactions added to chemical disorder can hinder long range magnetic ordering and may lead to frozen spin states at low temperatures. The key point of present work is to understand such effect of chemical disorder on magnetic ground state of B-site of double perovskite SrTi0.5Mn0.5O3 (STMO). Meanwhile, another important factor which is found to promote the spin-glass (SG) state in double perovskites is geometrical frustration arising from the tetrahedral topology 1,2,3 of the magnetic ion. Here, the term double perovskite has been specifically used for B-site ordered systems having the general formula A2BB'O6. In these systems, geometrical frustration does not always lead to the short range ordered state but can instead produce some more exotic magnetic ground states including spin-ice, spin-liquid etc. 4,5,6 , in addition to long range order. Intriguingly, for B-site ordered double perovskites having magnetic cation at B'-site,

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