S. Giri

Coexistence of superparamagnetic and superspin glass behaviors in Co50Ni50 nanoparticles embedded in the amorphous SiO2 host

We investigate the magnetic properties of the nanoparticles of Co50Ni50 alloy embedded in the amorphous SiO2 host with volume fractions, ϕ=5% and 10%. The static and dynamic aspects of the magnetic properties are investigated by temperature and time dependence of low-field dc magnetization and frequency dependence of ac susceptibilities. The experimental results and analyses suggest that the dilution of the Co50Ni50 nanoparticles belongs to the crossover regime from superparamagnetic to superspin glass states, which are distinguished from the atomic canonical spin glasses.

Giant magnetoresistance and large inverse magnetocaloric effect in Ni2Mn1.36Sn0.64 alloy

The magnetoresistance (MR) behaviour and the magnetocaloric effect (MCE) of the ferromagnetic shape memory alloy of nominal composition Ni2Mn1.36Sn0.64 have been investigated. We observe giant negative MR (~ − 48% at 90 kOe) around the martensitic transition (MT) temperature. The observed MR was found to be irreversible with respect to the applied magnetic field, particularly in the vicinity of MT. The sample exhibits a large but positive magnetocaloric effect (a peak value of 5.1 J kg−1 K−1 for the magnetic field changing from 0 to 20 kOe) around MT. A comparison with the other Ni–Mn-based shape memory alloys indicates that the observed MR scales with the magnitude of the MCE.

Reentrant-spin-glass state in Ni 2 Mn 1.36 Sn 0.64 shape-memory alloy

The ground state properties of the ferromagnetic shape memory alloy of nominal composition Ni2Mn1.36Sn0.64 have been studied by dc magnetization and ac susceptibility measurements. Like few other Ni-Mn based alloys, this sample exhibits exchange bias phenomenon. The observed exchange bias pinning was found to originate right from the temperature where a step-like anomaly is present in the zero-field-cooled magnetization data. The ac susceptibility study indicates the onset of spin glass freezing near this step-like anomaly with clear frequency shift. The sample can be identified as a reentrant spin glass with both ferromagnetic and glassy phases coexisting together at low temperature at least in the field-cooled state. The result provides us an comprehensive view to identify the magnetic character of various Ni-Mn-based shape memory alloys with competing magnetic interactions.

Interparticle interaction and size effect in polymer coated magnetite nanoparticles

The value of the surface anisotropy constant Ks as obtained from equation (5) in the 11th line from the top of page 9098 should be Ks= 0.15 × 10-4 Jm-2.

Metastability and magnetic memory effect in Ni 2 Mn 1.4 Sn 0.6

Magnetostructural instability in the ferromagnetic shape memory alloy of composition

Multifunctionality attributed to the self-doping in polycrystalline La0.9MnO3 : Coexistence of large magnetoresistance and magnetocaloric effect

{\mathrm{Ni}}_{2}{\mathrm{Mn}}_{1.4}{\mathrm{Sn}}_{0.6}

Polaron relaxation and hopping conductivity in LaMn 1 − x Fe x O 3

is investigated by transport and magnetic measurements. Large negative magnetoresistance is observed around the martensitic transition temperature

Incommensurate Magnetic Ordering and Spin-Liquid-Like State in a Triangular Lattice BaVS3. Neutron Diffraction and Scattering Study.

(90\char21{}210\phantom{\rule{0.3em}{0ex}}\mathrm{K})

Unusual glassy states in LaMn0.5Fe0.5O3: Evidence of two distinct dynamical freezing processes

. Both magnetization and magnetoresistance data indicate that upon the application of an external magnetic field at a constant temperature, the sample attains a field-induced arrested state which persists even when the field is withdrawn. We observe an intriguing behavior of the arrested state that it can remember the last highest field it has experienced. The field-induced structural transition plays the key role for the observed anomaly and the observed irreversibility can be accounted for by the Landau-type free energy model for the first-order phase transition.

Polar octahedral rotations, cation displacement and ferroelectricity in multiferroic SmCrO3

We report the multifunctionality near room temperature attributed to the self-doping in polycrystalline La0.9MnO3. The peak in the temperature dependence of magnetoresistance (MR) and change of magnetic entropy (ΔSM) are observed at 254 K with −MR=55% at 50 kOe and −SM=4.9 J/kg K at 20 kOe where the Curie temperature and metal-insulator transition coexist at 254 K associated with a first order transition. The correlation between resistivity and ΔSM is observed in a limited region around TC. Here ΔSM is close to the largest reported values in manganites, suggesting that the material is interesting for multiple applications.