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The compounds with the general chemical formula RCrTiO5 (R = rare-earth ions) possess an orthorhombic crystal structure having Pbam space group. However, there are limited works carried out on this group of materials, primarily in bulk to explore their structural and magnetic properties. The exploration of structural and magnetic properties of RCrTiO5 compounds in the nano dimension has not been reported to date. This report focuses on the synthesis of DyCrTiO5 nanoparticles using a simple, time saving and cost-effective sol-gel technique to investigate the role of size on structural as well as magnetic properties. The synthesized sample is calcined at 800 °C for three hours. The crystal structure is confirmed from the Le-Bail profile fitting of the x-ray diffraction (XRD) pattern. The DyCrTiO5 nanoparticles are crystallized in an orthorhombic structure with lattice parameters, a, b, c of 7.321 ± 0.001, 8.644 ± 0.002 and 5.840 ± 0.001 A, respectively. The average particle size is found to be 53 ± 3 nm from transmission electron microscopy (TEM). From the temperature-dependent magnetization measurement, the obtained Neel temperature ( T N ) is 147 ± 2 K. In contrast to the bulk form, DyCrTiO5 nanoparticles do not show spin reorientation (SR) which is observed below 37 K or the magnetic compensation because of the dominating contribution of Dy3+ moment. In addition, the irreversibility in magnetization is suppressed when measured as a function of temperature in the heating and cooling cycle of the measurement with increasing the probing magnetic field. This indicates a feature similar to kinetic arrest. In isothermal magnetization measurements, exchange bias effect is observed because of interaction between the uncompensated spins on the surface of the nanoparticles.

The temperature dependence of magnetic susceptibility, χ(T), of the (Cr84Re16)100−xVx alloy system is reported in this contribution. Anomalies are observed at the Neel temperature (TN), associated with the onset of the antiferromagnetic (AF) spin-density-wave (SDW) state, with these anomalies becoming more pronounced as x increases. The TN values determined from χ(T) measurements are in close agreement with that obtained from the measurement of temperature dependence of electrical resistivity, ρ(T). Prominent broad deep minima are observed in χ(T) upon cooling below 100 K which are followed by low temperature peaks in x = 10.4, 10.9 and 12.4 samples. A second anomaly, not associated with TN, is observed at a temperature TO TN.

NiCr2O4 and CoCr2O4 are two distinct members of the chromite family (ACr2O4) having unique structural and magnetic properties. This paper is a continuation of previous work [Mohanty et al., J. Magn. Magn. Mater. 451(2018)20] and is focused on the modification of ferrimagnetic properties in NiCr2O4 by substituting Co ions at Ni sites. In order to do so (Ni1−xCox)Cr2O4 (x = 0, 0.50, 0.75, 1.00) powder samples were synthesized using chemical co-precipitation techniques. Interest is primarily on (Ni0.5Co0.5)Cr2O4 and (Ni0.25Co0.75)Cr2O4 as characterization results on the end members have been reported. It was determined with in-situ temperature dependent X-ray diffraction measurements that these compositions become fully crystallized cubic spinels with space group Fd 3 - m above 700 °C. All samples were subsequently calcined at 900 °C to ensure phase purity and uniform crystallinity. Transmission electron microscopy showed non-uniform distribution of particle sizes with the majority of the particles having bi-pyramidal structures with flat tops for both samples. A comparative account of different ferrimagnetic Curie temperature, θ f or TC, estimations are presented as determined from measured temperature dependences of the following techniques: Fits of the magnetic susceptibility data indicated a minimum value for the (Ni0.5Co0.5)Cr2O4 sample at 56.1 ± 0.9 K, followed by an increase to 76.8 ± 0.4 K for the (Ni0.25Co0.75)Cr2O4 sample; Neutron diffraction measurements gave values of 80 ± 1 K and 87 ± 1 K; Their paramagnetic Curie points, θ p , were determined to be 73.3 and 84.9 K, respectively. The magnetic frustration index f = ΘCW/TC was found to decrease continuously over the series from 11.9 for NiCr2O4 to 7.1 and 6.5 for x = 0.5 and 0.75 respectively with (Ni0.5Co0.5)Cr2O4 being more frustrated than (Ni0.25Co0.75)Cr2O4. Magnetization as a function of applied magnetic field measured at 3 K demonstrates unusually high coercivity for (Ni0.5Co0.5)Cr2O4, supporting the notion for the higher degree of magnetic frustration in this sample. No exchange bias was observed for M (μ0H) in the (Ni0.25Co0.75)Cr2O4 sample measured at 3 K, but did however show a significant anomaly in its hysteresis loop at this temperature. The anomaly in hysteresis behaviour disappeared when measured at 1.7 K and also at higher temperatures. Frequency dependent ac-susceptibility measurements revealed no shift in the peak position with frequency refuting the existence of spin-glass like behavior in both these samples.

Dimensionality effects on epitaxial and polycrystalline Cr 1− x Ru x alloy thin films and in Cr/Cr–Ru heterostructures are reported. X-ray analysis on Cr 0.9965 Ru 0.0035 epitaxial films indicates an increase in the coherence length in growth directions (1 0 0) and (1 1 0) with increasing thickness ( d ), in the range 20≤ d ≤300 nm. Atomic force microscopy studies on these films shows pronounced vertical growth for d >50 nm, resulting in the formation of columnar structures. The Neel temperatures ( T N ) of the Cr 0.9965 Ru 0.0035 films show anomalous behaviour as a function of d at thickness d ≈50 nm. It is interesting to note that this thickness corresponds to that for which a change in film morphology occurs. Experiments on epitaxial Cr 1− x Ru x thin films, with 0≤ x ≤0.013 and d =50 nm, give T N – x curves that correspond well with that of bulk Cr 1− x Ru x alloys. Studies on Cr/Cr 0.9965 Ru 0.0035 superlattices prepared on MgO(1 0 0), with the Cr layer thickness varied between 10 and 50 nm, keeping the Cr 0.9965 Ru 0.0035 thickness constant at 10 nm, indicate a sharp decrease in T N as the Cr separation layers reaches a thickness of 30 nm; ascribed to spin density wave pinning in the Cr layers for d

The magnetic behaviour of a Cr80−xFe20Mnx alloy system with x=2, 7, 10, 13 and 22 has been investigated in the temperature range 2–400 K through measurements of magnetization, electrical resistivity, magnetoresistivity, specific heat and thermal expansion. The temperature vs. Mn concentration magnetic phase diagram of the system is rich in magnetic behaviour with ferromagnetic (FM), antiferromagnetic (AFM) and paramagnetic phase regions and a spin-glass (SG) region at the lowest temperatures. Phase transition temperatures amongst these different magnetic phases could be identified from well-defined anomalies of magnetic origin that are displayed by graphs of the above-mentioned physical properties as a function of temperature. The time relaxation of the thermoremanent, isothermal remanent and field-cooled magnetizations below and above the SG freezing temperature show unusual aspects. These relaxations do not follow the usual superposition principle that is expected for typical SG materials. Negative giant magetoresistance (GMR) is observed in the alloys at 4 K. The GMR initially increases sharply on increasing the Mn content in the alloy system, followed by a tendency towards a saturation negative value for concentrations of more than about 10 at% Mn. Low-temperature plots of Cp/T vs. T2, where Cp is the specific heat, present anomalous behaviour for alloys with x=2, 10 and 22. For x=2 the plot shows an upturn at the lowest temperatures that changes over to a prominent downturn for x=10 and 22. This behaviour is attributed to Fe concentration fluctuations in the alloys, confirming the theoretical model of Matthews.

Electrical resistivity, thermoelectric power and specific heat measurements are reported for a Cr+2.2 at% Al alloy single crystal, having an Al content close to the triple point on the magnetic phase diagram of the Cr–Al alloy system. A weak resistivity component of spin-density-wave origin, not previously observed in alloys near the triple point concentration, is isolated at low temperatures. Its presence is confirmed by the thermoelectric measurements. The specific heat measurements suggest a maximum in the density of states at the Fermi energy for alloy concentrations close to the triple point, a point that appears to be a particular type of critical point for the Cr–Al alloy system.

Measurements of the electrical resistivity and specific heat of (Cr 86 Ru 14 ) 1− x V x alloys are reported. The Neel temperature of this alloy system is driven to 0 K on doping with a critical V concentration x c = 0.104. The results suggest the existence of a quantum critical point at x c .

Measurements of the elastic constants and nonlinear acoustic properties of a Cr +1.9 at % Fe alloy single crystal are reported. The results indicate anomalous magnetoelastic coupling of the spin-density-wave with the acoustic phonons below and around the Neel temperature.