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The [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] sample was prepared by sol-gel method. The crystallographic and magnetic properties of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] have been studied using x-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mossbauer spectroscopy measurements. The crystal structure of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] was found to be orthorhombic (Pnma) structure with lattice constants [a.sub.o] = 5.486 [Angstrom], [b.sub.o] = 7.761 [Angstrom], and [c.sub.o] = 5.510 [Angstrom] at room temperature. The Curie temperature ([T.sub.c]) is determined to be 160 K by zero field coolded (ZFC) magnetization curve under 5 kOe applied field. The maximum value of magnetic entropy changes, [absolute value of [DELTA][S.sub.M]] is 1.25 J/kg x K at 157 K under 13 kOe applied field. Mossbauer spectrum at 4.2 K was fitted with two independent magnetic components of the magnetic hyperfine fields [H.sub.f,1] = 526 kOe and [H.sub.f,2] = 501 kOe. Mossbauer spectra show that the two well-resolved sextets show nearly equal intensities between them without any external fields. This unusual phenomenon provides direct evidence of the two-phase character of the metallic state in the mixed valence state of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] powder. Index Terms--[La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3], magnetic refrigeration, magnetocaloric effect, Mossbauer spectra, sol-gel method.

The temperature dependence of structure and magnetic anisotropy in off-stoichiometry Ni48.8Mn28.6Ga22.6 alloy in the temperature range 80 - 420 K is examined. 2.0 * 10(super 5) J/m(super 3) is the first magnetic anisotropy constant at 283 K and the magnetic anisotropy constant increases to 2.65 * 10(super 5) j/m(super 3) at 130 K.

Magnetic and transport properties of [Zn.sub.1-x][Mn.sub.x]Ge[As.sub.2] semimagnetic semiconductor with the varying the chemical composition are studied. The high field magnetoresistance has displayed the presence of giant magnetoresistance effect with maximum amplitudes around 50% because of the presence of nanosize ferromagnetic grains. .

The magnetooptical Kerr effect is employed to explain the different shapes exhibited by the hysteresis loops of the GaMnAs thin films grown on different substrates. The linear dependence of the magnetooptical effects on the magnetization components is shown to be extremely helpful in determining the impact of the changing magnetic field on the orientation of magnetization in the loops.

A detailed study is conducted to examine the structure-property relationships of the cubic intermetallic phase [Y.sub.4][Mn.sub.1-x][Ga.sub.12-y][Ge.sub.y] (x = 0- 0.26, y = 0- 4.0) isolated from a molten gallium flux reaction. The octahedral Ga network structure represents a rare example of a system where ferromagnetism could be induced by controlling the vacancies of the magnetic centers.

The various effects of Ru doping on the magnetoresistance and the magnetocaloric effects exhibited by the [Bi.sub.0.4][Ca.sub.0.6][Mn.sub.1-x][Ru.sub.x][O.sub.3] (0

Several analyses are conducted to explain the magnetic, as well as the magnetotransport properties observed in the [La.sub.0.2][Pr.sub.0.5][Ca.sub.0.3]Mn[O.sub.3] compounds. The insulator-metal transition taking place in the compounds is also studied.

Chemical vapor deposition method is used for growing boron-incorporated [Mn.sub.5]SiC nanowires, which have displayed magnetic hysteresis loops at room temperature. The magnetic behavior is dependent on the concentration of the boron incorporation, where large magnetoresistance is seen in lightly boron-incorporated nanowire devices and it has decreased with increase in boron content.

The angular distribution of exchange bias and its size dependence are analyzed in MgO magnetic tunnel junctions with IrMn antiferromagnetic pinning layer. Device size is in the mesoscopic range where the finite number of antiferromagnetic grains has determined the statistical properties of exchange bias.

The article discusses a new pulse laser deposition technique, which can be employed for the fabrication of the highly textured manganese zinc ferrite films on glass substrates. The growth of the textured structure is shown to lead to the introduction of stain in these films.

Several studies are conducted to explain the impact of the different carbon nanotubes on the electromagnetic, as well as microwave absorbing properties of the [La.sub.0.7][Sr.sub.0.3][MnO.sub.3[delta]] (LSMO) composites. The permittivity of the complexes is shown to highly increase with the increase in CNT composition.

The planar Hall effect is employed to explain the magnetization reversal processes of the ferromagnetic [Ga.sub.1- x][Mn.sub.x]As films with different Mn concentrations. The asymmetry observed in the reorientation process for the crossing different directions by these films is also analyzed.

Several powder x-ray diffraction studies are conducted to explain the preparation and the large magnetic entropy changes taking place in the nanocrystalline [Pr.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] compounds. The magnetic ordering of the compounds is shown to be of the second order nature.

The various effects of annealing and homogenization on the structure, as well as the magnetic properties of the [Mn.sub.1.1][Fe.sub.0.9][P.sub.0.8][Ge.sub.0.2] compounds are analyzed. Annealing is shown to lead to a significant increase in the Curie temperature and the magnetic entropy changes of the compounds.

The soft x-ray magnetic circular dichroism technique is employed to explain the temperature-dependent electronic structure of the ferromagnetic double perovskite [La.sub.2]MnNi[O.sub.6]. The line shapes of the system are shown to remain constant with the temperature.

A two-phase model is utilized to determine the field angle dependence of the coercive field of [La.sub.0.67][Sr.sub.0.33]Mn[O.sub.3] thin films grown epitaxially on NdGa[O.sub.3] substrates with different crystallographic orientations. The findings for angle dependence of the coercivity could be applied to better understand and possible engineering of the switching behavior of magnetic tunnel junctions.

Pulsed laser deposition technique is used for preparing orthorhombic HoMn[O.sub.3] films epitaxially on Nb-doped SrTi[O.sub.3] (110) single crystal substrates. The frequency dependence of dielectric properties is attributed to the universal dielectric response models and the hopping conductivity and the dipolar effects induced by the charge carriers have helped in understanding the results.

The resistivity, magnetization, and magnetoresistivity of an [Nd.sub.0.43][Sr.sub.0.57]Mn[O.sub.3]/Y[Ba.sub.2][Cu.sub.3][O.sub.7] (NSMO/YBCO) heterostructure were measured to examine their proximity effects of superconductivity and antiferromagnetism. The evolution of superconducting transition temperature (Tc) and antiferromagnetic transition temperature ([T.sub.N]) with applied current density (J) and magnetic field (H) mark the profound effects of spin injection on destructing the superconductivity as well as the magnetic orders.

The studies of domain structure and magnetization reversal process of exchange-coupled ferromagnet/antiferromagnet bilayers Co(x)/Ir-Mn(10 nm) as a function of both thickness of the Co layer and annealing temperature is presented. The domain size of the structure decreased rapidly for high annealing temperatures, while the results from x-ray diffraction indicated no significant change in the crystallographic texture.

First-principles calculations and experimental measurements were utilized to study the electronic structure and magnetism of an Mn-based Heusler alloy [Mn.sub.2]NiSb. The ferromagnetic coupling observed in [Mn.sub.2]NiSb arise from the larger lattice constant and the Curie temperature of [Mn.sub.2]NiSb of 647 K indicates a strong exchange interaction between Mn atoms.

The quaternary LiMgPdSb-type CoFeMnSi are examined. The analysis of the measured XRD pattern and magnetization curve has shown that the CoFeMnSi compound is crystallized in the structure where half metallicity has occurred.

The electronic structures and magnetic properties of [La.sub.2]MnNi[O.sub.6], a typical ferromagnetic insulator with the double perovskite structure, are examined. The ferromagnetism mechanism is examined in terms of the superexchange interaction and the x-ray absorption spectrum based on the band structure results is calculated.

Anomalous magnetic behavior is found in the polycrystalline Heusler alloy system [Ru.sub.2][Mn.sub.1-x][Fe.sub.x]Ge. The magnetoresistance (MR) effect is described by a model in which antiferromagnetic and ferromagnetic domains are coexisting.

Magnetometry, x-ray, and neutron scattering are used for studying the structural and magnetic properties of a TbMn[O.sub.3] thin film grown on a [001] SrTi[O.sub.3] substrate by pulsed laser deposition. The results have shown that the ferromagnetism is an intrinsic property of the TbMn[O.sub.3] film.

The structural and transport properties of the Bi-substituted [Co.sub.2]Mn[O.sub.4] multiferroic materials are analyzed. The ac conductivity calculated from the dielectric data as a function of temperature and frequency has shown the cross over from small polaron tunneling to correlated barrier hopping type conduction in these materials.

The electronic structure of ferromagnetic double-perovskite [La.sub.2]MnNi[O.sub.6] is examined by using Mn and Ni resonant photoemission spectroscopy (RPES) and soft x-ray absorption spectroscopy (XAS). The Mn and Ni 2p XAS measurements have shown that Mn ions are formally tetravalent and that Ni ions are formally divalent.

The correlation between the exchange bias strength and magnetic domain structure in ferromagnetic (AF) bilayers is clarified by observing ferromagnetic domain structure at Co-[L.sub.3] edge for polycrystalline Mn-Ir/Co-Fe bilyares by using the x-ray magnetic circular dichroism photoelectron emission microscopy method. The studies have shown that the larger size of AF domain, which means small distribution of fixing direction of AF spins, has induced the large exchange bias field.

The magnetorefractive effect in transmission modes (MT-MRE) of epitaxial grown [La.sub.0.7][Pb.sub.0.3]Mn[O.sub.3-[delta]] is measured and analyzed. The crossover of magnetospectroscopic responses from far infrared (FIR) to near IR frequencies is the first evidence of gradual disappearance of the magnetodynamics at higher frequencies, which has resulted from the dynamic Jahn-Teller effect.

A simple nanofabrication process is introduced to tune the exchange bias in the magnetic nanostructures and the InMn/CoFe films are deposited on the porous alumina oxide (AAO) with different pore different diameters. The results have shown that exchange bias is tuned by the AAO pores.

The reorientation of exchange anisotropy in the epitaxial (002) IrMn/CoFe bilayers is examined. The transitions of exchange-bias field from a negative field to a positive field with increasing time scale are observed and the double-shifted magnetization curve in this system is used as an indicator for the relaxation of interfacial spins of IrMn.

The structural and magnetocaloric properties of the perovskite manganite [La.sub.2/3-x][Y.sub.x][Ca.sub.1/3-y][Sr.sub.y]Mn[O.sub.3] are analyzed. The ferromagnetic ordering temperature [T.sub.c] has increased abruptly due to the increase in the competition between A-site size-disorder degree and double-exchange interaction resulting from Mn-O-Mn bond angle and the phase transition is broadened due to the cation disordering at A-site.

The superconducting quantum interference device (SQUID) magnetization measurements are performed on single crystal manganites [La.sub.1-x][Sr.sub.x]Mn[O.sub.3]. The observed anomaly, which is reproduced in the temperature dependence of the NMR frequency, is attributed to a continual decrease in the exchange interaction within the temperature interval 60 K and the difference between [T.sub.MI] and [T.sub.oo] to an inherent inhomogeneity in Sr concentration.

The correlation between the ion-beam bombardment and the exchange bias magnetism in NiFe/Mn bilayers is analyzed. The dependence of the exchange bias field with increasing ion-beam energies has shown that the Ar ion-beam bombardment process has created uncompensated Mn spins or increase the spin misalignment in ferromagnet (FM)/antiferromagnet (AF) interfaces, depending on the energy used.

The phase stability, nonstoichiometry, point defects, and magnetoresistance (MR) of polycrystalline [Sr.sub.2]FeMn[O.sub.6-[delta]] (SFMO) are analyzed. The variation of structural parameters, magnetization and MR is discussed in relation to oxygen nonstoichiometry [delta] and maximum MR if observed for samples with large [delta].

Magneto-optic measurements are used for studying the polarization of the mobile electrons in [La.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] strained thin films grown epitaxially on single crystalline (001) LaAl[O.sub.3] (LAO) and (001) [La.sub.0.3][Sr.sub.0.7][Al.sub.0.65][Ta.sub.0.35][O.sub.9] substrates. The magnetic circular dichroism (MCD) spectra of both the films have shown a peak at the band gap at around 3 eV and the peak is shifted toward lower energy side with the increase in temperature.

The texture, microstructure and magnetotransport properties of c-axis oriented [La.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] (LSMO) films on MgO-buffered Si[O.sub.2]/Si substrates are studied and compared to epitaxial LSMO/MgO (001) and polycrystalline LSMO/Si[O.sub.2]/Si films. The c-axis oriented LSMO films have displayed large low field magnetoresistance (LFMR) that is attributed to the spin-dependent scattering of transport current at the grain boundaries.

Single-phase epitaxial [La.sub.0.47][Ce.sub.0.20][Ca.sub.0.33]Mn[O.sub.3-[delta]] films on (001) SrTi[O.sub.3] are prepared by pulsed laser deposition and by reducing the oxygen pressure for deposition. The temperature dependence of the electrical resistance (R) of the single-phase films has obeyed the thermally activated behavior, the magnetic transition temperature has increased and R has decreased by annealing.

The exchange bias effects in arrays of Cu/NiFe/IrMn/Cu nanoscale antidot arrays prepared by deep ultraviolet lithography are examined. The enhancement in the exchange bias field is attributed to the physical limitations imposed on the IrMn domain size by the reduced lateral dimensions of the antidots.

The anisotropic magnetoresistance (AMR) of epitaxial thin film and polycrystalline samples of [La.sub.0.65][Ca.sub.0.35]Mn[O.sub.3] is measured. At the temperature below the metal-insulator transition (MIT), the AMR of the polycrystalline samples is larger than that of the epitaxial films, showing that the anisotropy of the spin-polarized tunneling of the charge carriers across grain boundaries in a magnetic filed is responsible for the low temperature behavior.