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The temperature dependence of the hysteretic processes of Co nanowires, which is squarely ordered in an array prepared by electrodeposition in nanopores of alumina membranes, is studied. The results have shown that the thermal stress has affected the temperature dependence of the major hysteresis loop of the nanowire arrays.

A theory of reversible susceptibility tensor based on magnetization vector dynamics as described by the Landau-Lifshitz equation of motion is presented. It is shown that the reversible transverse susceptibility is the zero frequency limit of the ferromagnetic resonance.

The magnetic properties of the ultrafine cobalt ferrite particles with diameter d~3.3 nm are discussed. The particles show the presence of the spin-glasslike surface layer with a thickness of 1 angstrom, which leads to a (small) loop shift in the FC process.

A Preisach-Neel-type able to represent complex magnetization processes for magnetic nanoparticle systems is discussed. Future study, based on the same indentification scheme, will test the ability of the model to predict the behavior of other nanoparticulate samples with stronger interactions.

Exchange coupling bias between Cr and ferromagnetic (FM) bilayers is discussed. Despite the fact that Cr is an itinerant antiferromagnet with spin density wave ordering, exchange bias has been established in a number of Py/Cr and Co/Cr bilayers.

Cobalt (Co) nanocrystalline thin films consisting of Co nanocrystals (NCs) embedded in an amorphous carbon matrix are directly synthesized at ambient temperature by codeposition of Co and carbon using high vacuum dual electron-beam evaporation. It is seen that the saturation magnetization and coercivity substantially increased after annealing compared to the as-deposited films due to coarsening of Co NCs.

Chromium dioxide thin films grown epitaxially on Ti[O.sub.2] substrates exhibited a strong in-plane uniaxial anisotropy. Field dependence of high frequency ([10.sup.6] Hz) transverse susceptibility ([[chi].sub.T]) measurements were used to probe the magnetic anisotropy and switching in Cr[O.sub.2] films for varying temperature (10 K to 300 K) and different orientations of the applied field with respect to the magnetic easy axis. Singular peaks in [[chi].sub.T] were observed and are associated with the anisotropy and switching fields. The [[chi].sub.T] data at low temperatures reveal an unusual variation of the singular peaks. This can be described by including magnetoelastic contributions resulting from the in-plane tensile strain in the film due to lattice mismatch with the substrate. Index Terms--Magnetic anisotropy, magnetoelastic energy, transverse susceptibility.

Precise mapping of fundamental parameters like the anisotropy and switching fields is essential to understand the influence of the relaxation, interactions and other phenomena that govern the dynamic magnetic properties in magnetic nanostructures. Dynamic transverse susceptibility ([[Chi].sub.T]) experiments provide a very sensitive and unique way to probe these features. Using a sensitive resonant method based on a radio frequency (RF) tunnel-diode oscillator (TDO), we have, for the first time, mapped the complete variation of [[Chi].sub.T] in the H-T plane in several nanoparticle systems covering the superparamagnetic and blocked regimes. The variation is described well using theoretical models taking into account the thermal relaxation and anisotropy field distribution. Index Terms--Magnetic anisotropy, nanoparticle, superparamagnetism, transverse susceptibility.

The temperature (T) and field (H) dependence of the transverse susceptibility (XT) of a magnetic nanoparticle system has been investigated. The temperature dependence is found to exhibit characteristic features that can be related to relaxation behavior in nanoscale magnetic systems. To the best of our knowledge, this is the first time the full temperature and field dependence of the experimentally determined transverse susceptibility is presented for a magnetic nanoparticle system. The experimental data are interpreted using a modified coherent magnetization rotation model based on a two level approach. Index Terms--Nanoparticle, superparamagnetism, transverse susceptibility.

The magneto-impedance (MI) of glass-coated Fe-Ni-Cu microwires was investigated for longitudinal radio-frequency (rf) currents up to a frequency of 200 MHz using an rf lock-in amplifier method. The crossover behavior is ascribed to the skin-depth-limited response primarily governed by the field-dependance of the premeability.

We have studied the structural, magnetic, and electronic transport properties of (Sr0.9Ca0.1)3Ru2O7 using single crystals grown by a floating-zone technique. The structure analysis by Rietveld refinements reveals that the Ca substitution for Sr intensifies the structure distortion; the rotation angle of the RuO6 octahedron increases. This structure change tunes magnetic and transport properties dramatically. The magnetic ground state switches from an itinerant metamagnetic state for Sr3Ru2O7 to a nearly ferromagnetic state for (Sr0.9Ca0.1)3Ru2O7. The Fermi liquid behavior occurs in Sr3Ru2O7, but is suppressed in (Sr0.9Ca0.1)3Ru2O7. These results strongly suggest that lattice, spin, and charge degrees of freedom are strongly coupled in this system. The band width narrowing caused by the structure distortion should be responsible for the enhancement of ferromagnetic correlations and the change of transport properties. [ABSTRACT FROM AUTHOR]

Small CrO[sub 2] particles with mean diameters ranging from 11 to 25 nm have been prepared by ball milling. X-ray diffraction studies show a continuous lattice expansion with increasing milling time. A phase transition to Cr[sub 2]O[sub 3] also occurs with a sudden increase in the amount of Cr[sub 2]O[sub 3] found between 5 and 8 h of milling. The decreases of low-field magnetoresistance with increasing milling time is correlated to the expansion of the lattice parameters of CrO[sub 2], which probably leads to the reduction in its spin polarization. High-field magnetoresistance increases with the milling possibly due to the enhanced mixed valence of the chromium, which supports the double exchange model. [ABSTRACT FROM AUTHOR]

Relativistic fermions in topological quantum materials are characterized by linear energy-momentum dispersion near band crossing points. Under magnetic fields, relativistic fermions acquire Berry phase of π in cyclotron motion, leading to a zeroth Landau level (LL) at the crossing point, a signature unique to relativistic fermions. Here we report the unusual interlayer quantum transport behavior resulting from the zeroth LL mode observed in the time reversal symmetry breaking type II Weyl semimetal YbMnBi2. The interlayer magnetoresistivity and Hall conductivity of this material are found to exhibit surprising angular dependences under high fields, which can be well fitted by a model, which considers the interlayer quantum tunneling transport of the zeroth LL's Weyl fermions. Our results shed light on the unusual role of zeroth LLl mode in transport. [ABSTRACT FROM AUTHOR]

It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene and the large direct band gaps in MoS2 monolayers, arise from quantum confinement. However, the influence of reduced dimensions on electron-phonon (e-ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement is expected to produce a suppression of e-ph interactions in 2D systems with rigid boundary conditions, experimental verification of this has remained elusive. Here, we show that the e-ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3SiTe6 atomic crystals. When the thickness of the Nb3SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e-ph interactions caused by quantum confinement of phonons. [ABSTRACT FROM AUTHOR]