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Patterned nanostructures on the order of 200 nm × 200 nm of the itinerant ferromagnet SrRuO3 give rise to superparamagnetic behavior below the Curie temperature (∼150 K) down to a sample-dependent blocking temperature. We monitor the superparamagnetic fluctuations of an individual volume and demonstrate that the field dependence of the time-averaged magnetization is well described by the Langevin equation. On the other hand, the rate of the fluctuations suggests that the volume in which the magnetization fluctuates is smaller by more than an order of magnitude. We suggest that switching via nucleation followed by propagation gives rise to Langevin behavior of the total volume, whereas the switching rate is determined by a much smaller nucleation volume. [ABSTRACT FROM AUTHOR]

We study magnetization reversal of nanostructures of the itinerant ferromagnet SrRuO3 (TC ˜ 150 K). We find that down to 10 K the magnetization reversal is dominated by thermal activation. From 2-10 K, the magnetization reversal becomes independent of temperature, raising the possibility for reversal dominated by macroscopic quantum tunneling (MQT). A 10 K crossover to MQT is consistent with the extremely large anisotropy field (˜7T)of SrRu03. [ABSTRACT FROM AUTHOR]

We have measured the temperature dependence of the extraordinary Hall effect (EHE) in ultrathin films of the itinerant ferromagnet SrRuO3. We find that while the resistivity ρ of the films varies significantly with their thickness, the EHE at low temperatures appears to be determined solely by ρ. We discuss possible implications of this observation. [ABSTRACT FROM AUTHOR]

Ferroelastic 90° a-domain dynamics in epitaxial Pb(Zr0.2Ti0.8)O3 (lead zirconium titanate, PZT) films is investigated using lateral and vertical piezoelectric force microscopies. The PZT film consists of out-of-plane polarized c-domains separated by a cross-hatch network of in-plane polarized a-domains. When an electric field is applied across the PZT film, the a-domains are rearranged on the nanoscale. Depending on the direction of the electric field, this results either in larger or more fragmented c-domains. Both lateral and vertical piezoelectric force signals demonstrate the importance of ferroelastic a-domain movement since their dynamics will determine the final polarization retention time and stability of ferroelectric capacitors. [ABSTRACT FROM AUTHOR]

The Hall effect resistivity ?xy of high-quality films of the itinerant ferromagnet SrRuO3 was measured at low temperatures. SrRuO3 films have large uniaxial magnetocrystalline anisotropy, and in the relevant temperature range the easy axis is 30° degrees from the film normal. We measure changes in ?xy associated with changes in the orientation of the magnetization (M) for the same applied magnetic field B [??xy(B,?M)], and we find that with increasing B, ??xy(B,?M) changes its sign and its magnitude becomes more than an order of magnitude larger than the remanent (spontaneous) anomalous Hall effect. Furthermore, it appears that ?xy cannot be described as a sum of a term that depends on B and a term that depends on M, that is, the ordinary Hall effect and the anomalous Hall effect are effectively intermixed. We address qualitatively a possible link between the observed behavior of ?xy and the predicted existence of Weyl nodes in SrRuO3. [ABSTRACT FROM AUTHOR]

SrRuO3 is an itinerant ferromagnet with a Curie temperature of 150 K and a uniaxial magnetocrystalline anisotropy. Using high-quality epitaxial thin films, we measure at 2 K the anisotropic magnetoresistance and the planar Hall effect as a function of the in-plane current direction and the magnetization orientation. We identify three types of contributions related to (a) the orientation of the magnetization relative to the crystal axes, (b) the direction of the current relative to the crystal axes, and (c) the orientation of the magnetization relative to the current. [ABSTRACT FROM AUTHOR]

SrRuO3 is an itinerant ferromagnet and in its thin film form when grown on miscut SrTiO3 has Tc of ∼150 K and strong uniaxial anisotropy. We measured both the Hall effect and the magnetoresistance (MR) of the films as a function of the angle between the field applied and the normal to the films above Tc. We extracted the extraordinary Hall effect that is proportional to the perpendicular component of the magnetization and thus the MR for each angle of field applied could be correlated with the magnitude and orientation of the magnetization induced. We fit the MR data with a second order magnetization expansion, and it indicated large anisotropic MR in the paramagnetic state. The extremum values of resistivity were not obtained for currents parallel or perpendicular to the magnetization, probably due to crystal symmetry. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We inject a sequence of 1 ms current pulses into uniformly magnetized patterns of the itinerant ferromagnet SrRuO3 until a magnetization reversal is detected. We detect the effective temperature during the pulse and find that the cumulative pulse time t required to induce magnetization reversal depends exponentially on 1/T. In addition, we find that τ also depends exponentially on the current amplitude. These observations indicate current-induced magnetization reversal assisted by thermal fluctuations. [ABSTRACT FROM AUTHOR]

We inject current pulses into uniformly magnetized patterns of thin films of the itinerant ferromagnet SrRuO3, while monitoring the effective temperature of the patterns during the current injection. We gradually increase the amplitude of the pulses until magnetization reversal occurs. We observe magnetization reversal induced by current above a temperature-dependent threshold and show that this effect is not simply due to sample heating or Oersted fields. We discuss the applicability of the current-induced spin-wave instability scenario. [ABSTRACT FROM AUTHOR]

We measure the anomalous Hall effect (AHE) resistivity ρxy in thin films of the itinerant ferromagnet SrRuO3. At low temperatures, the AHE coefficient Rs varies with Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed, and at higher temperatures, Rs reaches a peak and then changes sign just below Tc. We find that for all films studied, Rs scales with resistivity in the entire ferromagnetic phase. We attribute the observed behavior to the contribution of the extrinsic side-jumps mechanism and the intrinsic Karplus-Luttinger (Berry phase) mechanism, including the effect of finite scattering rates. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric Pb0.92La0.08Zr0.4Ti0.6O3 (PLZT) thin films were deposited on SrTiO3-buffered Si(001) substrate by on-axis radio frequency magnetron sputtering. X-ray diffraction analysis revealed epitaxial growth of monocrystalline PLZT films, with an (001) rocking curve full width at half maximum of ∼0.3°. φ-scans showed 45° in-plane orientation of the perovskite unit cell relative to that of silicon. The elemental composition of the thin film heterostructure was examined by Auger sputter depth profiling measurements. The recorded profiles suggest that the SrTiO3 buffer layer serves not only as a template for epitaxial growth, but also as a barrier suppressing Pb–Si interdiffusion between the PLZT layer and the Si substrate. The surface roughness of the PLZT layer was measured at ∼4nm for films with ∼500nm thickness. Wavelength dispersions for the refractive index (n) and the extinction coefficient (k) were obtained from spectroscopic ellipsometry measurements, with n∼ 2.48 at the main communication wavelength λ =1550nm and k <0.001 for λ >650nm. Recorded polarization vs. electric field loops for the PLZT epilayer, with a SrRuO3 electrode layer interposed between PLZT and SrTiO3, showed a remnant polarization P r ≈40µC/cm2 and coercive field E c ≈100kV/cm. These findings suggest that the sputter-deposited PLZT thin films retain the functional properties critical to ferroelectric and electro-optic device applications, also when integrated on a semiconductor substrate. [Copyright &y& Elsevier]

SrRuO3 films have large uniaxial magnetocrystalline anisotropy tilted out of the film plane. When cooled in zero field from above the Curie temperature (~150 K), a magnetic domain structure emerges in the form of 200-nm-wide stripes oriented along the in-plane projection of the magnetic easy axis. We measure the interface resistance of the magnetic domain walls by applying a magnetic field perpendicular to the easy axis in the domain-wall plane and perpendicular to this plane and observe hysteretic behavior. Micromagnetic simulations of the results indicate that, depending on the direction in which the field is applied, the domain-wall type (Bloch or Néel) and chirality can be tuned. [ABSTRACT FROM AUTHOR]