Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

The pulsed laser deposition is a new technique for the growth of thin films,which has been attended generally by people recently The physical principle, unique characteristics and the proceeding of the study were introduced briefly In addation, the result of the PtSi nanometer thin film based on silicon prepared by the pulsed laser deposition was describedPULS

Pulsed laser deposition of thin films

Controlling magnetism by means of electric fields is a key issue for the future development of low-power spintronics1. Progress has been made in the electrical control of magnetic anisotropy2, domain structure3,4, spin polarization5,6 or critical temperatures7,8. However, the ability to turn on and o robust ferromagnetism at room temperature and above has remained elusive. Here we use ferroelectricity in BaTiO3 crystals to tune the sharp metamagnetic transition temperature of epitaxially grown FeRh films and electrically drive a transition between antiferromagnetic and ferromagnetic order with only a few volts, just above room temperature. The detailed analysis of the data in the light of first-principles calculations indicate that the phenomenon is mediated by both strain and field e ects from the BaTiO3. Our results correspond to a magnetoelectric coupling larger than previous reports by at least one order of magnitude and open new perspectives for the use of ferroelectrics in magnetic storage and spintronics.

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Electric-field control of magnetic order above room temperature

Polyol synthesis of nanoparticles: status and options regarding metals, oxides, chalcogenides, and non-metal elements

We report the observation of contrasting magnetic behavior in cobalt ferrite (CFO) thin films deposited on single crystalline magnesium oxide (MgO) and strontium titanate (STO). Epitaxial films on MgO (100) with a lattice mismatch of 0.35% showed out-of-plane anisotropy whereas the films on STO (100) with a lattice mismatch of 7.4% displayed in-plane anisotropy. Stress anisotropy calculated from angle-dependent x-ray diffraction analysis confirmed that the change in anisotropy originates from the lattice mismatch. An additional low-field switching characteristic is observed in the M-H loops of the CFO films, which became prominent with lowering temperature as also evidenced from the rf transverse susceptibility measurements. The obtained results revealed that the low field switching is associated with the film-substrate interface.

Magnetic anisotropy and field switching in cobalt ferrite thin films deposited by pulsed laser ablation

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/admi.201900291

Caloric Effects in Perovskite Oxides

In this paper, we demonstrate through experiments and analysis that the most probable mechanism for the observed ferromagnetism in 2% Mn-doped ZnO thin films is a combination of intrinsic and carrier-mediated interaction of the magnetic moments. While no impurity-phase contributions were detected, a strong correlation between effective carrier densities and ferromagnetism was established. Magnetism in amorphous films with high defect densities were described by a bound magnetic polaron model whereas that in highly conducting films was consistent with a Ruderman-Kittel-Kasuya-Yosida exchange mechanism.

Evidence for carrier-mediated magnetism in Mn-doped ZnO thin films

Highly textured cobalt ferrite (CFO) thin films were grown on Si (100) substrates using oblique-angle pulsed laser deposition (α-PLD). X-ray diffraction and in-depth strain analysis showed that the obliquely deposited CFO films had both enhanced orientation in the (111) crystal direction as well as tunable compressive strains as a function of the film thicknesses, in contrast to the almost strain-free polycrystalline CFO films grown using normal-incidence PLD under the same conditions. Using in situ optical plume diagnostics the growth parameters in the α-PLD process were optimized to achieve smoother film surfaces with roughness values as low as 1–2 nm as compared to the typical values of 10–12 nm in the normal-incidence PLD grown films. Cross-sectional high resolution transmission electron microscope images revealed nanocolumnar growth of single-crystals of CFO along the (111) crystallographic plane at the film–substrate interface. Magnetic measurements showed larger coercive fields (∼10 times) with sim...

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Realization of ferroelectric (FE) devices based on the polarization effects of Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) has reinforced the investigation of this material in multiple dimensions and length scales. Multi-level hierarchical nanostructure engineering in PZT thin fi lms offer dual advantages of variable length-scale and dimensionality. Here, the growth of hierarchically ordered PZT nanohetero structures (Nhs) from PZT seed-layer deposited on SrTiO 3 :Nb (100) substrates, using a physical/chemical combined methodology involving pulsed laser deposition (PLD) and hydrothermal processes, is reported. Systematic SEM, TEM, and Raman spectroscopy studies reveal mixed heteroand homo-epitaxial growth mechanism. In the fi nal stage, 3D Nh units cross-link and form a dense network-like Nh PZT thin-fi lm. FE polarizations are measured without using any polymer fi ll-layer which otherwise introduces huge dielectric losses and lowers the polarization values for a FE device. In benefi t, well saturated and symmetric FE hysteresis loops are observed with high degree of squareness and a high remnant polarization (54 µC cm −2 at a coercive fi eld of 237 kV cm −1 ). This work provides a pathway towards preparing hierarchical PZT Nhs offering coherent design of high-performance FE capacitors for data storage technologies in future.

Devajyoti Mukherjee

Papers

Magnetic anisotropy and field switching in cobalt ferrite thin films deposited by pulsed laser ablation

Caloric Effects in Perovskite Oxides

Evidence for carrier-mediated magnetism in Mn-doped ZnO thin films

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Hierarchically Ordered Nano‐Heterostructured PZT Thin Films with Enhanced Ferroelectric Properties