Magnetic Properties Of Superlattices Research Articles

Controlling the electronic and magnetic properties in epitaxial LaMnO3/LaScO3 superlattices

Perovskite superlattices (SLs) have attracted considerable interest owing to their rich and diverse physical properties. In this study, epitaxial LaMnO3/LaScO3 SLs were grown using pulsed laser deposition (PLD) by controlling the number of atomic monolayers. Raman spectroscopy combined with x-ray diffraction reciprocal space maps confirmed that the introduction of LaScO3 suppressed Jahn–Teller distortion in the SLs. Electrical transport measurements revealed a thermally activated single-gap behavior which mainly depended on the thickness of LaMnO3 layers. Magnetic measurements indicated that the magnetic properties of the SLs were related to the proportions of LaMnO3 and LaScO3 layers. These results are beneficial for the further understanding of the electronic and magnetic properties of LaMnO3-based SLs.

Magnetic properties of a tri-layer superlattice: Mean field study and Monte Carlo simulation

Magnetic properties of a superlattice that consists of three square layers with Ising spins σ=1/2, s=1 and q=5/2, are investigated by means of standard Monte Carlo simulations and Mean Field Theory. The Hamiltonian model comprises contributions of intralayer and interlayer exchange interactions and the applied external magnetic field. Effects of the external magnetic field on magnetic behaviors have been thoroughly studied in the presence of thermal excitation. Ground state and thermal phase diagrams are numerically computated by both methods. Ground state phase diagrams of the system exhibit one ferromagnetic phase (1/2, 1, 5/2) and three ferrimagnetic ones: (−1/2, 1, 5/2), (−1/2, −1, 5/2) and (−1/2, 1, −5/2). A number of interesting phase diagrams and phenomena have been found, including hysteresis behaviors.

Phase diagrams and magnetic properties of a superlattice with alternate layers

Abstract The phase diagrams and magnetic properties of an Ising superlattice are investigated by means of Monte Carlo simulation based on Metropolis algorithm. The system is formed by alternate layers of spins S = 1 and σ = 3 / 2 . The effects of the exchange coupling interactions and the crystal field on the phase diagrams and magnetic properties of the system are examined. A number of characteristic behaviors have been found. In particular, tricritical point, critical end point, and isolated critical point may occur in the present system.

First-principles investigations of electronic structure and magnetic properties of superlattice between BaMnO3 and cubic perovskite compound

The electronic structure and magnetic properties of the BaMnO3/(Ba1/3Sr1/3Ca1/3)TiO3 ((BSC)T) and BaMnO3/Ba(Ti1/3Zr1/3Hf1/3)O3 (B(TZH)) superlattices are investigated by the density function theory in this report. The results show that the BaMnO3/(BSC)T exhibits half-metallic properties with a gap width of 0.639eV, while the BaMnO3/B(TZH) shows metallic property. For the BaMnO3/B(TZH) superlattice, there is no interface states at the Fermi level EF. This should heavily suppress the spin flipping and tunneling caused by interface states located at the Fermi level EF of a BaMnO3/B(TZH) interface, allowing the transport of the BaMnO3/B(TZH) superlattice to be improved.

Electronic and magnetic properties of oxygen patterned graphene superlattice

Graphene superlattices formed by adsorbing oxygen lines on graphene are studied using spin-polarized density functional theory calculations. It is found that separating zigzag chains (armchair dimer lines) with one oxygen adsorbate on each periodic segment of the chain (line) are sufficient to divide the graphene sheet into series of graphene nanoribbons. The energy band gap of the graphene with armchair (zigzag) oxidation lines (chains) is modulated with line (chain) separation as the width modulation of the freestanding graphene ribbon. The magnetic properties of superlattices with different oxidized line width for both zigzag and armchair oxidized lines are also investigated. Magnetism is found in oxygen-patterned graphene superlattice with zigzag interface and is enhanced with the increasing width of separating oxidation chains.

Molecular beam epitaxial growth and magnetic properties of Co-Pt superlattices oriented along the [001], [110] and [111] axes of Pt

The magnetic and structural properties of epitaxial Co/Pt superlattices, oriented along the [001], [110] and [111] directions of Pt, are presented. We find that the magnetic properties of the superlattices are reproducible and distinctly different for the different orientations. For structures with 3.2Å Co/16.7Å Pt, the easy axis of magnetization is perpendicular to the film plane for growth along Pt[111] but in the film plane for growth along [001]. The [110] oriented superlattices have intermediate behaviour. X-ray and TEM analysis of the superlattices reveals significant differences in interface quality and defect structure for the different orientations. These effects may play a more important role in the origin of magnetic anisotropy than previously assumed.

Properties of magnetic superlattices with antiferromagnetic interfacial coupling: Magnetization, susceptibility, and compensation points.

Magnetic superlattices composed of ferromagnetic films (Fe and Gd) which couple antiferromagnetically at the interfaces are studied. In a magnetic field a variety of different spin configurations are possible. We show how these phases are reflected in magnetization and susceptibility measurements. In particular, a twisted spin configuration is characterized by a much larger susceptibility than an aligned spin configuration. We show that small changes in the layering pattern can lead to large changes in /ital M/(/ital T/) and static susceptibility. In contrast, changes in the value of the interface exchange parameter cause large changes only in the weak-coupling limit.

Magnetic properties of [100] oriented Cu-Ni superlattices

We have fabricated Cu-Ni superlattices with exclusive [100] modulating orientation by using a dc magnetron sputtering system. The layer thicknesses of both Cu and Ni range from 5 to 125 Å. The high quality of the samples is confirmed by the intense satellite peaks in the x-ray diffraction. The spontaneous magnetization at 5 K, which is found to be inversely proportional to the Ni layer thickness, vanishes at two Ni atomic planes. A very large difference in magnetic surface anisotropy has been found between [100] and [111] textured Cu-Ni superlattices, displaying the important role of modulating orientation on the magnetic properties of superlattice.

Magnetic Superlattices

ABSTRACTMagnetic superlattices serve as model systems for the study of thin film, interfacial, proximity, coupling and superlattice phenomena. Due to these phenomena, the physical properties of magnetic superlattices can be tuned in a reproducible fashion by proper control of the preparation process.Magnetic measurements in conjunction with detailed structural characterization provide a fruitful area of research, especially in understanding basic phenomena in magnetism. We describe here briefly a few experimental examples from our work which illustrate the possibilities magnetic superlattices offer for the study of basic phenomena in magnetism.