Magnetic structure

About: Magnetic structure is a research topic. Over the lifetime, 10787 publications have been published within this topic receiving 207143 citations.

Ferromagnetism at the interfaces of antiferromagnetic FeRh epilayers

Abstract: The nanoscale magnetic structure of FeRh epilayers has been studied by polarized neutron reflectometry. Epitaxial films with a nominal thickness of 500 A were grown on MgO 001 substrates via molecular-beam epitaxy and capped with 20 A of MgO. The FeRh films show a clear transition from the antiferromagnetic AF state to the ferromagnetic FM state with increasing temperature. Surprisingly the films possess a FM moment even at a temperature 80 K below the AF-FM transition temperature of the film. We have quantified the magnitude and spatial extent of this FM moment, which is confined to within 60‐80 A of the FeRh near the top and bottom interfaces. These interfacial FM layers account for the unusual effects previously observed in films with thickness 100 A. Given the delicate energy balance between the AF and FM ground states we suggest a metastable FM state resides near to the interface within an AF matrix. The length scale over which the FM region resides is consistent with the strained regions of the film.

Search for half-metallic ferrimagnetism in V-based Heusler alloys Mn2VZ (Z = Al, Ga, In, Si, Ge, Sn)

Abstract: Using a state-of-the-art full-potential electronic structure method within the local spin density approximation, we study the electronic and magnetic structure of Mn2V-based full Heusler alloys: Mn2VZ (Z = Al, Ga, In, Si, Ge and Sn). We show that small expansion of the calculated theoretical equilibrium lattice constants restores the half-metallic ferrimagnetism in these compounds. Moreover, a small degree of disorder between the V and Z atoms, although it induces some states within the gap, preserves the Slater–Pauling behaviour of the spin magnetic moments and the alloys keep a high degree of spin polarization at the Fermi level, opening the way for a half-metallic compensated ferrimagnet.

Solar magnetic elements at 0".1 resolution. General appearance and magnetic structure

Abstract: New observations of solar magnetic elements in a remnant active region plage near disk center are presented. The observations were obtained at the recently commissioned Swedish l-m Solar Telescope on La Palma. We examine a single 430.5 nm G-band filtergram that resolves ∼70 km (0.1) structures and find new forms of magnetic structures in this particular region. A cotemporal Call H-line image is used to examine the low-chromosphere of network elements. A cotemporal Fe I 630.25 nm magnetogram that resolves structures as small as 120 km (0.18) FWHM with a flux sensitivity of approximately 130 Mx cm -2 quantifies the magnetic structure of the region. A Ni I 676.8 nm Dopplergram establishes relative velocity patterns associated with the network features with an accuracy of about 300 m s -1 . We find that magnetic flux in this region as seen in both the magnetngram and the G-band image is typically structured into larger, amorphous, ribbons which are not resolved into individual flux tubes. The measured magnetic flux density in the ribbon structures ranges from 300 to 1500 Mx cm -2 , the higher values occurring at localized concentrations embedded within the ribbons. The Dopplergram indicates relative down-flows associated with all magnetic elements with some indication that higher downflows occur adjacent to the peak magnetic flux location. The mean absolute magnetic flux density of the remnant plage network is about 130 Mx cm -2 ; in the lowest flux regions of the field-of-view, the mean absolute flux density is approximately 60 Mx cm -2 . Within these quiet regions we do not find evidence of pervasive kilo-gauss strength magnetic elements as seen in recent high resolution internetwork studies. In general, the observations confirm recent 3-dimensional numerical simulations which show that the magnetic field in high-density regions such as plage is concentrated in complex structures that are not generally composed of discrete magnetic flux tubes.

Magnetic Structure of Fe 4 N

Abstract: The magnetic structure of Fe/sub 4/N was examined in a neutron diffraction study. The results are in agreement with a model proposed by Wiener and Berger on the basis of magnetic measurements on a series of related compounds. Ferromagnetically aligned moments of 3 mu /sub B/ and 2 j mu /sub B/ are found fur the corner and face-center Fe atoms (respectively) in the cubic unit cell. The difference in moments is apparently due to bonding interaction between nitrogen, at the body-center position, and the face-center Fe's. (auth)