Complex magnetic behavior in Ce5Rh4Sn10doped with La

Journal of Physics D: Applied Physics, 2014

Magnetism is a very fascinating and dynamic field. Especially in the last 30 years it has experienced many major advances in the full range from novel fundamental phenomena to new products. Applications such as hard disk drives and magnetic sensors are part of our daily life, and new applications, such as in non-volatile computer random access memory, are expected to surface shortly. Thus it is timely for describing the current status, and current and future challenges in the form of a Roadmap article. This 2014 Magnetism Roadmap provides a view on several selected, currently very active innovative developments. It consists of 12 sections, each written by an expert in the field and addressing a specific subject, with strong emphasize on future potential. This Roadmap cannot cover the entire field. We have selected several highly relevant areas without attempting to provide a full reviewa future update will have room for more topics. The scope covers mostly nano-magnetic phenomena and applications, where surfaces and interfaces provide additional functionality. New developments in fundamental topics such as interacting nano-elements, novel magnon-based spintronics concepts, spin-orbit torques and spin-caloric phenomena are addressed. New materials, such as organic magnetic materials and permanent magnets are covered. New applications are presented such as nano-magnetic logic, non-local and domain-wall based devices, heat-assisted magnetic recording, magnetic random access memory, and applications in biotechnology.

Journal of Physics D: Applied Physics, 2020

Andreas Berger CICnanoGUNE BRTA Following the success and relevance of the 2014 and 2017 Magnetism Roadmap articles, this 2020 Magnetism Roadmap edition takes yet another timely look at newly relevant and highly active areas in magnetism research. The overall layout of this article is unchanged, given that it has proved the most appropriate way to convey the most relevant aspects of today’s magnetism research in a wide variety of sub-fields to a broad readership. A different group of experts has again been selected for this article, representing both the breadth of new research areas, and the desire to incorporate different voices and viewpoints. The latter is especially relevant for thistype of article, in which one’s field of expertise has to be accommodated on two printed pages only, so that personal selection preferences are naturally rather more visible than in other types of articles. Most importantly, the very relevant advances in the field of magnetism research in recent yea...

Journal of Superconductivity and Novel Magnetism, 2007

We studied the magnetic correlations in polycrystalline La 2 NiO 4+δ with δ = 0.18 using electron spin resonance (ESR), which is a local magnetic probe, and magnetic susceptibility. Significant magnetic changes were observed around 160 K. Such changes can be related to the particular order of charge and spins present in this compound.

Nature, 2007

The heavy rare earth elements crystallize into hexagonally close packed (h.c.p.) structures and share a common outer electronic configuration, differing only in the number of 4f electrons they have 1 . These chemically inert 4f electrons set up localized magnetic moments, which are coupled via an indirect exchange interaction involving the conduction electrons. This leads to the formation of a wide variety of magnetic structures, the periodicities of which are often incommensurate with the underlying crystal lattice 2 . Such incommensurate ordering is associated with a 'webbed' topology 3,4 of the momentum space surface separating the occupied and unoccupied electron states (the Fermi surface). The shape of this surface-and hence the magnetic structure-for the heavy rare earth elements is known to depend on the ratio of the interplanar spacing c and the interatomic, intraplanar spacing a of the h.c.p. lattice 5 . A theoretical understanding of this problem is, however, far from complete. Here, using gadolinium as a prototype for all the heavy rare earth elements, we generate a unified magnetic phase diagram, which unequivocally links the magnetic structures of the heavy rare earths to their lattice parameters. In addition to verifying the importance of the c/a ratio, we find that the atomic unit cell volume plays a separate, distinct role in determining the magnetic properties: we show that the trend from ferromagnetism to incommensurate ordering as atomic number increases is connected to the concomitant decrease in unit cell volume. This volume decrease occurs because of the so-called lanthanide contraction 6 , where the addition of electrons to the poorly shielding 4f orbitals leads to an increase in effective nuclear charge and, correspondingly, a decrease in ionic radii.

2015

The hospitality of all of these institutions is gratefully acknowledged. Finally, we thank our families for their support and forbearance with our mental abstraction during this lengthy enterprise. Copenhagen J.J. January 1991 A.R.M. 7 CRYSTAL-FIELD EXCITATIONS IN THE LIGHT RARE EARTHS 312 7.1 MF-RPA theory of simple model systems 313 7.2 Beyond the MF-RPA Theory 322 CONTENTS xi 7.3 Perturbations of the crystal-field system 334 7.3.1 Magnetoelastic effects and two-ion anisotropy 334 7.3.2 Conduction-electron interactions 342 7.3.3 Coupling to the nuclear spins 349 7.4 Magnetic properties of Praseodymium 352 7.4.1 Induced magnetic ordering 352 7.4.2 The magnetic excitations 361 8 PERSPECTIVES FOR RARE EARTH RESEARCH 370 INDEX 398 1.5 RARE EARTH MAGNETISM 51

Physica B: Condensed Matter, 1993

2024

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American journal of materials science and technology, 2013

A series of nickel−chromium−ferrite NiFe 2−x Cr x O 4 (with x = 1.25) nanoparticles (NPs) with a cubic spinel structure and with size d ranging from 1.6 to 47.7 nm was synthesized by the solution combustion method. A dual structure of all phonon modes revealed in Raman spectra is associated with metal cations of different types present in the spinel lattice sites. Mossbauer spectra of small NPs exhibit superparamagnetic behavior. However, the transition into the paramagnetic state occurs at a temperature that is unusually high for small particles (T N is about 240 K in the d = 4.5 nm NPs). The larger NPs with d > 20 nm do not exhibit superparamagnetic properties up to the Neel temperature. From the magnetic and Mossbauer data, the cation occupation of the tetrahedral (A) and octahedral [B] sites was determined (Fe 0.75 Ni 0.25)[Ni 0.75 Cr 1.25 ]O 4. The saturation magnetization M S in the largest NPs is about (0.98−0.95) μ B , which is more than twice higher the value in bulk ferrite (Fe)[CrNi]O 4. At low temperatures the total magnetic moment of the ferrite coincides with the direction of the B-sublattice moment. In the NPs with d > 20 nm, the compensation of the magnetic moments of A-and B-sublattices was revealed at about T com = 360−365 K. This value significantly exceeds the point T com in bulk ferrites NiFe x Cr 2−x O 4 (about 315 K) with the similar Cr concentration. However, in the smaller NPs NiFe 0.75 Cr 1.25 O 4 with d ≤ 11.7 nm, the compensation effect does not occur. The magnetic anomalies are explained in terms of highly frustrated magnetic ordering in the B sublattice, which appears due to the competition of AFM and FM exchange interactions and results in a canted magnetic structure.