Magnetic Ordering in Relation to the Room-Temperature Magnetoelectric Effect of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Sr</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Co</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Fe</mml:mi><mml:mn>24</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>41</mml:mn></mml:msub></mml:math>

Soda, Minoru; Ishikura, Takeshi; Nakamura, Hiroyuki; Wakabayashi, Yusuke; Kimura, T.

doi:10.1103/physrevlett.106.087201

Cited by 154 publications

(80 citation statements)

References 17 publications

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“…Ti substitutions at the 12k sites decrease the exchange coupling between spins in the R and S blocks whilst Co substitutions change the magnetic anisotropy from uniaxial to an easy cone of magnetization tilted away from the c-axis. The result is to stabilize a non-collinear conical magnetic structure [2,5] which is of high interest in the field of multiferroics [6]. The ME effect at room temperature in SrFe8Ti2Co2O19 was first reported in bulk [7] and, thereafter, in thin films [8].…”

Section: Introductionmentioning

confidence: 99%

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Beevers

Love

Lazarov

et al. 2018

Applied Physics Letters

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Article:Beevers, J. E., Love, C. J., Lazarov, V. K. orcid.org/0000-0002-4314-6865 et al. The magnetoelectric effect in M-type Ti-Co doped strontium hexaferrite has been studied using a combination of magnetometry and element specific soft X-ray spectroscopies. A large increase (> x30) in the magnetoelectric coefficient is found when Co 2+ enters the trigonal bi-pyramidal site. The 5-fold trigonal bi-pyramidal site has been shown to provide an unusual mechanism for electric polarization based on the displacement of magnetic transition metal (TM) ions. For Co entering this site, an offcentre displacement of the cation may induce a large local electric dipole as well as providing an increased magnetostriction enhancing the magnetoelectric effect. INTRODUCTIONThe control of magnetism using applied electric fields offer the possibility of a new generation of ultralow power, high density storage. In this respect, magnetoelectric (ME) multiferroic materials are intensely studied in order to understand how different symmetry breaking orders exist in the same material and how these orders can be coupled. Among the few room temperature single-phase ME multiferroics reported, hexaferrites show potential for device applications as they exhibit a low field ME effect at room temperature [1]. M-type hexaferrites are arranged in different repeating sequences of basic building blocks; the R and S layers [2]. Fe 3+ cations occupy both octahedral (Oh) and tetrahedral (Td) co-ordinated sites in the S block (Wyckoff positions 2a and 4f1) and octahedral sites (12k and 4f2) in the R block, see online supplementary materials. The Ba ion located at positions 2d strongly distorts the octahedral site located at the 2b positions giving rise to a bi-pyramidal 5 fold co-ordination which induces a large uniaxial magnetic anisotropy parallel to the c-axis [3]. However, Co 2+ and Ti 4+ substitutions for Fe 3+ dramatically alters the magnetic properties [4]. Ti substitutions at the 12k sites decrease the exchange coupling between spins in the R and S blocks whilst Co substitutions change the magnetic anisotropy from uniaxial to an easy cone of magnetization tilted away from the c-axis. The result is to stabilize a non-collinear conical magnetic structure [2,5] which is of high interest in the field of multiferroics [6]. The ME effect at room temperature in SrFe8Ti2Co2O19 was first reported in bulk [7] and, thereafter, in thin films [8]. Co 2+ substitutions in ferrite structures are a well-known source of magnetoelastic coupling due to the large orbital moment of Co 2+ [9]. The linear ME coupling, , which is the change in magnetization with an applied electric field is directly proportional to the magnetoelastic coupling, or magnetostriction, , implying that an increase in  increases  [10]. However, a mechanism such as the piezoelectric effect or electrostriction for coupling the applied electric field into strain is also required. Several mechanisms for magnetically induced ferroelectricity have been proposed in recent years [11] with the sp...

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Section: Introductionmentioning

confidence: 99%

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Beevers

Love

Lazarov

et al. 2018

Applied Physics Letters

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“…From the viewpoint of applications, this E-induced reversal of the ferromagnetic M is the most important effect, yet the hitherto developed multiferroics still suffer from difficulties due to the weakness of the spin-induced P and/or to the leaky loss current under high voltage. Nevertheless, some hexaferrite compounds with above-room-temperature conical spin states show promise towards room-temperature operation 43,44 .…”

Section: Reproduced From Ref 39 Iop (A-c); and Ref 42 Macmillan Pmentioning

confidence: 99%

Emergent functions of quantum materials

2017

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Materials can harbour quantum many-body systems, most typically in the form of strongly correlated electrons in solids, that lead to novel and remarkable functions thanks to emergence-collective behaviours that arise from strong interactions among the elements. These include the Mott transition, high-temperature superconductivity, topological superconductivity, colossal magnetoresistance, giant magnetoelectric e ect, and topological insulators. These phenomena will probably be crucial for developing the next-generation quantum technologies that will meet the urgent technological demands for achieving a sustainable and safe society. Dissipationless electronics using topological currents and quantum spins, energy harvesting such as photovoltaics and thermoelectrics, and secure quantum computing and communication are the three major fields of applications working towards this goal. Here, we review the basic principles and the current status of the emergent phenomena and functions in materials from the viewpoint of strong correlation and topology.E mergence is a concept developed for many-body systems, indicating the properties, phenomena, and functions that never appear in the individual elements but are realized only when a huge number of elements get together 1 . Inside materials, emergent phenomena are often seen due to the interaction of electronic states; with recent developments on electronic states in solids schematically summarized in Fig. 1a. Electrons in solids have several degrees of freedom: charge, spin and orbital, and are characterized by the topological nature determined by the atomic potential on the crystal lattice structure, as schematically shown in Fig. 1b. These five attributes are coupled together and determine the overall responses to stimuli, which appear as materials' electrical, magnetic, optical, thermal, and mechanical properties.These collective electrons demonstrate various macroscopic quantum phenomena, the representative example of which is superconductivity. One of the big challenges in condensed matter physics is to increase the temperature (T c ) at which superconductivity can be observed to above room temperature. However, there are many other macroscopic quantum phenomena that are already observable above room temperature. One is magnetism (by the Bohr-van Leeuwen theorem), and the other is ferroelectricity 2,3 . Remarkably, there are common features of these three macroscopic quantum phenomena: the order parameter, which is of quantum origin, behaves as a classical quantity, and the quantum topology plays a crucial role.The topological nature of the electronic states is the key concept in the most recent developments in understanding quantum materials. The quantum Hall effect, topological insulators, and topological superconductors are all characterized by nontrivial topologies in Hilbert space. The Berry phase, which describes the connection and curvature of the subspace of Hilbert space, plays the central role in the unified principle to describe this topological nature 4 . ...

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“…As they expected, SCZ had a similar helical-spiral magnetic ordered state and a resultant magnetoelectric effect at room temperature, as the Z structure contains the same structural components as the Y ferrite. A recent article has demonstrated that the helical spin effect arises in SCZ through the same process as in the ME Y ferrites: That is, in terms of the magnetic superexchange between two Fe sites crossing the boundary between the L and S layers [95]. The Ba ions are near these two sites, and when Ba is substituted by Sr this changes the Fe-O-Fe bond angle through this boundary, i.e.…”

Section: Z Ferritesmentioning

confidence: 97%

Multiferroic and Magnetoelectric Hexagonal Ferrites

Pullar

2014

Mesoscopic Phenomena in Multifunctional Materials

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The hexagonal ferrites, also known as hexaferrites, have become massively important materials commercially and technologically, accounting for the bulk of the total magnetic materials manufactured globally, and they have a multitude of uses and applications. As well as their use as permanent magnets, common applications are as magnetic recording and data storage materials, and as components in electrical devices, particularly those operating at microwave/GHz frequencies for mobile and wireless communications, electromagnetic wave absorbers for electromagnetic compatibility (EMC), radar absorbing materials (RAM) and stealth technologies. One of the most exciting recent developments has been the discovery of single phase magnetoelectric/multiferroic hexaferrites, IntroductionThe hexagonal ferrites are magnetic iron(III)-based oxides with a hexagonal crystal structure (Fig. 7.1), also known as hexaferrites. They have become massively important materials commercially and technologically, and hexaferrites are used in a multitude of applications, for example permanent magnets, electrical motors and transformers, actuators and sensors, information storage, mobile communications, transport, security, defence and aerospace [1]. M-type hexaferrites account for over 90 % of the total permanent magnetic materials

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Magnetic Ordering in Relation to the Room-Temperature Magnetoelectric Effect ofSr3Co2Fe24O41

Cited by 154 publications

References 17 publications

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Emergent functions of quantum materials

Multiferroic and Magnetoelectric Hexagonal Ferrites

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