A spin glass perspective on ferroic glasses

Sherrington, David C.

doi:10.1002/pssb.201350391

Cited by 39 publications

(29 citation statements)

References 97 publications

(180 reference statements)

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“…Recently, the present author proposed [8,9] that a conceptual explanation may be found in analogy with a soft-spin variant of a conventional spin glass [10][11][12], with the glassy onset of non-ergodicity without global lattice change the analogue of a spin glass transition and the PNRs manifestations of localized state precursors of macroscopic order [13,14], especially simply for a more recently discovered class of isovalent relaxors, such as Ba(Zr 1−x Ti x )O 3 (BZT) in which the B-site ions are occupied randomly by Ti or Zr ions, both of charge +4. BZT is conceptually clearer than heterovalent PMN in which the +4 Ti-ions of PbTiO 3 are replaced randomly by a mixture of one third Mg +2 and two thirds Nb +5, giving rise also to significant effective random fields relative to the charge distribution of the underlying ABO 3 perovskite template 1 .…”

Section: Introductionmentioning

confidence: 99%

Relaxors, spin, Stoner and cluster glasses

Sherrington

2015

Phase Transitions

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It is argued that the main characteristic features of displacive relaxor ferrolectrics of the form A(B, B ′ )O 3 with isovalent B, B ′ can be explained and understood in terms of a soft-pseudospin analogue of conventional spin glasses as extended to itinerant magnet systems. The emphasis is on conceptual comprehension and on stimulating new perspectives with respect to previous and future studies. Some suggestions are made for further studies both on actual real systems and on test model systems to probe further. The case of heterovalent systems is also considered briefly.

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Section: Introductionmentioning

confidence: 99%

Relaxors, spin, Stoner and cluster glasses

Sherrington

2015

Phase Transitions

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“…The demonstrated new type of spin glass may provide insight into the general mechanisms underlying the formation of ferroic glasses [39]. For the applications of NiO and other ultrathin AF films in spin-charge conversion and magnonic (spin wave-based) structures [3,5,10,14], we expect a transition at T B between two different regimes of spin wave propagation, and a large difference between the spin wave characteristics in the multidomain state of thick AF films and the spin-glass state of thin films.…”

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confidence: 99%

Spin glass transition in a thin-film NiO/permalloy bilayer

Urazhdin

2018

Phys. Rev. B

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We experimentally study magnetization aging in a thin-film NiO/Permalloy bilayer. Aging characteristics are nearly independent of temperature below the exchange bias blocking temperature TB, but rapidly vary above it. The dependence on the magnetic history qualitatively changes across TB. The observed behaviors are consistent with the spin glass transition at TB, with significant implications for magnetism and magnetoelectronic phenomena in antiferromagnet/ferromagnet bilayers.The properties of thin-film antiferromagnets (AFs) interfaced with ferromagnets (Fs) first became the subject of intense research in the context of exchange bias (EB) -unidirectional anisotropy acquired by F when the system is cooled through a certain blocking temperature T B [1,2]. They have recently attracted a renewed attention thanks to the high dynamical magnetization frequencies of AFs, enabling applications in fast interconversion and transmission of spin signals [3], and THz optics [4]. Additionally, vanishing magnetization of AFs can enable enhanced spin-transfer efficiency in electronic manipulation of the magnetic states for ultrahigh-density information storage, avoiding the constraints imposed by the angular momentum conservation and the dipolar fields ubiquitous to ferromagnetic systems [5].A number of novel phenomena have been recently observed or predicted for thin AF films, including antiferromagnetic spin-orbit torques [6][7][8], AF magnetoresistance [9], enhanced interconversion between electron spin current and spin waves [3,10], generation of THz signals [4,11], AF exchange springs [12,13], and topological effects [14][15][16]. While some of these phenomena are expected even for standalone AFs, strong exchange coupling at AF/F interfaces provides one of the most efficient approaches to controlling and analyzing the magnetization states of AFs, with the state of F controlled by the magnetic field or spin current, and characterized by the magnetoelectronic or optical techniques. However, despite intense ongoing research, little is known about the dynamical and even static magnetization states of thin AF films in F/AF bilayers.Here, we present measurements of magnetization aging, observed in a thin NiO film after magnetization reversal of an adjacent ferromagnet. Our main result is the observation of an abrupt transition between two qualitatively different aging regimes, which we identify as a glass transition in AF frustrated by the random exchange interaction at the F/AF interface. The insight provided by our findings may enable the implementation of new functionalities in magnetic nanodevices, facilitated by the controlled transition among the multidomain, spinliquid, and spin-glass states of thin-film magnetic systems.The AF in our study was a polycrystalline 15 nmthick NiO layer deposited by reactive sputtering on an oxidized 6 × 6 mm 2 Si substrate. A 10-nm-thick Ni 80 Fe 20 =Permalloy (Py) ferromagnet and a 3 nmthick capping SiO 2 layer were deposited on top. NiO has played a prominent role in recent studies of mag...

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“…[52][53][54] The presence of polar nano-domains of relaxors has also been reported to originate from Anderson localization. [55][56][57][58] Interested readers may refer to refs.…”

Section: Models Of Ferroic Glasses and A Generic Ferroic Glass Phase mentioning

confidence: 99%

Ferroic glasses

Wang

et al. 2017

npj Comput Mater

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Ferroic glasses (strain glass, relaxor and cluster spin glass) refer to frozen disordered states in ferroic systems; they are conjugate states to the long-range ordered ferroic states-the ferroic crystals. Ferroic glasses exhibit unusual properties that are absent in ferroic crystals, such as slim hysteresis and gradual property changes over a wide temperature range. In addition to ferroic glasses and ferroic crystals, a third ferroic state, a glass-ferroic (i.e., a composite of ferroic glass and ferroic crystal), can be produced by the crystallization transition of ferroic glasses. It can have a superior property not possessed by its two components. These three classes of ferroic materials (ferroic crystal, ferroic glass and glass-ferroic) correspond to three transitions (ferroic phase transition, ferroic glass transition and crystallization transition of ferroic glass, respectively), as demonstrated in a generic temperature vs. defectconcentration phase diagram. Moreover, through constructing a phase field model, the microstructure evolution of three transitions and the phase diagram can be reproduced, which reveals the important role of point defects in the formation of ferroic glass and glass-ferroic. The phase diagram can be used to design various ferroic glasses and glass-ferroics that may exhibit unusual properties. 1 are a generic name for ferromagnets, ferroelectrics, and ferroelastics, as well as very recently reported ferrotoroidics.2 They originate from a disorder-order ferroic phase transition at a critical temperature (T c ) and have a long-range ordering of magnetic moment in ferromagnets, electric dipole in ferroelectrics, or lattice strain in ferroelastics below T c (ref. 1). The ordering or symmetry-breaking leads to degenerate states of equivalent domains with the same free energy but different orientations, and in order to minimize the internal energy ferroics naturally possess a multi-domain configuration. Under the external stimuli (such as magnetic/electric/mechanical field, temperature), they exhibit many technologically important phenomena such as a hysteresis loop (a switching behavior between different domains) and magnetic/electric/mechanical strain coupling, and have a wide range of applications as memory devices, actuators, sensors, transduces, etc.1,3-7 However, because of the first-order nature, 1,3-9 the hysteresis is usually quite large especially in ferroelastics and ferroelectrics, 3-7 leading to energy loss and fatigue issues. Moreover, a normal ferroic transition renders many of the interesting properties of ferroic crystals (e.g., superelasticity) that are achievable only in a narrow temperature window around the transition temperature. In this review, we show other two classes of ferroic materials: ferroic glass and glassferroic. The former has unique properties that overcome these drawbacks in the ferroic crystal, whereas the latter can exhibit some superior property combination of its two components. Furthermore, experimental and simulated results have revealed a generic...

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A spin glass perspective on ferroic glasses

Cited by 39 publications

References 97 publications

Relaxors, spin, Stoner and cluster glasses

Relaxors, spin, Stoner and cluster glasses

Spin glass transition in a thin-film NiO/permalloy bilayer

Ferroic glasses

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