Morphotropic Phase Boundaries in Ferromagnets:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Tb</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Dy</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>Fe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>Alloys

Bergstrom, Richard; Wuttig, Manfred; Cullen, Jim; Zavalij, Peter Y.; Briber, Robert M.; Dennis, Cindi L.; Garlea, V. Ovidiu; Laver, Mark

doi:10.1103/physrevlett.111.017203

Cited by 64 publications

(37 citation statements)

References 34 publications

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“…Possible examples include Terfenol, which has been reported to have MPB-like boundaries between R and T phases [172]; Fe-xat%Ga, which is known to have nanoregions featuring a low-symmetry distorted structure embedded in an average cubic matrix near a structural phase boundary [173,174]; or magnetic shape memory alloys, which are known to have magnetic tweed [105].…”

Section: How Might the Twin Wall Energy Be Significantly Decreased?mentioning

confidence: 98%

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Viehland

Salje

2014

Advances in Physics

111

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Domain boundaries typically constitute only a minute fraction of the total volume of a crystal. However, a special (but not unusual) situation can occur in which the domain boundary energy becomes very small. Specifically, the domain size is miniaturized to near-atomic scales and the domain boundary density becomes extremely high. In such cases, the properties of the crystal become dominated by a combination of both the domains and the domain boundaries. This phenomenon differs from most ferromagnetic or ferroelectric materials wherein the motion of the domain boundaries dominates the response. As reported herein, novel emergent phenomena that differ from the properties of either the domains or the domain boundaries may be expected. In this article, we focus on one specific state found in ferroic materials -namely, the adaptive ferroic state. This state can be found, for example, in tweed-like structures in morphotropic phase boundary piezoelectric crystals, ferromagnetic shape memory alloys, and pre-martensitic states. In these materials, the properties of the twin boundaries represent the principal contributors to the functionality of a given system. In fact, further investigations of domain boundary-dominated phenomena could result in novel potential for tailoring functional properties for a desired outcome. It should also be noted that new properties can be designed into twin boundaries that are not the properties of the domains. In this paper, adaptive structures and functional twin boundaries are reviewed, and examples of various observed functionalities (e.g. superconductivity, polarity, and ferroelectricity) and corresponding twin boundary structures are provided. In addition, this review confirms that various theoretically predicted, structurally bridging low-symmetry phases do, in fact, exist. Moreover, the values of the lattice constants of the adaptive state are adjustable parameters that are determined by combinations of cubic, rhombohedral/tetragonal phases, and geometrical invariant conditions. Finally, we show that, in such cases, macroscopic properties are controlled by the unique functionality of the twin walls. Looking forward, domain boundary-dominated phenomena offer an important approach for enhancing the properties of the bulk, and to unique local properties where the "twin is the device". We encourage the community to rethink their approaches to materials by design that have treated the structure as homogeneous and to consider the alternative paradigm where the local structure is different from the apparent average symmetry. PACS: 77 Dielectrics piezoelectrics and ferroelectrics; 64 Equations of state, phase equilibria, and phase transitions; 73 Electronic structure and electrical properties of surfaces, interfaces, thin films, and lowdimensional structures

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Section: How Might the Twin Wall Energy Be Significantly Decreased?mentioning

confidence: 98%

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Viehland

Salje

2014

Advances in Physics

111

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“…Figure 1(b) illustrates the schematic temperaturecomposition phase diagram for Tb 1Àx Dy x Fe 2 , where the orange solid line is the determined part by synchrotron diffraction measurements. 7 The Tb 0.3 Dy 0.7 Fe 2 specimen was cut from a h110i oriented rod fabricated in a unidirectional solidification furnace specially designed for the "one-step" process. 22 Grain size of the oriented polycrystals is often several tens of microns, which allows us to get a "single crystal" for TEM observation.…”

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confidence: 99%

“…For the other transition at $258 K, it is also a structural transition from tetragonal into rhombohedral upon heating, as suggested by the in-situ synchrotron XRD measurements on a similar alloy Tb 0.35 Dy 0.65 Fe 2 . 7 The susceptibility peak in Fig. 2(b) is then deemed as the MPB temperature (T MPB ) for Tb 0.3 Dy 0.7 Fe 2 .…”

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confidence: 99%

Local rhombohedral symmetry in Tb0.3Dy0.7Fe2 near the morphotropic phase boundary

Liu

Pan

et al. 2014

Applied Physics Letters

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The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb0.3Dy0.7Fe2, the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10 nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field.

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“…Since we are searching for spectral features which are distinct from the "smooth" background, it is reasonable to assume that the majority of the observational data can be fitted by the background [49,66]. Therefore a so-called "minimum model", as that employed in…”

Section: Phenomenological Backgroundmentioning

confidence: 99%

“…With proper assumptions of the background contribution, the electron and positron data can instead be used to constrain model parameters of DM, in particular, for those models with very distinct spectral features which are obviously missing in the data [49]. In this work, we focus on the specific scenario that DM particles annihilate into intermediate particle pairs which then decay into standard model particles [50,51].…”

Section: Introductionmentioning

confidence: 99%

Constraints on the box-shaped cosmic ray electron feature from dark matter annihilation with the AMS-02 and DAMPE data

Zhang

Liu

et al. 2018

Phys. Rev. D

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Precise measurements of spectra of cosmic ray electrons and positrons can effectively probe the nature of dark matter (DM) particles. In a class of models where DM particles initially annihilate into a pair of intermediate particles which then decay into standard model particles, box-shaped spectra can be generated. Such a kind of spectra are distinct from astrophysical backgrounds, and can probably be regarded as characteristic features of the DM annihilation. In this work, we search for such a feature in the total electron plus positron spectrum measured by AMS-02 and DAMPE. No significant evidence for such a DM annihilation component has been found. The 95% confidence level upper limits of the velocity-weighted annihilation cross section are derived, which range from ∼ 10 −26 cm 3 s −1 for DM mass of 50 GeV to ∼ 10 −23 cm 3 s −1 for DM mass of 10 TeV.

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Morphotropic Phase Boundaries in Ferromagnets:Tb1−xDyxFe2Alloys

Cited by 64 publications

References 34 publications

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Local rhombohedral symmetry in Tb0.3Dy0.7Fe2 near the morphotropic phase boundary

Constraints on the box-shaped cosmic ray electron feature from dark matter annihilation with the AMS-02 and DAMPE data

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