Atomic and electronic structure of domains walls in a polar metal

Stone, Greg; Puggioni, Danilo; Lei, Shiming; Gu, Mingqiang; Wang, Ke; Wang, Yu; Ge, Jiacheng; Lu, Xiaochen; Mao, Zhiqiang; Rondinelli, James M.; Gopalan, Venkatraman

doi:10.1103/physrevb.99.014105

Cited by 21 publications

(7 citation statements)

References 34 publications

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“…At room temperature, doped SrTiO 3 is a degenerate semiconductor (metal) for carrier densities greater than ∼10 20 cm –3 ( kT ∼ E F , where k is the Boltzmann constant, T the temperature, and E F the Fermi level) . The depolarization field is therefore less easily screened by the free carriers compared to a metal, and the situation is quite different from other polar metals, such as discussed in refs − .…”

Section: Discussionmentioning

confidence: 95%

Polar Nanodomains in a Ferroelectric Superconductor

2020

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The mechanisms by which itinerant carriers compete with polar crystal distortions are a key unresolved issue for polar superconductors, which offer new routes to unconventional Cooper pairing. Strained, doped SrTiO 3 films undergo successive ferroelectric and superconducting transitions, making them ideal candidates to elucidate the nature of this competition. Here, we reveal these interactions using scanning transmission electron microscopy studies of the evolution of polar nanodomains as a function of doping. These nanodomains are a precursor to the ferroelectric phase and a measure of long-range Coulomb interactions. With increasing doping, the magnitude of the polar displacements, the nanodomain size, and the Curie temperature are systematically suppressed. In addition, we show that disorder caused by the dopant atoms themselves presents a second contribution to the destabilization of the ferroelectric state. The results provide evidence for two distinct mechanisms that suppress the polar transition with doping in a ferroelectric superconductor.

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Section: Discussionmentioning

confidence: 95%

Polar Nanodomains in a Ferroelectric Superconductor

2020

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“…In principle, itinerant electron screening in a (semi)metal might rule out the necessity of electrostaticallydriven domain formation due to the fundamental incompatibility of polarity and metallicity, but the existence of polar domains, formed by local bonding preferences, is still possible since this mechanism is insensitive to the presence of charge carriers 22 . Some progress has been made in, for example, the polar interlocked ferroelastic domains observed in polar metal Ca3Ru2O7 25,26 and the structural defect-mediated polar domains in metallic GeTe. 27 In this context, exploring the domain structures in polar Weyl semimetal would be particularly important because the Weyl points and Fermi-arc connectivity can be manipulated via domain reorientation or locally modified order parameters at these DWs [28][29][30][31] .…”

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confidence: 99%

Polar and phase domain walls with conducting interfacial states in a Weyl semimetal MoTe2

et al. 2019

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Much of the dramatic growth in research on topological materials has focused on topologically protected surface states. While the domain walls of topological materials such as Weyl semimetals with broken inversion or time-reversal symmetry can provide a hunting ground for exploring topological interfacial states, such investigations have received little attention to date. Here, utilizing in-situ cryogenic transmission electron microscopy combined with first-principles calculations, we discover intriguing domain-wall structures in MoTe2, both between polar variants of the low-temperature(T) Weyl phase, and between this and the high-T higher-order topological phase. We demonstrate how polar domain walls can be manipulated with electron beams and show that phase domain walls tend to form superlattice-like structures along the c axis. Scanning tunneling microscopy indicates a possible signature of a conducting hinge state at phase domain walls. Our results open avenues for investigating topological interfacial states and unveiling multifunctional aspects of domain walls in topological materials.

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“…Although only a few exist, polar metals have recently seen a renaissance in interest after the identifications of the designing rules [34,35] and the interesting properties that they may host [36][37][38][39][40][41][42]. LiOsO3 [43,44], TaAs [37,39,40] and Ca3Ru2O7 [42,[45][46][47][48][49] are three representative polar metals that have garnered recent interest. Of these three, TaAs is not magnetic, and LiOsO3 does not show any evidence of magnetic order [43]; by contrast, Ca3Ru2O7 possesses a range of magnetically ordered phases [46,47], that depend sensitively on temperature, applied magnetic field and field orientations.…”

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confidence: 99%

Comprehensive magnetic phase diagrams of the polar metal Ca3(Ru0.95Fe<

et al. 2019

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Polar metals exist as a rather unique class of materials as they combine two seemingly mutually exclusive properties (polar order and metallicity) in one system. So far only a few polar metals have been unambiguously identified; the magnetic ones are exceptionally rare. Here we investigate a 5% Fe doped polar metal Ca3Ru2O7, via electrical transport, magnetization, microstrain and optical second harmonic generation measurements. We report the full magnetic phase diagrams (in the field-temperature space) for magnetic field H//a and H//b, which exhibit distinct field-dependent magnetizations behavior. In particular for H//a we found a new ferromagnetic incommensurate spin structure, which is absent in the pure Ca3Ru2O7. We propose a microscopic spin model to understand this behavior, highlighting the role of Fe doping in tipping the delicate balance of the underlying exchange interaction energy in this system.

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Atomic and electronic structure of domains walls in a polar metal

Cited by 21 publications

References 34 publications

Polar Nanodomains in a Ferroelectric Superconductor

Polar Nanodomains in a Ferroelectric Superconductor

Polar and phase domain walls with conducting interfacial states in a Weyl semimetal MoTe2

Comprehensive magnetic phase diagrams of the polar metal Ca3(Ru0.95Fe<

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