Unusual phase transitions in two-dimensional telluride heterostructures

Xu, Weifeng; Ding, Keyuan; Shi, Mengchao; Li, Junhua; Chen, Bin; Xia, Mengjiao; Liu, Jie; Wang, Yaonan; Li, Jixue; Ma, E.; Zhang, Ze; Tian, He; Rao, Feng

doi:10.1016/j.mattod.2022.02.009

Cited by 13 publications

(14 citation statements)

References 53 publications

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“…[27] Further experimental and theoretical investigations, e.g. using in situ atomic-scale structural characterization experiments [71][72][73][74] and molecular dynamics simulations via machine-learned interatomic potentials, [75][76][77][78] are anticipated to provide an in-depth understanding of the crystallization kinetics of amorphous CrGT.…”

Section: Understanding the Spin Glass Behaviormentioning

confidence: 99%

Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy

et al. 2023

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The layered crystal structure of Cr2Ge2Te6 shows ferromagnetic ordering at the two‐dimensional limit, which holds promise for spintronic applications. However, external voltage pulses can trigger amorphization of the material in nanoscale electronic devices, and it is unclear whether the loss of structural ordering leads to a change in magnetic properties. Here, it is demonstrated that Cr2Ge2Te6 preserves the spin‐polarized nature in the amorphous phase, but undergoes a magnetic transition to a spin glass state below 20 K. Quantum‐mechanical computations reveal the microscopic origin of this transition in spin configuration: it is due to strong distortions of the CrTeCr bonds, connecting chromium‐centered octahedra, and to the overall increase in disorder upon amorphization. The tunable magnetic properties of Cr2Ge2Te6 can be exploited for multifunctional, magnetic phase‐change devices that switch between crystalline and amorphous states.

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Section: Understanding the Spin Glass Behaviormentioning

confidence: 99%

Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy

et al. 2023

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“…The bonding mechanism and optical characters in layered chalcogenides could be further explored by evaluating the thickness‐dependent properties in ultrathin films [ 82–86 ] or in the alternately grown heterostructure thin films, such as the TiTe 2 /Sb 2 Te 3 heterostructure. [ 87–90 ] At last, we note that presence of the inverse block defects should also affect the electronic and thermal conduction like other extended defects, such as swapped bilayers [ 91 ] and stacking faults with non‐QL blocks, [ 92 ] which could be tailored for thermoelectric [ 93,94 ] and topological [ 92,95 ] applications of trigonal Sb 2 Te 3 and related chalcogenides.…”

Section: Discussionmentioning

confidence: 99%

Metavalent Bonding in Layered Phase‐Change Memory Materials

Zhang

Sun

et al. 2023

Advanced Science

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Metavalent bonding (MVB) is characterized by the competition between electron delocalization as in metallic bonding and electron localization as in covalent or ionic bonding, serving as an essential ingredient in phase‐change materials for advanced memory applications. The crystalline phase‐change materials exhibits MVB, which stems from the highly aligned p orbitals and results in large dielectric constants. Breaking the alignment of these chemical bonds leads to a drastic reduction in dielectric constants. In this work, it is clarified how MVB develops across the so‐called van der Waals‐like gaps in layered Sb2Te3 and Ge–Sb–Te alloys, where coupling of p orbitals is significantly reduced. A type of extended defect involving such gaps in thin films of trigonal Sb2Te3 is identified by atomic imaging experiments and ab initio simulations. It is shown that this defect has an impact on the structural and optical properties, which is consistent with the presence of non‐negligible electron sharing in the gaps. Furthermore, the degree of MVB across the gaps is tailored by applying uniaxial strain, which results in a large variation of dielectric function and reflectivity in the trigonal phase. At last, design strategies are provided for applications utilizing the trigonal phase.

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“…Due to this, it exhibits metalloid type properties and demonstrates nonideal formation and crystallization abilities. It has a strong tendency toward anisotropic growth, and this distinctive property of tellurium has been widely explored by several researchers to synthesize nanostructures with different shapes, sizes, and morphologies to tailor-make their properties. ,− Since the structures, properties, and reactivities of metal–telluride semiconductors frequently differ from their lighter metal chalcogenide analogues of sulfur and selenium, they are often called mavericks among the chalcogens . Additionally, metal–tellurides have a shorter bandgap and absorb light at longer wavelength; hence, their applications in solar-energy-harvesting devices is gradually gaining momentum.…”

Section: Introductionmentioning

confidence: 99%

Maneuvering Tellurium Chemistry to Design Metal–Telluride Heterostructures for Diverse Applications

2022

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Heterostructures of metal chalcogenides have attracted immense attention due to their enhanced charge transport, synergistic optoelectronic and catalytic properties. While heterostructures of metal−sulfide or metal−selenide nanocrystals have been studied extensively, those of metal−telluride nanocrystals are less explored due to the lower abundance of tellurium. However, tellurium, a group VI element placed at the border between metals and nonmetals in the periodic table, has the ability to adopt multiple oxidation states, from positive to negative, and a strong proclivity toward anisotropic growth. These singularizes it from other chalcogenide semiconductors and also helps the design of nanostructures of tellurium using Te(0) and Te 2− as the initial precursors. Hence, understanding Te chemistry for nanostructure formation in solution is an essential research area that needs further exploration. Considering this, herein, the synthesis of metal−telluride heterostructures using various chemical routes has been elaborated. The chemistry of the formation of these materials using the direct-seeded approach, cation and anion exchange, and coupling with noble metals, among other methods, are detailed in this review. Furthermore, different device applications of the Te-based heterostructures are analyzed and their performances are summarized. Additionally, the chemical manipulation of tellurium chemistry to engineer complex nanoheterostructures and their possible applications are also proposed as future prospects.

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Unusual phase transitions in two-dimensional telluride heterostructures

Cited by 13 publications

References 53 publications

Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy

Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy

Metavalent Bonding in Layered Phase‐Change Memory Materials

Maneuvering Tellurium Chemistry to Design Metal–Telluride Heterostructures for Diverse Applications

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Unusual phase transitions in two-dimensional telluride heterostructures

Cited by 13 publications

References 53 publications

Spin Glass Behavior in Amorphous Cr2Ge2Te6 Phase‐Change Alloy

Spin Glass Behavior in Amorphous Cr2Ge2Te6 Phase‐Change Alloy

Metavalent Bonding in Layered Phase‐Change Memory Materials

Maneuvering Tellurium Chemistry to Design Metal–Telluride Heterostructures for Diverse Applications

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Product

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Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy

Spin Glass Behavior in Amorphous Cr₂Ge₂Te₆ Phase‐Change Alloy