High Hole Mobility and Nonsaturating Giant Magnetoresistance in the New 2D Metal NaCu<sub>4</sub>Se<sub>4</sub> Synthesized by a Unique Pathway

Chen, Haijie; Rodrigues, J. N. B.; Rettie, Alexander J. E.; Song, Tze‐Bin; Chica, Daniel G.; Su, Xianli; Bao, Jianguo; Chung, Duck Young; Kwok, W. K.; Wagner, Lucas K.; Kanatzidis, Mercouri G.

doi:10.1021/jacs.8b11911

Cited by 18 publications

(29 citation statements)

References 70 publications

(164 reference statements)

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“…The positive small Seebeck coefficient S values and rather high electrical conductivity σ indicate p-type metallic conductivity. Thus, the chemical formula can be recorded as (Cs + )[(Cu + ) 4 (Q 2– ) 2 ](Q – ), which resembles some related compounds, such as NaCu 4 Se 4 , NaCu 6 Se 4 , Na 3 Cu 4 S 4 , and NaCu 4 Se 3 , as shown in Table S5 in the Supporting Information. Furthermore, the X-ray photoelectron spectra (XPS) of Cs 3d, Cu 2p, S 2p, and Se 3d with binding energy regions confirm the presence of each element, especially the mixed valence states of Q – and Q 2– in 1 and 2 , respectively.…”

Section: Resultsmentioning

confidence: 99%

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Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

et al. 2021

J. Am. Chem. Soc.

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Crystalline solids that exhibit inherently low lattice thermal conductivity (κlat) have attracted a great deal of attention because they offer the only independent control for pursuing a high thermoelectric figure of merit (ZT). Herein, we report the successful preparation of CsCu4Q3 (Q = S (compound 1), Se (compound 2)) with the aid of a safe and facile boron–chalcogen method. The single-crystal diffraction data confirm the P4/mmm hierarchical structures built up by the mixed-valence [(Cu+)4(Q2–)2](Q–) double anti-CaF2 layer and the NaCl-type Cs+ sublattice involving multiple bonding interactions. The electron-poor compound CsCu4Q3 features Cu–Q antibonding states around E F that facilitates a high σ value of 3100 S/cm in 2 at 323 K. Significantly, the ultralow κlat value of 2, 0.20 W/m/K at 650 K (70% lower than that of Cu2Se), is mainly driven by the vibrational coupling of the rigid double anti-CaF2 layer and the soft NaCl-type sublattice. The hierarchical structure increases the bond multiplicity, which eventually leads to a large phonon anharmonicity, as evidenced by the effective scattering of the low-lying optical phonons to the heat-carrying acoustic phonons. Consequently, the acoustic phonon frequency in 2 drops sharply from 118 cm–1 (of Cu2Se) to 48 cm–1. In addition, the elastic properties indicate that the hierarchical structure largely inhibits the transverse phonon modes, leading to a sound velocity (1571 m/s) and a Debye temperature (189 K) lower than those of Cu2Se (2320 m/s; 292 K).

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Section: Resultsmentioning

confidence: 99%

“…Still with chemical intuition as an inspiration, complex solids have been investigated as stable TE candidates that offer some effective strategies to govern thermoelectric transport. These examples include CsCu 5 S 3 , α-CsCu 5 Se 3 , NaCu 4 Se 4 , and NaCu 6 Se 4 …”

Section: Introductionmentioning

confidence: 99%

Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

et al. 2021

J. Am. Chem. Soc.

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“…The deduced µ is shown in Fig. S3, which follows a T −3/2 dependence in the high-temperature range, suggesting the acoustic phonon scattering [29,30].…”

Section: Electrical and Magnetic Property Characterizationsmentioning

confidence: 95%

Coexistence of large positive and negative magnetoresistance in Cr2Si2Te6 ferromagnetic semiconductor

Zhou

Bai

et al. 2021

Sci. China Mater.

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Magnetoresistance (MR) phenomenon couples the electron transport with magnetic field, which has been at the forefront of condensed matter physics and materials science. Large-MR behaviors are of particularly importance for magnetic sensor and information memory applications, and their scarcity has aroused intensive research. Moreover, due to the different physical origins, combination of large positive and negative MR (pMR and nMR) in one single compound has rarely been reported. In present work, we achieved a coexistence of large pMR and nMR in Cr 2 Si 2 Te 6 ferromagnetic semiconductor single crystal with different field configurations. Specifically, a large nMR of about −60% was obtained under the in-plane field, while a large pMR higher than 1000% took over in the out-of-plane direction. We attribute this field direction-sensitive dualistic large MR behavior to the competition and cooperation effect from the ferromagnetic interaction, orbital scattering and electronic correlation that coexist in Cr 2 Si 2 Te 6 , which contribute to nMR, pMR, and nMR, respectively, in dominated temperature and field ranges, and show different weights under different field directions. The elucidated multiple MR mechanism in this ferromagnetic semiconductor will shed light on the pursuit of coexistence of large pMR and nMR for field-sensitive device applications.

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“…The data was obtained using a Dynacool Physical Property Measurement System (PPMS, Pt pads (~50 nm thick) were sputtered before 25 m gold wires were attached using Ag paste (DuPont 4929N). [42][43] Relevant dimensions (length, width, and thickness) were measured from an SEM image of the sample.…”

Section: Scanning Electron Microscopy-energy Dispersive X-ray Spectromentioning

confidence: 99%

A Natural 2D Heterostructure [Pb_3.1Sb_0.9S₄][Au_xTe_2–x] with Large Transverse Nonsaturating Negative Magnetoresistance and High Electron Mobility

Chen

Malliakas

et al. 2019

J. Am. Chem. Soc.

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We report the two-dimensional (2D) natural heterostructure [Pb3.1Sb0.9S4][AuxTe2-x] (x = 0.52 − 0.36) which shows anomalous, transverse nonsaturating negative magnetoresistance (MR). For x = 0.52, the material has a commensurately modulated structure with alternating [Pb3.1Sb0.9S4] rocksalt layers and atomically thin [AuxTe2-x] sheets, as determined by single crystal X-ray diffraction using a (3 + 1)-dimensional space group; for other x compositions, the modulated structures are absent and the Au and Te atoms are disordered. The transport properties in this system in low temperature (< 100 K) are dominated by an unusual 2D hopping mechanism, while at room temperature a high carrier mobility of ~1352 cm 2 V-1 s-1 is obtained (x = 0.36). The confined electrons within the [AuxTe2-x] layers are also exposed to inter-layer coupling with the insulating [Pb3.1Sb0.9S4] layers and as a result the properties of the heterostructures emerge not only from the constituent layers, but also the interactions between them. Furthermore, the various Au and Te coordination patterns found in the [AuxTe2-x] sheets as a function of x further contribute to a unique electronic structure that leads to the anomalous non-saturating negative MR with different field dependent behaviors. First-principles calculations indicate that the [AuxTe2-x] sheets are responsible for the unusual electrical transport properties in this 2D system.

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High Hole Mobility and Nonsaturating Giant Magnetoresistance in the New 2D Metal NaCu₄Se₄ Synthesized by a Unique Pathway

Cited by 18 publications

References 70 publications

Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

Coexistence of large positive and negative magnetoresistance in Cr2Si2Te6 ferromagnetic semiconductor

A Natural 2D Heterostructure [Pb_3.1Sb_0.9S₄][Au_xTe_2–x] with Large Transverse Nonsaturating Negative Magnetoresistance and High Electron Mobility

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High Hole Mobility and Nonsaturating Giant Magnetoresistance in the New 2D Metal NaCu4Se4 Synthesized by a Unique Pathway

Cited by 18 publications

References 70 publications

Mixed-Valence CsCu4Se3: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu+)4(Se2–)2](Se–) Double Anti-CaF2 Layer and the Soft Cs+ Sublattice

Mixed-Valence CsCu4Se3: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu+)4(Se2–)2](Se–) Double Anti-CaF2 Layer and the Soft Cs+ Sublattice

Coexistence of large positive and negative magnetoresistance in Cr2Si2Te6 ferromagnetic semiconductor

A Natural 2D Heterostructure [Pb3.1Sb0.9S4][AuxTe2–x] with Large Transverse Nonsaturating Negative Magnetoresistance and High Electron Mobility

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High Hole Mobility and Nonsaturating Giant Magnetoresistance in the New 2D Metal NaCu₄Se₄ Synthesized by a Unique Pathway

Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

Mixed-Valence CsCu₄Se₃: Large Phonon Anharmonicity Driven by the Hierarchy of the Rigid [(Cu⁺)₄(Se^2–)₂](Se^–) Double Anti-CaF₂ Layer and the Soft Cs⁺ Sublattice

A Natural 2D Heterostructure [Pb_3.1Sb_0.9S₄][Au_xTe_2–x] with Large Transverse Nonsaturating Negative Magnetoresistance and High Electron Mobility