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Abd-Elmeguid, M. M.; Ni, B.; Khomskii, Daniel I.; Pocha, Regina; Johrendt, Dirk; Wang, X.; Syassen, K.

doi:10.1103/physrevlett.93.126403

Cited by 121 publications

(114 citation statements)

References 17 publications

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“…Consequently, the effective electron correlation strength, given by the ratio between the bandwidth and the on-site Coulomb interactions, can be controlled to reach from the weak to the strong coupling regime. In fact, the bandwidth-controlled insulator-to-metal transitions were observed in GaTa 4 Se 4 and GaNb 4 Se 4 23,29 , implying that both the weakly and strongly interacting limits are accessible in a single compound.…”

Section: Resultsmentioning

confidence: 95%

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Kim

Han

et al. 2014

Nat Commun

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The entanglement of the spin and orbital degrees of freedom through the spin-orbit coupling has been actively studied in condensed matter physics. In several iridium oxide systems, the spin-orbital entangled state, identified by the effective angular momentum j eff , can host novel quantum phases. Here we show that a series of lacunar spinel compounds, GaM 4 X 8 (M ¼ Nb, Mo, Ta and W and X ¼ S, Se and Te), gives rise to a molecular j eff state as a new spin-orbital composite on which the low-energy effective Hamiltonian is based. A wide range of electron correlations is accessible by tuning the bandwidth under external and/or chemical pressure, enabling us to investigate the cooperation between spin-orbit coupling and electron correlations. As illustrative examples, a two-dimensional topological insulating phase and an anisotropic spin Hamiltonian are investigated in the weak and strong coupling regimes, respectively. Our finding can provide an ideal platform for exploring j eff physics and the resulting emergent phenomena.

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Section: Resultsmentioning

confidence: 95%

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Kim

Han

et al. 2014

Nat Commun

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“…A direct consequence of this low gap value is the high sensitivity to external perturbation such as hydrostatic pressure which can induce an insulator to metal transition in the AM 4 X 8 compounds [12,13] . In that respect, the [ 14 ] .…”

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confidence: 99%

Electric‐Field‐Induced Resistive Switching in a Family of Mott Insulators: Towards a New Class of RRAM Memories

Cario¹,

Vaju²,

Corraze³

et al. 2010

Advanced Materials

133

145

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[ # ] these authors contributes equally to this work Keywords: resistive switching, non-volatile memory, Mott insulator, metal-insulator transitionThe fundamental building blocks of modern silicon-based microelectronics, such as double gate transistors in non-volatile Flash memories, are based on the control of electrical resistance by electrostatic charging. Flash memories could soon reach their miniaturization limits mostly because reliably keeping enough electrons in an always smaller cell size will become increasingly difficult [1] . The control of electrical resistance at the nanometer scale therefore requires new concepts, and the ultimate resistance-change device is believed to exploit a purely electronic phase change such as the Mott insulator to insulator transition [ 2 ].Here we show that application of short electric pulses allows to switch back and forth between an initial high-resistance insulating state ("0" state) and a low-resistance "metallic" state ("1" state) in the whole class of Mott Insulator compounds AM 4 X 8 (A = Ga, Ge; M= V, Nb, Ta; X = S, Se). We found that electric fields as low as 2 kV/cm induce an electronic phase change in these compounds from a Mott insulating state to a metallic-like state. Our results suggest that this transition belongs to a new class of resistive switching and might be explained by recent theoretical works predicting that an insulator to metal transition can be achieved by a simple electric field in a Mott Insulator [3,4,5] . This new type of resistive switching has potential to build up a new class of Resistive Random Access Memory (RRAM) with fast writing/erasing times (50 ns to 10 µs) and resistance ratios R/R of the order of 25% at room temperature.

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“…Thus the strongest M-M bonds are expected to occur when the bonding set is completely filled with 12 electrons. This is almost the case in GaMo 4 S 8 with 11 electrons per Mo 4 according to an idealized ionic formula Ga 3+ (Mo 3.25+ ) 4 -(S 2− ) 8 , whereas the cluster MO's of GaV 4 S 8 are filled with seven electrons only as shown in Fig. 2.…”

Section: Introductionmentioning

confidence: 95%

“…Transition metal chalcogenides with the cubic GaMo 4 S 8 -type structure [1,2] have been a matter of increasing interest for years because of their physical properties, among them superconductivity under pressure [3,4], metal-insulator transition [5], 4d-ferromagnetism [6], and various structural and magnetic instabilities at low temperatures [7 -12]. All these phenomena reflect the strong coupling of structural, electronic and magnetic degrees of freedom in this system.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature Crystal Structures and Magnetic Properties of the V₄-Cluster Compounds Ga_1-xGe_xV₄S₈

Bichler

Slavik

Johrendt

2009

Zeitschrift Für Naturforschung B

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Solid solutions Ga 1−x Ge x V 4 S 8 (x = 0− 1) were synthesized by solid-state reactions and characterized by temperature-dependent X-ray powder diffraction and static magnetic susceptibility measurements. The compounds crystallize in the cubic GaMo 4 S 8 -type structure (space group F43m), built up by heterocubane-like [V 4 S 4 ] (5−x)+ cubes and [Ga 1−x Ge x S 4 ] (5−x)− tetrahedra arranged in a NaCllike manner. The successive substitution of Ga 3+ by Ge 4+ increases the electron count in the molecular orbitals (MO's) of the V 4 -cluster gradually from seven to eight. We observe an almost linear increase of the magnetic moments, connected with a transition from ferromagnetic to antiferromagnetic ordering around x ≈ 0.5. Remarkably, low-temperature structural phase transitions as known from the ternary compounds were also detected in the solid solutions. The gallium-rich compounds (0 ≤ x < 0.5) undergo rhombohedral distortions like GaV 4 S 8 (space group R3m), whereas distortions to orthorhombic symmetry (space group Imm2) as known from GeV 4 S 8 occur in the germanium-rich part of the solid solutions (0.5 ≤ x ≤ 1).

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Transition from Mott Insulator to Superconductor inGaNb4Se8and

Cited by 121 publications

References 17 publications

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Electric‐Field‐Induced Resistive Switching in a Family of Mott Insulators: Towards a New Class of RRAM Memories

Low-temperature Crystal Structures and Magnetic Properties of the V₄-Cluster Compounds Ga_1-xGe_xV₄S₈

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Transition from Mott Insulator to Superconductor inGaNb4Se8and

Cited by 121 publications

References 17 publications

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Electric‐Field‐Induced Resistive Switching in a Family of Mott Insulators: Towards a New Class of RRAM Memories

Low-temperature Crystal Structures and Magnetic Properties of the V4-Cluster Compounds Ga1-xGexV4S8

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Low-temperature Crystal Structures and Magnetic Properties of the V₄-Cluster Compounds Ga_1-xGe_xV₄S₈